Workshop Handbook Project Presenstations and Poster Abstracts … version.pdf · Co-Director Stanford Photonics Research Centre W. M. Keck Foundation Professor of Electrical Engineering,

11th Annual CUDOS Workshop

2012

31 January - 3 February

Shoal Bay Resort and Spa

Shoal Bay, NSW, Australia

Project Presentations & Poster Abstracts

Contents

1 Plenary Session

5 Hybrid Integration

9 Nanoplasmonics

14 Terabit per Second

22 Mid-Infrared Photonics

26 Quantum Integrated Photonics

35 Functional Metamaterials

41 Student Posters

88 Staff Posters

136 Selected Presenter Profiles

1

PLENARY SESSION, Tuesday, 31 January

SESSION SCHEDULE

Benjamin Eggleton

Director CUDOS

Director’s Introduction

David A. B. Miller

Co-Director Stanford Photonics Research

Centre

W. M. Keck Foundation Professor of Electrical

Engineering, Stanford

Joining Optics and Electronics – Why

and How?

Ortwin Hess

Leverhulme Chair in Metamaterials,

Department of Physics and Co-Director,

Centre for Plasmonics & Metamaterials,

Imperial College London

Extreme Control of Light in

Metamaterials: From ‘Trapped

Rainbows’ to Nanoplasmonics Meta-

Lasers.

Shanhui Fan

Associate Professor of Electrical Engineering,

Stanford

Non-reciprocity without magneto-optics

2


Joining Optics and Electronics – Why and How?

David A. B. Miller

Ginzton Lab, Stanford University, Nano Building, 348 Via Pueblo Mall, Stanford CA 94305-4088,

USA, [email protected]

http://www-ee.stanford.edu/~dabm/

Interconnect power and density have become dominant constraints in information processing at all levels from

the chip to the data center, and will continue to be for the foreseeable future and beyond. This talk will

summarize the requirements on optics and optoelectronics if they are to solve these problems, and discuss

specific topics from novel device approaches using germanium quantum wells and nanophotonic and

nanometallic structures to fundamental limits to the optical components we may have to make.

mailto:[email protected]

http://www-ee.stanford.edu/~dabm/

3


Extreme Control of Light in Metamaterials:

From ‘Trapped Rainbows’ to Nanoplasmonic Meta-Lasers.

Ortwin Hess

The Blackett Laboratory, Department of Physics

Imperial College London, London SW7 2AZ, United Kingdom

[email protected]

Metamaterials and ‘slow light’ have during the last ten years evolved to two of the most exciting realms of

photonics, enabling a wealth of exciting and useful applications such as sub-diffraction-limited lenses,

‘invisibility’ cloaks and ‘trapped rainbow’ storage and stopping of broadband light.

In the first part the talk will give an overview of recent advances in slow and stopped light in nano-plasmonic

metamaterials and waveguides, explaining how and why by the ‘trapped rainbow’ effect [1] these structures

can enable controlled stopping of light even in the presence of disorder and losses [2]. Exploiting extreme

nonlinear optics in nano-gap waveguides we will demonstrate the existence of nanometer-sized optical solitons

with femtosecond duration [3].

The talk will then establish the microscopic theory of amplification and lasing in nanoplasmonic metamaterials,

demonstrate the possibility of loss-compensation [4] and amplification [5] on the meta-molecular level and

elucidate the nonlinear spatio-temporal dynamics of nanoplasmonic metamaterial lasers [6].

REFERENCES

[1] K L Tsakmakidis, A D Boardman and O Hess, Nature 450, 397 (2007).

[2] E Kirby, J M Hamm, T W Pickering, K L Tsakmakidis and O Hess, Phys Rev B 84, 041103(R) (2011).

[3] A Pusch, J M Hamm, and O Hess, Phys Rev A 84, 023827 (2011).

[4] S Wuestner, A Pusch, K L Tsakmakidis. J M Hamm and O Hess, Phys Rev Lett 105, 127401 (2010).

[5] J M Hamm, S Wuestner, K L Tsakmakidis and O Hess, Phys Rev Lett 107, 167405 (2011).

[6] S Wuestner, J M Hamm, A Pusch, F Renn, K L Tsakmakidis and O Hess (submitted, 2011).

4


Non-reciprocity without magneto-optics

Shanhui Fan1,2,* , Zongfu Yu1, Kejie Fang¹, and Victor Liu¹

¹Ginzton Laboratory, Stanford University, Stanford, CA 94305

²Centre for Ultrahigh bandwidth Devices for Optical Systems, University of Sydney,

Australia

*Phone: 1-650-724-4759

*Email: [email protected]

To achieve on-chip non-reciprocal devices, such as optical isolators, without using magneto-optical materials, one cannot

use any system containing only static dielectric materials described by symmetric dielectric tensors, including such system

that has gain or loss. Here, we show that dynamic modulation provides an effective mechanism to reproduce the effect of

magneto-optical isolators without the use of magneto-optics.

Optical isolators, which suppress back reflection, are of essential importance for constructing large-scale optical

networks. Traditional optical isolators use magneto-optical materials that are difficult to integrate on-chip. As a

result, there is substantial recent interest in developing non-magnetic isolators.

To understand the design of optical isolators, it is very important to reiterate some of the basic theoretical

constraints. Based on the reciprocity theorem [1], any system that is described by static and symmetric dialectric

tensors cannot function as an isolator, since such a system always possesses a symmetric scattering matrix. This

theorem precludes most nanophotonic structures, including some of those that were recently proposed in the

literature [2], for use as isolators [3].

Here we show theoretically and computationally that a properly designed dynamic modulation can break

reciprocity, and accomplish all functionalities of magneto-optical effects [4]. This prediction has been recently

demonstrated experimentally [5]. We further show that dynamic modulation can introduce an effective gauge

potential for photons, achieving an optical analogue of the Aharonov-Bohm effect [6].

References [1] H. A. Haus, Waves and Fields in Optoelectronics, (Prentice-Hall, 1984).

[2] L. Feng et al., “Nonreciprocal light propagation in a silicon photnoic circuit”, Science 333, 729 (2011).

[3] S. Fan et al., “Comment on ‘Nonreciprocal light propagation in a silicon photnoic circuit’ by Feng et al”, Science (in press).

[4] Z. Yu and S. Fan, “Complete optical isolation created by indirect interband photonic transitions”, Nature Photonics 3, 91

(2011).

[5] H. Lira, Z. Yu, S. Fan and M. Lipson, “Electrically driven optical isolator” (submitted).

[6] K. Fang, Z. Yu and S. Fan, “Photonic Aharonov-Bohm effect based on dynamic modulation” (submitted).


5

HYBRID INTEGRATION, Wednesday, 1 February

SESSION SCHEDULE

Science Leader

Barry Luther Davies

Professor, Laser Physics Centre, ANU

Overarching Project Goals

Project Leader

Arnan Mitchell

Professor, School of Electrical and Computer

Engineering, RMIT

2011 Project Milestone Achievements

Steve Madden

Senior Fellow, Laser Physics Centre, ANU

Hybrid integration to reduce total chip

insertion losses

Thach Nguyen

Senior Research Fellow, School of Electrical

and Computer Engineering, RMIT

Silicon Photonic Platforms for Hybrid

Integration

Hendrik Steigerwald

Postdoctoral Fellow, School of Electrical and

Computer Engineering, RMIT

Direct write domain engineering of

Ti:LiNb03 waveguides

Arnan Mitchell

2012 Project Milestones

Discussion

Invited Speaker

Gunther Roelkens

Professor, Photonics Research Group,

University of Ghent

Heterogeneous III-V/silicon photonic

integrated circuits for communications

and sensing

6


Hybrid integration to reduce total chip insertion losses

Steve Madden

Centre for Ultrahigh bandwidth Devices for Optical Systems

Laser Physics Centre, ANU, Canberra

Phone: +61-2-6125-8574

Email: [email protected]


7


Silicon Platforms for Hybrid Integration

Giang Thach Nguyen


School of Electrical and Computer Engineering, RMIT University

Phone: +61-3-9925 2029


A selection of research into thin, shallow-ridge silicon-on-insulator waveguides operating in TM polarization

with controlled lateral leakage into the TE mode is presented. Methods for utilising this strong, coherent lateral

leakage behaviour to realise new photonic devices including sensors and nonlinear optic elements are explored.

Opportunities for the use of the highly evanescent TM mode in hybrid integration with slots and also gain

media are also discussed.

Direct write domain engineering of To:LiNbO3 waveguides

Hendrik Steigerwald



Phone: +61-3-9925 2090


Scanning focused, strongly absorbed UV light across the +z face of LiNbO3 inhibits poling, while on all other

faces domains are directly written by the UV light. The underlying mechanisms are based on lithium

redistribution and thermoelectric fields, respectively. These methods are used for domain engineering in Ti

indiffused LiNbO3 waveguides to develop a platform for integrated non-linear optics.

8


Heterogeneous III-V/silicon photonic integrated circuits for communications and sensing

Gunther Roelkens

University of Ghent (INTEC)

Phone: +32-9-264 3593


Silicon-based photonic integrated circuits are gaining considerable importance for a variety of applications, from

telecommunications to sensors. The interest in this technology stems mostly from the expectation that the

maturity and low cost of CMOS-technology can be applied for advanced photonics products. Other driving

forces for silicon photonics include the design richness associated with high refractive index contrast as well as

the potential for integration of photonics with electronics. Building laser sources and other opto-electronic

devices on integrated silicon circuits is a long sought goal, on one hand in order to complete the functionality of

the integrated circuit but on the other hand also as a manufacturing approach for opto-electronic devices on

large wafers in CMOS-fabs. In terms of device performance the most successful approach to date is definitely the

hybrid (also called heterogeneous) III-V on silicon laser. In this device thin layers of III-V semiconductors are

bonded to silicon. The laser cavity gets its gain from the III-V layers but couples its output light into a silicon

waveguide. Often part of the cavity structure is implemented by means of patterning in silicon, thereby taking

advantage of the resolution and accuracy of lithography tools in CMOS fabs. In that sense these hybrid III-

V/silicon lasers take the best of two worlds.

In this presentation we will outline different types of integrated laser sources on a silicon platform, with a focus

on emission at 1.3um and 1.55um. Besides communications, we will also elaborate on our first steps in the field

of photonic integration for the short-wave and mid-infrared, for sensing applications.

Fig. 1: Example of the heterogeneous integration of InGaAsSb detectors on an SOI waveguide circuit for photodetection in

the 2-2.5um wavelength range

9

NANOPLASMONICS, Wednesday, 1 February

SESSION SCHEDULE

Science Leader

Min Gu

Professor and Director, Centre for Micro-

Photonics, Swinburne University of Technology


Project Leader

Michael Ventura

Postdoctoral Fellow, Centre for Micro-


2011 Project milestone achievements &

2012 goals

Gerd Schröder-Turk

Postdoctoral Researcher, Friedrich-Alexander

Universität Erlangen-Nürnberg, Germany

Minimal surfaces and nets as chiral

photonic materials

Yaoyu Cao

Postdoctoral Fellow, Centre for Micro-


Super-resolution photoinduction-

inhibited nanofabrication based on the

two-photon absorption process

Isabelle Staude

Postdoctoral Fellow, College of Physical and

Mathematical Sciences, ANU

Nanoantennas for efficient broadband

unidirectional emission enhancement

Chris Poulton

Senior Lecturer, School of Mathematical

Sciences, University of Technology, Sydney

Modal methods and Impedance for

nanoplasmonic structures and

metamaterials

Discussion

10


Minimal surfaces and nets as chiral photonic materials

G. E. Schröder-Turk1, M. Saba1, M. D. Turner3, A.-L. Robisch1, K. Mecke1, M. Thiel2 & M. Gu3

1 Theoretische Physik, University Erlangen, 91058 Erlangen, Germany 2 Center for Functional Nanostructures, Karlsruhe Institute of Technology, Karlsruhe, Germany

3 Centre for Micro-Photonics & CUDOS, Swinburne University of Technology, VIC 3122, Australia

Phone: +49 175 9265792


We have recently demonstrated that the chiral nanostructure realised by nature in the wing-scales of several

butterfly species is a dielectric photonic crystal with strong circular dichroism [1,2]. We have also demonstrated

the use of the underlying chiral structure, called Gyroid minimal surface or srs net, for custom-designed photonic

materials [1-3]. While the srs net has attracted much recent attention, many further triply-periodic chiral

networks and surfaces are known whose optical properties remain largely unexplored. Here we draw attention

to two chiral triply-periodic surfaces, known as cubic C(Y) and a new hexagonal surface based on two nets

known as qtz and qzd, and discuss their distinct structural motifs inducing chirality. We present results for the

coupling of circularly polarised light to dielectric realisations of these structures, by the band structure analysis

of [2] and by scattering matrix methods [4]. Implications for metallic metamaterials based on these structures

are discussed.

Fig. 1: The C(Y) minimal surface (left) has cubic symmetry and is chiral. It is a perfect example for a structure that has two

distinct chiral structural elements that can couple differently to light and/or induce different photonic response. These are

double helices around the 43 screw axes (middle) and chiral “dog-bone” stackings along the 41 axes (right).

References [1] G.E. Schröder-Turk, S. Wickham, H. Averdunk, F. Brink, J.D. Fitz Gerald, L. Poladian, M.C.J. Large, S.T. Hyde, “The chiral structure of porous

chitin within the wing-scales of Callophrys rubi”, J. Struct. Biol. 174, 290-295 (2011).

[2] M. Saba, M. Thiel, M.D. Turner, S.T. Hyde, M. Gu, K. Grosse-Brauckmann, D.N. Neshev, K. Mecke, and G.E. Schröder-Turk, “Circular

Dichroism in Biological Photonic Crystals and Cubic Chiral nets”, Phys. Rev. Lett 106, 103902 (2011).

[3] M. Turner, G.E. Schröder-Turk, and M. Gu, “Fabrication and characterization of three-dimensional biomimetic chiral composites”, Optics

Express 19(10), 10001 (2011).

[4] D.M. Whittaker & I.S. Culshaw, “Scattering-matrix treatment of patterned multilayer photonic structures”, Phys. Rev. B 60, 2610 (1999)


11


Super-resolution photoinduction-inhibited nanofabrication based on the two-photon

absorption process

Yaoyu Cao1, Zongsong Gan 1, Richard A. Evans 2, and Min Gu 1 1Centre for Micro-Photonics and Centre for Ultrahigh bandwidth Devices for Optical Systems

(CUDOS), Faculty of Engineering and Industrial Science, Swinburne University of Technology,

Hawthorn, VIC 3122 2CSIRO Molecular and Health Technologies, Clayton South, Victoria 3169

Phone: (03)92144735

E-Mail: [email protected]

We demonstrate the SPIN technique based on two-photon absorption process, which is able to produce the dot and the line

of the feature size of 33 nm and 32 nm, equal to /24 and /25, respectively.

The emerging super-resolution photoinduction-inhibtited nanofabrication technique (SPIN) has demonstrated

impressive feature size reduction down to the nano-scale in the field of the direct laser writing. The key idea is

to introduce a second laser beam with a Gauss-Laguerre “doughnut” mode to locally inhibit the resist

polymerisation. With employing the process of the photogeneration of inhibitor radicals [1], the feature size of

40 nm has been realized in the single-photon SPIN technique [2] by fabricating dots on the cover slip. However,

it has inherent drawbacks in the fabrication of three-dimensional structures.

As for the two-photon fabrication technique, which is well known for its ability in the fabrication of three-

dimensional mircostructures, there exists a great material challenge to achieve photoinitiation and

photoinhibition simultaneously in the photoresist by the irradiation of the inhibiting laser beam and the

initiating beam. In this paper, we demonstrate the SPIN technique based on two-photon absorption process. We

applied a femtosecond pulsed laser beam at a wavelength of 800 nm to initiate the polymerisation and a CW

laser beam at a wavelength of 375 nm to activate the inhibitor. In this case, we have achieved dots of 33 nm and

lines of 32 nm, which is 1/24 and 1/25 of the wavelength of the initiating laser beam, respectively, as shown in

Fig. 1.

Figure 1 (a) Dot sizes are plotted as a function of the exposure time. (b) The SEM image of polymer dots fabricated with the

e

time of 10 ms. (c) Linewidths are plotted as a function of the scanning speed. (d) The SEM image of polymer lines fabricated

with the exposure of initiating laser and inhibiting laser beams of the power levels of 18 mW and 0.6 mW, at the scanning

speed of 140

References [1] T. F. Scott, B. A. Kowalski, A. C. Sullivan, C. N. Bowman, and R. R. Mcleod, “Two color single photon photoinitiation and photoinhibition for

subdiffraction photolithography”, Science, 324, 913, (2009).

[2] Y. Y. Cao, Z. S. Gan, B. H. Jia, R. A. Evans and M. Gu, “High-photosensitive resin for super-resolution direct-laser-writing based on photoinhibited

polymerization”, Opt. Express, 18, 19486, (2011).

a b

50 nm

33nm

c d


12


Nanoantennas for Efficient Broadband Unidirectional Emission Enhancement

Isabelle Staude


Nonlinear Physics Centre, Research School of Physics & Engineering,

Australian National University

Phone: (02) 6125 1006


Plasmonic nanoantennas have become a subject of considerable theoretical and experimental interest [1]. Numerous

potential applications of nanoantennas have been proposed including optical communication, nonclassical light emission,

and sensing. We here review our recent theoretical and experimental activities on this emerging topic, in particular on

novel designs for efficient broadband unidirectional emission enhancement.

Arrayed nanoantennas like Yagi-Uda and log-periodic architectures downscaled to nanometric dimensions

offer high directivity and strong emission enhancement at the same time [2]. However, as their bandwidth is

compromised by their unidirectionality they are intrinsically narrowband. To overcome this problem we

propose and study a novel plasmonic nanoantenna composed of arrays of equally spaced nanorods of

gradually varying length as depicted in Fig. 1 (a) [3-5]. Our theoretical results on nanoantenna performance are

summarized in Fig. 1 (b)-(d), corresponding experimental structures fabricated via electron-beam lithography

are presented in Fig. 1 (e)-(g). As evidenced by our numerical calculations this antenna design allows for

unidirectional emission enhancement in a broad operating band between 1.32 m and 1.65 m.

We acknowledge financial support by the Australian Research Council. Fabrication Facilities used in this

work are supported by the Australian National Fabrication Facility.

References [1] L. Novotny and N. van Hulst, “Antennas for light,” Nature Photon. 5, 83-90 (2011).

[2] G. Curto et al., “Unidirectional Emission of a Quantum Dot Coupled to a Nanoantenna,” Science 4, 930–933 (2010).

[3] I. S. Maksymov et al., “Multifrequency tapered plasmonic nanoantennas,” accepted Opt. Commun (2011).

[4] I. S. Maksymov, A. R. Davoyan, and Yu. S. Kivshar, “Enhanced emission and light control with tapered plasmonic nanoantennas,” Appl. Phys.

Lett. 99, 083304 (2011).

[5] A. E. Miroshnichenko et al., “An arrayed nanoantenna for broadband light emission and detection,” Phys. Status Solidi RRL 5, 347–349 (2011).

Fig. 1: (a) Schematic of an arrayed nanoantenna excited by an emitter via one of the possible excitation sites. (b-d)

Operating wavelength, radiation efficiency and front-to-back ratio as a function of the excitation site n. (e) Scanning

electron micrographs of the fabricated nanoantennas with different nanorod length variations; (f) shows a close-up of

the highlighted region, (g) an oblique-incidence view.

13


Modal methods and Impedance for nanoplasmonic structures and metamaterials

K.B. Dossou1, L.C. Botten1, C.G. Poulton1, R.C. McPhedran2 and C. M. de Sterke2

Centre for Ultrahigh bandwidth Devices for Optical Systems 1School of Mathematical Sciences, University of Technology, Sydney (UTS)

2School of Physics, University of Sydney

Phone: (02) 95144370

Email: [email protected], [email protected]

We discuss new, quick and accurate methods for modeling metamaterial and nanoplasmonic structures. The structures

considered consist of layers, with each layer in turn consisting of an array of elements of arbitrary composition and shape.

We present results for the computation of scattering and absorption in these structures and discuss how the formulation

can be used to generalize concepts of impedance to metamaterials.

Metamaterials and nanoplasmonic structures usually contain lossy, highly dispersive elements, such as thin

strips of metal, that can be structured with a scale size several times smaller than the wavelength of the medium

in which these elements are embedded. Although it is possible to model these structures in three dimensions

using purely numerical tools relying on Finite Differences or Finite Elements, such simulations often do not

elucidate the physics of the light propagation in these structures, and are in addition numerically expensive.

Here, we present a series of semi-analytical models that are specifically designed to model lossy, dispersive

nanoplasmonic and metamaterial structures in three dimensions1,2. These models combine the advantages of

both purely numerical methods and theoretical analysis, using each approach in the region where it is most

effective. The semi-analytical nature of the approach results in methods that are quick, accurate, and give

extensive physical insight into the importance of the various absorption and scattering mechanisms involved.

The overall approach used is to divide the structure into a number of layers (Fig. 1a); the modes of each layer

are computed numerically using a in-house Finite Element method. These modes are then used as a basis for the

expansion of the complete problem, with the connection between the layers given by a generalization of the

theory of thin films. The material absorption and dispersion can be taken into account rigorously, and the

transmission and absorption through the structure can be rapidly computed (Fig. 1b). Our formulation can be

applied to array elements of arbitrary composition and shape.

Fig. 1. a) Schematic of nanowire array s b) Contour plot of the absorptance versus the wavelength and nanowire height.

Such a plot would be exceedingly expensive to generate with conventional numerical tools.

The formulation enables the generalization of the concept of impedance to metamaterials and periodic

nanoplasmonic systems. Impedance is a key concept for the coupling of light into complex structures; we

present the generalization of this quantity to 2D periodic structures and discuss how this may be further

extended to lossy, 3D systems.

[1] K.B. Dossou, L.C. Botten, A.A. Asatryan, B.C.P. Sturmberg, M.A. Byrne, C.G. Poulton, R.C. McPhedran, and C.M. de Sterke, “Modal

formulation for diffraction by absorbing photonic crystal slabs,” Submitted to JOSA B.

[2] B. C. P. Sturmberg, K. B. Dossou, L. C. Botten, A. A. Asatryan, C. G. Poulton, C. M. de Sterke, and R. C. McPhedran, “Modal analysis of

enhanced absorption in silicon nanowire arrays,” Opt. Express, vol. 19, A1067–A1081 (2011).


14

TERABIT PER SECOND, Thursday, 2 February

SESSION SCHEDULE

Science Leader

Arthur Lowery

Professor and Head, Department of Electrical

and Computer Systems Engineering, Monash

University


Project Leader

Mark Pelusi

ARC Future Fellow, School of Physics, The

University of Sydney

2011 Project milestone achievements &

2012 goals

Arthur Lowery

OFDM signal processing achievements

& 2012 goals

Invited Speaker

Wolfgang Freude

Professor, Institute of Photonics and Quantum

Electronics, Karlsruhe Institute of Technology

Software-defined reconfigurable real-

time optical transmitters and receivers

Steve Madden


Nonlinear waveguides: 2011

achievements & 2012 goals

Yvan Paquot

Ph.D. Candidate, School of Physics, The


Tb/s automatic distortion compensation

using nonlinear optics

Jochen Schröder

ARC DECRA Fellow, School of Physics, The


All-optical discrete Fourier transform for

demultiplexing OFDM signals

Chad Husko



Ultracompact all-optical XOR logic in

slow-light silicon photonic crystal

waveguides

Invited Speaker

Alfredo de Rossi

Thales Research and Technology

Photonic Crystals for processing digital

and analog optical signals

15


Terabit per second project: Summary of 2011 achievements & 2012 goals

M. Pelusi


School of Physics, The University of Sydney

Phone: +61-2-9351-7697


A summary of the Terabit per second Flagship project 2011 achievements and 2012 target milestones is presented.

Highlight achievements in 2011 include all-optical signal processing using highly nonlinear chip scale devices

and the Waveshaper instrument from our partner investigator, Finisar. Demonstrations include using the slow

light effect in a silicon photonic crystal waveguide for enabling high-speed all optical logic [1] (Fig. 1(a)), and

switching [2] in ultra-compact, micron scale devices. Nanowire waveguides fabricated from silicon [3] or

chalcogenide [4] materials also demonstrated their capability for high-speed logic. A silicon nanowire was also

used to demonstrate dispersion monitoring of a 640 Gb/s DPSK signal [5]. Chalcogenide glass waveguides have

also demonstrated higher-order dispersion monitoring of 1.28 Tbaud per second optical signals in an automated

feedback dispersion-optimization circuit [6] (Fig. 1(b)). The capability of a Waveshaper instrument to enable

noise monitoring of ultra-fast 1.28 Tbaud per second optical signals was also shown [7].

In 2012, the goals will be to further demonstrate the energy efficient, and broadband capability of chip

scale devices, and the Finisar Waveshaper in more advanced signal processing functions to address key issues in

the generation, transmission and detection of high-bit rate signals encoded with advanced modulation formats.

(a) (b)

Fig. 1: (a) Slow light in nonlinear silicon waveguide for enabling all-optical logic of 40 Gb/s optical signals in a micron scale waveguide [1],

and (b) system configuration for using highly nonlinear chalcogenide glass waveguide in combination with the Finisar Waveshaper for

enabling simultaneous dispersion monitoring and automated feedback dispersion optimization of a 1.28 Tb/s signal [6].

References

[1] Husko, C., Vo, T. D., Corcoran, B., Li, J., Krauss, T. F., and Eggleton, B. J., "Ultracompact all-optical XOR logic gate in a slow-light

silicon photonic crystal waveguide," Opt. Express 19, 20681-20690 (2011).

[2] Corcoran, B., Pelusi, M.D., Monat, C., Li, J., O’Faolain, L., Krauss, T.F., and Eggleton, B.J., "Ultracompact 160 Gbaud all-optical

demultiplexing exploiting slow light in an engineered silicon photonic crystal waveguide," Opt. Lett. 36, 1728-1730 (2011).

[3] Li, F., Vo, T.D., Husko, C., Pelusi, M., Xu, D-X., Densmore, A., Ma, R., Janz, S., Eggleton, B.J., and Moss, D.J., "All-optical XOR logic

gate for 40Gb/s DPSK signals via FWM in a silicon nanowire," Opt. Express 19, 20364-20371 (2011).

[4] Vo, T.D., Pant, R., Pelusi, M.D., Schröder, J., Choi, D.-Y., Debbarma, S.K., Madden, S.J., Luther-Davies, B. and Eggleton, B.J.,

"Photonic chip-based all-optical XOR gate for 160 Gbit/s DPSK signals,", Optics Letters, Vol. 36, Issue 5, pp. 710-712 (2011).

[5] Vo, T., Corcoran, B., Schroder, J., Pelusi, M.D., Xu, D.X., Densmore, A., Ma, R., Janz, S., Moss, D.J., and Eggleton, B.J., "Silicon chip

based real-time dispersion monitoring for 640 Gbit/s DPSK signals,", J. Lightwave Technol., vol.29, no.12, pp. 1790 – 1796, (2011).

[6] Paquot, Y., Schröder, J., Van Erps, J., Vo, T.D., Pelusi, M.D., Madden, S., Luther-Davies, B., and Eggleton, B.J., "Single parameter

optimization for simultaneous automatic compensation of multiple orders of dispersion for a 1.28 Tbaud signal," Opt. Express 19,

25512-25520 (2011).

[7] Schroeder, J., Brasier, O., Van Erps, J., Roelens, M., Frisken, S., and Eggleton, B.J.,"OSNR monitoring of a 1.28 Tbaud signal by

interferometry inside a Wavelength Selective Switch," J. Lightwave Technology, vol.29, no.10, pp. 1542 - 1546 (2011).

16


17


Nonlinear Waveguides: 2011 Achievements and 2012 Goals

Steve Madden


Laser Physics Centre, ANU, Canberra

Phone: +61-2-6125-8574



18


Tb/s automatic distortion compensation using nonlinear optics

Yvan Paquot1, Jochen Schröder1, Jürgen Van Erps1,2, Trung D. Vo1,

Mark D. Pelusi1, Steve Madden3, Barry Luther-Davies3 and Benjamin J. Eggleton1

1Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS),

Institute of Photonics and Optical Science (IPOS)

School of Physics A28, University of Sydney, NSW 2006, Australia, 2Vrije Universiteit Brussel, Brussels Photonics Team, Dept. of Applied Physics

and Photonics, Pleinlaan 2, 1050 Brussel, Belgium, 3CUDOS, Laser Physics Centre, Australian National Univ., Canberra A.C.T. 0200, Australia

[email protected]

We demonstrate that distortions due to multiple orders of dispersion can be tracked using a chip-based all-optical RF

spectrum analyzer and compensated automatically with a spectral pulse shaper. Our experimental system was able to

simultaneously compensate for 2nd, 3rd and 4th orders of dispersion fluctuations on a single channel OTDM link at 1.28Tb/s.

High bandwidth OTDM signals [1] are increasingly susceptible to impairments that can be detected using an

ultra-broadband impairments monitor. This monitor, a chip-based all-optical spectrum analyzer [2], can then be

used to control a distortion compensator [3]. We show that this approach stays valid for automatic simultaneous

compensation of multiple independent impairments by running continuously a multivariate optimization

algorithm on a single scalar parameter. We apply that method to automatic and simultaneous compensation of

the second, third and fourth orders of dispersion (β2, β3 and β4) for a 1.28 Tb/s single channel OTDM signal.

Fig. 1: Automatic dispersion compensation

scheme: the 1.28 Tbaud transmitter is

followed by a link emulating both initial

residual dispersion and dispersion

fluctuations. The combination of a signal

monitor with a dispersion compensator [4]

allows for automatic compensation of those

fluctuations simultaneously for β2, β3 and β4. The compensation scheme is based on maximizing the 1.28 THz tone power of

the RF spectrum of the signal (right insert). The optimization algorithm keeps the tone power optimum and allows for

recovering even from sharp dispersion changes (bottom graph).

References [1] H. Hansen Mulvad, L. Oxenlø we, M. Galili, A. Clausen, L. Gruner-Nielsen, and P. Jeppesen, “1.28 Tbit/s singlepolarisation serial OOK

optical data generation and demultiplexing,” Electronics Letters 45, 280–281 (2009).

[2] M. Pelusi, F. Luan, T. D. Vo,M. R. E. Lamont, S. J. Madden, D. A. Bulla, D.-Y. Choi, B. Luther-Davies, and B. J. Eggleton, “Photonic-chip-

based radio-frequency spectrum analyser with terahertz bandwidth,” Nature Photonics 3, 139–143 (2009).

[3] J. Van Erps, J. Schroeder, T. Vo, M. Pelusi, S. Madden, D. Choi, D. Bulla, B. Luther-Davies, and B. Eggleton, “Automatic dispersion

compensation for 1 . 28Tb/s OTDM signal transmission using photonic-chip-based dispersion monitoring,” Optics Express 18, 25415–25421 (2010).

[4] M. A. F. Roelens, S. Frisken, J. A. Bolger, D. Abakoumov, G. Baxter, S. Poole, and B. J. Eggleton, “Dispersion Trimming in a Reconfigurable

Wavelength Selective Switch,” Lightwave 26, 73–78 (2008).

19


All-optical discrete Fourier transform for demultiplexing OFDM signals

Jochen Schröder



Phone: +61-2-9036 9430


20


Ultracompact all-optical XOR logic in slow-light silicon photonic crystal waveguides C. Husko1, T. D. Vo1, B. Corcoran1, J. Li2, T.F. Krauss2, B. J. Eggleton1

1Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS), Institute of Photonics and Optical Science,School of Physics, The University of

Sydney, NSW 2006, Australia 2 School of Physics and Astronomy, University of St Andrews, St Andrews, Fife KY16 9SS, United Kingdom We demonstrate ultracompact chip-based all-optical exclusive-OR (XOR) logic via slow-light enhanced four-wave

mixing in a silicon photonic crystal waveguide. The device is error-free for 40 Gbit/s differential phase shift keying

(DPSK) signals. All-optical nonlinear signal processing is advancing rapidly. All-optical logic functions are one of the

components expected to compose such a system [1]. To this end, a variety of operations, such as all-optical logic

in a 50 mm periodically poled lithium niobate device, have been realized [2]. Here we exploit four-wave mixing

(FWM) to demonstrate an all-optical exclusive-OR (XOR) logic gate with 40 Gbit/s return-to-zero (RZ)

differential phase shift keying (DPSK) signals. Slow-light enhancement of the optical signal in the photonic

crystal waveguide (PhCWG) [3,4], Fig. 1(a), enables ultracompact logic operation (396 m) and suggests

potential device integration in future all-optical communication systems.

Fig. 1 (a) Slow-light enhanced optical signal in the PhCWG (b) All-optical XOR device schematic (c) Temporal waveforms of

the two data channels and XOR product (d) Bit-error rate measurements 40 Gb/s DPSK signals. Inset: XOR eye diagram The all-optical XOR operation arises from slow-light enhanced non-degenerate FWM of two phase encoded data

signals at 1 and 2 with a CW probe at p. This generates an XOR output at the idler wavelength i, Fig. 1(b).

The data signal phases mix according to: : i2 +p 1 [5], with the CW signal p contributing “0”. Thus the

generated idler contains the 0 or states at the output of the XOR gate, “0” and “2” being equivalent. The

device is a dispersion engineered silicon PhCWG air-suspended structure with measured group index ng ~ 30

over a 12 nm bandwidth, and near constant dispersion, ensuring efficient phase matching. Linear propagation

loss in the slow light region was 65 dB/cm [3,6] with a total insertion loss of ~ -11.8 dB.

Two 40 Gbit/s RZ-DPSK signals (1 =1538.1 nm and 2 =1539.5 nm) were mixed with the CW beam, (Pave ~

10mW coupled for each signal) and coupled to the chip. We measured negligible two-photon absorption at this

power level. The generated XOR idler is extracted and demodulated before detection by a 40 Gbit/s receiver.

Figure 1(c) shows the demodulated temporal waveforms of the data and XOR channels. One can see the FWM

idler is the XOR output from the two input DPSK channels. Slow-light enables the XOR operation to be

completed at an estimated energy of ~ 1 pJ/bit over a 396 m length, nearly two orders of magnitude shorter

than other nonlinear media [2]. Bit-error-rate (BER) measurements, Fig. 1(d), demonstrate ‘error-free’ (BER<10-9)

operation of the XOR product (inset: eye diagram of the XOR signal) with a ~ 2.8 dB power penalty, contributed

to the small energies in the PhCWG. These results could be improved with better collection efficiency, or an

ultralow noise amplifier.

We have demonstrated an ultra-compact all-optical XOR gate using non-degenerate four-wave mixing in a

dispersion-engineered photonic crystal waveguide for 40 Gbit/s DPSK signals. Error-free XOR operation was

achieved with a 2.8 dB power penalty. Operation with faster data rates should be possible with broader

bandwidth devices. Compact device operation (396m) suggests the potential for integration on a photonic chip.

References [1] A.Willner et al, IEEE J. Sel Top Quantum Electron. 17 320 (2010) [2] J. Wang et al, Opt. Lett. 33 1419 (2008)

[3] J. Li et al, Opt. Express 19, 4458, (2011) [4] B. Corcoran et al, Nature Photon. 3, 206 (2009)

[5] G.P. Agrawal, Nonlinear Fiber Optics, (Academic Press, 2001) [6] C. Husko et al, Opt. Express 19, 20681 (2011)

-34 -31 -28 -25

-9

-6

-3

Received Power (dBm)

BE

R

Ch.1 - B2B

Ch.2 - B2B

XOR

2.8 dB

(c)(c) (d) (a)

(b)

21


22

MID-INFRARED PHOTONICS, Thursday, 2 February

SESSION SCHEDULE

Science Leader

Steve Madden


Overall aim and science goals

Project Leader

Stuart Jackson

ARC Queen Elizabeth II Fellow, Associate

Professor, School of Physics, The University of

Sydney

Progress with respect to 2011 milestones

Darren Hudson

Research Fellow, School of Physics, The


Science Report for 2011

David Moss

Associate Professor, School of Physics, The


Silicon waveguides for the MIR

Stuart Jackson

Milestones for 2012

23


Mid-Infrared Project Overview

Stuart Jackson


School of Physics, University of Sydney

Phone: +61 02 9114 0772


Mid-wave infrared photonics is a burgeoning research area in modern optics in which CUDOS embarked in

2011. The growing international interest stems from the large variety of applications particularly in the areas of

sensing that are increasingly being developed for medicine, defence and environmental monitoring. In CUDOS,

we are creating new light sources, new waveguides and new detectors in both fibre and planar waveguide

formats in order to meet the diverse needs of the end user community.

Our first year in this field was filled with much activity in building up a variety of pump, probe and diagnostic

tools to be used throughout the project. We currently have one fulltime PhD student and one fulltime Research

Fellow dedicated to the project with a smaller number of people from within CUDOS making part-time

commitments. In 2012 we intend to grow the research personnel to reflect the growing activities within the

project.

In this presentation we will summarise the 2011 outcomes from the project and we will re-iterate the project

goals and milestones. We will also layout the milestones for 2012.

24


Mid-Infrared Science Report for 2011

Darren D. Hudson



Phone: +61 02 9351 7697


The research efforts regarding generating novel laser-based sources in the mid-IR wavelength range will be

reviewed in this talk. In particular, two main approaches were investigated: spectral generation through

nonlinear processes and high power laser sources based on rare-earth doped fibers.

The efforts to extend the use of chalcogenide tapered optical fiber for supercontinuum generation [1] into the

mid-IR wavelength range yielded valuable information into the guidance properties of the chalcogenide fiber at

long wavelengths. Future directions of this effort include creating supercontinuum using a taper pumped by a

Thulium mode-locked laser operating at 1980 nm and tapering of chalcogenide based Photonic Crystal fiber for

supercontinuum generation centered at 3.4 m.

The construction of a variety of rare-earth doped fiber lasers in tunable, continuous-wave [2, 3] and Q-switched

configurations [4] has allowed for testing devices at new wavelength ranges and with high peak powers. A

Holmium/Praseodymium co-doped fiber laser was demonstrated with record efficiency, high power, and wide

tunability around the central wavelength of 2.85 m. This system represents a valuable tool for testing linear

characteristics of mid-IR based devices in a wavelength range that is inaccessible to standard Quantum Cascade

lasers. To access the nonlinear domain in the mid-IR wavelength range, another Ho/Pr co-doped fiber laser was

constructed in a Q-switched cavity configuration. This system allows for a tunable repetition frequency and 140

ns pulses. Experiments implementing this laser as a pump source will be reviewed.

25


Silicon-on-Sapphire Waveguides for Linear and Nonlinear Applications from the Near to

Mid IR

David J. Moss


Phone: +61 02 9351 3979


I will briefly review our recent results for silicon-on-sapphire (SOS) nanowire waveguides for the near IR to mid

IR as well as challenges and plans for both the near term and longer future for this new and promising platform

for photonic integrated circuits.

26

QUANTUM INTEGRATED PHOTONICS, Friday, 3 February

SESSION SCHEDULE

Science Leader

Mike Steel

Associate Professor, Department of Physics &

Astronomy, Macquarie University

Introduction

Project Leader

Chunle Xiong



2011 achievements and 2012 goals &

milestones

Matt Collins

Ph.D. Candidate, School of Physics, The


Impact of Cooling on Raman Scattering

in an As2S3 Correlated Photon Pair

Source

Chunle Xiong

Slow-light enhanced photon-pair

generation

Graham Marshall

Research Fellow, Faculty of Science,

Macquarie University

Recent activities in guided wave

quantum circuits

Alex Solntsev

Ph.D. Candidate, Nonlinear Physics Centre,

ANU

Quantum optics in nonlinear

waveguide arrays

Invited Speaker

John Harvey

Professor of Physics, University of Auckland

and Principal, Southern Photonics

Fibre Optical Parametric Oscillators in

the near Infra Red Wavelength region

Invited Speaker

Mark Thompson

Research Fellow, Departments of Physics &

Electrical & Electronic Engineering, University

of Bristol

Advances in integrated quantum

photonics circuits

Invited Speaker

John Sipe

Professor, Department of Physics, University of

Toronto

Classical and quantum nonlinear

photonics: calculations made easier

27


2011 Achievements and 2012 Goals & Milestones

C. Xiong1

1Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS), School of Physics,

University of Sydney, NSW 2006

Phone: +61 2 90369430 Email: [email protected]

We have had a very successful and exciting year on the Quantum Integrated Photonics project during 2011. We

have established new capability for photonic quantum experiments. These include single-photon detection

systems, quantum device fabrication systems and new students and postdocs. Towards the goal of quantum

integration, we have demonstrated quantum-correlated photon-pair generation in various nonlinear platforms

such as the ultra-compact silicon photonic crystal waveguides. We have proposed and simulated a framework of

simultaneous photon-pair generation and quantum walks in nonlinear waveguide arrays. Because of our hard

work, we have delivered high performance in terms of KPIs. We have published 7 papers in prestigious journals

such as Physical Review Letters, Applied Physics Letters, New Journal of Physics, Optics Letters and Optics

Express. These represent extensive and successful CUDOS cross-node collaboration and the collaboration

between CUDOS researchers and our partner investigators.

In 2012 we will step further towards quantum integration. Our ambition is to demonstrate hybrid integration of

quantum sources and quantum process/logic circuits. This includes the implementation of photon correlation in

3D devices, CNOT logic circuits at 1550 nm, on-chip quantum interference, quantum state translation and

quantum walks in waveguide arrays.


28


Impact of Cooling on Raman Scattering in an As2S3 Correlated Photon Pair Source

Matthew J. Collins, Alex S. Clark, Chunle Xiong, Eric Magi and Benjamin J. Eggleton



Phone: +61 2 9531 5978


The generation of correlated photon pairs at telecommunication wavelengths is attractive for quantum

communication, requiring sources that are both bright and low noise. Recently a chalcogenide glass waveguide,

namely As2S3, was presented as an attractive alternate platform for correlated photon pair generation by SFWM,

however a limit in performance was observed due to spontaneous Raman scattering (SpRS). We investigated the

impact of cooling on SpRS in an As2S3 photon pair source by measuring the photon statistics of correlated pair

generation as well as classically measuring the change in Raman gain at a large detuning from the pump. We

show that the reduction in SpRS and associated improvement in the photon statistics of As2S3 correlated pair

sources is only significant in the region close to the pump.

29


Slow-light Enhanced Correlated Photon-pair Generation

C. Xiong1, C. Monat1, 2, M. Collins1, A. Clark1, C. Grillet1, G. Marshall3,

M. J. Steel3, J. Li4, L. O'Faolain4, T. F. Krauss4 and B. J. Eggleton1 1Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS), School of Physics,

University of Sydney, NSW 2006 2Institut des Nanotechnologies de Lyon, Ecole Centrale de Lyon,

36 Avenue Guy de Collongue, 69134 Ecully, France 3CUDOS, Department of Physics & Astronomy, Macquarie University, NSW 2109, Australia

4School of Physics and Astronomy, University of St Andrews, Fife, KY16 9SS, UK

Phone: +61 2 9036 9430


As quantum information is increasingly demanding many-photon input states, a mature silicon source might

eventually contain hundreds of individual pair generation units combined with intelligent routing as the

photons appear. To make this a reality, a more compact and efficient individual generation unit is a critical

development. Here we report the generation of correlated photon pairs in the telecom band using spontaneous

four-wave mixing (SFWM) from a 96 µm silicon photonic crystal waveguide operating in a dispersion-

engineered slow light regime. The slow-light enhancement of SFWM critically decreases the path length of the

device by two orders of magnitude, making it the most compact emitter of quantum correlated photon pairs yet

reported. The coincidence to accidental ratio, a key measurement of the quality of a photon-pair source, was

maximum 26, making this source immediately applicable to many photonic quantum technologies.


30


Recent activities in guided wave quantum circuits

Thomas D. Meany, Simon Gross, Graham D. Marshall, M. J. Steel, and Michael J. Withford

Centre for Ultrahigh bandwidth Devices for Optical Systems, MQ Photonics Research Centre,

Department of Physics and Astronomy, Macquarie University, North Ryde, NSW 2109, Australia

Phone: +61-2-9850-7583


From the first demonstrations of quantum interference in direct laser written waveguide ‘chips’ the direct-write platform

has been shown to enable high-fidelity circuit operation. We are now extending this platform to enable new devices for

quantum simulation and quantum logic applications and we will review some of these activities in this short presentation.

Central to the high performance operation of integrated quantum circuitry is the ability of a waveguide circuit to

perform interference [1] with high contrast. To achieve this we require the integrated optical platform to

manipulate and guide light without compromising the input polarization state and with as low a loss as

possible. In our efforts to create waveguide circuits that can perform complex quantum logic operations or

simulate quantum processes that occur in nature we need to extend present direct-write technology into 3-

dimensions. This in turn requires additional studies of the waveguide parameters because the manufacturing

process creates waveguides that are not perfectly horizontally and vertically symmetric. After initial successes

with 2D waveguide circuits fabricated using a low repetition rate ultrafast laser [2] we are now developing

processing recipes to create waveguides using a very high repetition rate laser system that can fabricate 3D

devices many orders of magnitude quicker [3]. An important parameter of study we’ve been exploring is the

effect of waveguide-pair orientation on evanescent coupling and we created samples such as that shown in

Figure 1 to measure this and we’ll give a summary of these results and their implications in the presentation.

Figure 1 – Micrograph end view of test arrays of waveguides written with a high

repetition rate laser. The writing laser was incident from the top. These samples were

used to test the effect of waveguide pair orientation (top – horizontal,

middle – vertical, bottom at 45°) on coupling constant.

One of the future goals of this work is to create quantum logic gate devices that can be directly integrated with

the single-photon sources being developed within the CUDOS Quantum Integrated Photonics flagship project.

The vision of this work is to directly couple the photon source with the logic chip thereby creating an integrated

and compact device. In this first instance we intend to integrate a controlled-NOT gate with its source.

[1] C. K. Hong et al., "Measurement of subpicosecond time intervals between two photons by interference," Phys. Rev. Lett., vol. 59, pp. 2044-2046

(1987).

[2] G. D. Marshall et al., "Laser written waveguide photonic quantum circuits," Optics Express, vol. 17, no. 15, pp. 12546-12554 (2009).

[3] C. Miese et al., “Femtosecond laser direct-writing of waveguide Bragg gratings in a quasi cumulative heating regime,” Optics Express, vol. 19,

no. 20, pp. 19542-19550 (2011).

31


Quantum Optics in Nonlinear Waveguide Arrays

A. S. Solntsev1, A. A. Sukhorukov1, D. N. Neshev1, F. Setzpfandt2, M. Gräfe2, R. Keil2,

A. Tünnermann2, S. Nolte2, A. Szameit2, T. Pertsch2 and Yu. S. Kivshar1 1Centre for Ultrahigh bandwidth Devices for Optical Systems

Nonlinear Physics Centre, RSPE, Australian National University 2Institute of Applied Physics, Friedrich-Schiller-University Jena, Germany

Phone: +61-2-6125-9075


We study photon pair generation in nonlinear waveguide arrays and demonstrate the feasibility of these photonic structures

for generation of unique, strongly non-classical and easily tunable spatial quantum states. We describe such effects in

waveguide arrays with quadratic and cubic nonlinearities, as well as demonstrate the possibility to simulate photon pair

generation by using linear two-dimensional waveguide array.

As quantum optics grows and develops, new sophisticated optical schemes require an increasing number of

optical elements. Integrated photonic circuits have the capacity to provide a solution to this challenge, as they

are intrinsically scalable and interferometrically stable. Integrated realization of multi-photon entanglement [1],

quantum factoring algorithms [2], and polarization entanglement [3] has already been demonstrated. One of

particularly interesting structures in integrated photonics is the waveguide array. Recently waveguide arrays

have been shown to generate unusual and strongly non-classical correlations of photon pairs propagating in the

regime of quantum walks [4]. Combining quantum walks with photon pair generation in nonlinear waveguide

arrays has opened the possibility for enchained spatial quantum state control and improved clarity of spatial

correlations [5]. In this work we have experimentally confirmed the feasibility of photon-pair generation

through spontaneous parametric down-conversion in waveguide arrays with quadratic nonlinearity [Fig. 1(a)].

We have also demonstrated that waveguide arrays with cubic nonlinearity [Fig. 1(b)] allow for much more

flexible quantum state tuning due to spontaneous four-wave mixing phase-matching being affected by cross-

phase modulation. Finally, we have experimentally realized an optical platform [Fig. 1(c)] where linear

evolution of classical light simulates bi-photon generation through spontaneous parametric down-conversion

and correlated quantum walks in waveguide arrays, including the regime of violated Bell's inequality.

Fig. 1: (a) A waveguide array with quadratic nonlinearity with pump staying in the central waveguide. (b) A waveguide

array with cubic nonlinearity with pump propagating in the regime of discrete diffraction. (c) Sketch of 1D quadratic

nonlinear waveguide array with pump coupled to the edge waveguides and output detectors of generated bi-photons.

In conclusion, we have demonstrated that waveguide arrays represents a flexible platform for generation of

various bi-photon spatial quantum states, and that higher dimensional linear waveguide arrays can sometimes

emulate this behavior. We anticipate that our results will open new opportunities for integrated quantum

photonics.

References [1] J. C. F. Matthews, A. Politi, A. Stefanov, and J. L. O’Brien, Nature Photonics 3, 346 (2009).

[2] A. Politi, J. C. F. Matthews, and J. L. O’Brien, Science 325, 1221 (2009).

[3] L. Sansoni, F. Sciarrino, G. Vallone, P. Mataloni, A. Crespi, R. Ramponi, and R. Osellame, Phys. Rev. Lett. 105, 200 (2010).

[4] A. Peruzzo, M. Lobino, J. C. F. Matthews et al., Science 329, 1500 (2010).

[5] A. S. Solntsev, A. A. Sukhorukov, D. N. Neshev, Y. S. Kivshar, Phys. Rev. Lett (2011) in press; arXiv :1108.6116.

32


Fibre Optical Parametric Oscillators in the near Infra Red Wavelength region

John Harvey

Physics Department, University of Auckland

Phone: +64 9923 8832


New developments in fibre Optic Parametric Oscillators include the development of high power (multi Watt)

sources, and the development of pulsed sources having an extended tunability up to 2 microns. The architecture

of these systems could be readily adapted to other fibre materials (and therefore further into the mid infra red

region), and to dual pumping schemes. Variants of the four wave mixing scheme used here can also potentially

provide wavelength translation into the visible region where efficient single photon detectors are available

33


Advances in Integrated Quantum Photonics Circuits

Mark G. Thompson, Damien Bonneau, Erman Engin, Alberto Politi, Jonathan C. F. Matthews,

Anthony Laing, Alberto Peruzzo, Konstantinos Poulios, Jasmin Meinecke, Pete Shadbolt,

Daniel Fry, Mirko Lobino, Jeremy L. O'Brien

Centre for Quantum Photonics, H. H. Wills Physics Laboratory & Department of Electrical and

Electronic Engineering, University of Bristol, Merchant Venturers Building, Woodland Road,

Bristol, BS8 1UB, UK


Integrated quantum photonic circuits offer a level of control, stability, miniaturization and scalability that far

surpasses any other optical implementation of quantum architectures. This approach has been used to realise

high fidelity operation of key quantum photonics components, such as on-chip two-photon quantum

interference and controlled-NOT logic gates. In this presentation we present new advancements including fast

manipulation of path and polarization encoded qubits, dynamically reconfigurable circuits for on-chip

entanglement generation and manipulation, quantum simulation of bosonic, fermonic and anyonic multi-

particle quantum walks, and new technologies for photon generation and manipulation including Lithium

Niobate, GaN and Silicon. These results represent key steps that are crucial for the development of practical

quantum photonic technologies for applications in quantum communication, metrology, simulation,

computation and fundamental science.


34


Classical and quantum nonlinear photonics:

Calculations made easier

M. Liscidini1, L.G. Helt2, and J.E. Sipe2

1Physics Department “A. Volta,” University of Pavia, via Bassi 6, I-27100 Pavia, Italy 2Department of Physics and Institute for Optical Sciences, University of Toronto, 60 St. George St.

Toronto, Ontario M5S 1A7 Canada


We present a simple and extremely flexible method for a description of classical and quantum nonlinear phenomena in

photonic systems. This approach is particularly suited to model integrated devices and photonic crystal structures.

While the guiding and confining of light in photonic structures can increase the efficiency of nonlinear processes,

a rigorous analysis of such phenomena is challenging. Even in the perturbative limit, the traditional calculation

of classical nonlinear processes in cavity or photonic crystal structures can be complicated. And in the quantum

regime, where a mode expansion is desirable if not essential, the introduction of quasi-modes for any but the

simplest resonant structures, together with the description of their coupling to input and output channels, is

tedious and difficult. Here we propose a new method that can be applied to an arbitrary structure, and uses as a

starting point stationary solutions of linear Maxwell equations that can be found either numerically or

analytically. This approach is ideal for studying classical and quantum nonlinear optics problems in integrated

devices, including photonic crystal cavities and waveguides. It harks back to the elementary theory of scattering

in quantum mechanics, where one can introduce asymptotic-in and asymptotic-out states. Here asymptotic-in

and -out fields are constructed that serve as the basis for the quantization of the electromagnetic field; linear

scattering is described as a unitary transformation between the amplitudes of the asymptotic-in and -out fields.

Nonlinear interactions can then be included. Artificial quasi-modes need not be introduced. Although this

strategy should be of use even in nonperturbative problems, we give a simple example from perturbative

nonlinear optics that shows how it simplifies not only quantum optics calculations, but even more traditional

classical calculations.

35

FUNCTIONAL METAMATERIALS, Friday, 3 February

SESSION SCHEDULE

Invited Speaker

Igal Brener

Nanophotonics Thrust Leader, Center for

Integrated Nanotechnologies, Sandia

National Laboratories, USA

Interactions between semiconductors

and planar metamaterials: active

infrared metamaterials

Science Leader

Yuri Kivshar

Distinguished Professor, Australian Federation

Fellow, Head, Nonlinear Physics Centre, ANU

Project Overview

David Powell

Research Fellow, Nonlinear Physics Centre,

ANU

Exotic nonlinear metamaterials

Alex Minovich

ARC Super Science Fellow, Nonlinear Physics

Centre, ANU

Liquid Crystal tunable optical fishnet

metamaterials

Mark Turner

Ph.D. Candidate, Centre for Micro-Photonics,

Swinburne University of Technology

Three-dimensional metamaterials

Project Leader

Dragomir Neshev

Associate Professor, ARC Queen Elizabeth II

Fellow, Nonlinear Physics Centre, ANU

2012 Project goals and milestones

Discussion

Invited Speaker

Nikitas Papasimakis

Leverhulme Advanced Research Fellow,

Optoelectronics Research Centre, University

of Southampton

Disordered metamaterials for light

localization and enhanced

nonlinearities

36


Fig. 1: (a) Schematic cross section showing thin film interface between

metallic SRR elements and a thin SiO2 layer. (b) the measured resonant

frequencies of the coupled modes compared to the analytical model for two

coupled oscillators. (c-e) Normal mode splitting simulated by FDTD as the

SiO2 layer is displaced from the SRR metamaterial elements: SiO2 in (c)

contact, (d) depth of 50nm, (e) depth=125nm.

(a)

(b)

(c)

(d)

(e)

Interactions between semiconductors and planar metamaterials: active infrared

metamaterials

Igal Brener

Sandia National Laboratories and Center for Integrated Nanotechnologies

Phone: +1-505-844-8097


We explore the coupling between metamaterial resonators and different types of thin layers with optical transitions

throughout the infrared. Examples are phonon transitions, highly doped semiconductor layers and engineered intersubband

transitions in heterostructures. These coupling mechanisms can be exploited for electrical tuning of infrared optical

metamaterials.

Planar metamaterials (or “metafilms”) offer a promising platform for new types of active optical devices.

Resonances in these metamaterial structures can be scaled by geometry and their spectral response is exquisitely

sensitive to the local dielectric environment which can be changed using a number of tunable dielectrics [1, 2].

Here we explore the interaction between metamaterial resonators and various dipole resonances and discuss

how to harness these for electrical tuning of metamaterials. An example of this strong coupling is shown in Fig.

1: Infrared phonons in dielectrics (such as SiO2) placed in proximity with metamaterial resonators can couple

strongly, leading to normal mode splitting similar to vacuum-Rabi splitting that occurs with optical emitters

coupled to microcavities. The amount of coupling can be altered through the design of the metamaterial

resonators, the proximity of the dielectric layer to the resonator, the dielectric film thickness, and the amount of

field overlap with the dielectric layer.[3]

Similar to the phonon case, we can use thin epitaxial

layers of either doped semiconductors or engineered

optical transitions in semiconductor

heterostructures. These layers can be tuned with an

applied bias either through depletion of carriers or

Stark shifting of optical transitions. I will show

several examples that use these semiconductor

approaches for electrically tunable metamaterials in

the mid IR.

Acknowledgements

This work was performed, in part, at the Center for

Integrated Nanotechnologies, a U.S. Department of

Energy, Office of Basic Energy Sciences user facility.

Sandia National Laboratories is a multi-program

laboratory managed and operated by Sandia

Corporation, a wholly owned subsidiary of

Lockheed Martin Corporation, for the U.S.

Department of Energy’s National Nuclear Security

Administration under contract DE-AC04-94AL85000.

References

1. H.-T. Chen, W. J. Padilla, J. M. O. Zide, et al., "Active terahertz metamaterial devices," Nature 444, 597-

600 (2006).

2. T. Driscoll, S. Palit, M. M. Qazilbash, et al., "Dynamic tuning of an infrared hybrid-metamaterial

resonance using vanadium dioxide," Applied Physics Letters 93, 024101 (2008).

3. D. Shelton, I. Brener, J. Ginn, et al., "Strong Coupling between Nanoscale Metamaterials and Phonons,"

Nano Letters (2011).

37


38


Liquid Crystal Tunable Optical Fishnet Metamaterials

Alexander Minovich


Nonlinear Physics Centre, RSPE, Australian National University

Phone: +61-4-61259076


We present our recent development on the tenability of optical fishnet metamaterials. In particular we show two ways to

achieve liquid crystal tunability of the fishnets: via hole mode and SPP resonances control. We demonstrate experimentally

a nonlinear optical response of a fishnet structure infiltrated with a liquid crystal.

Fishnet structure is one of the popular designs for achieving a broad band negative refractive index

accompanied by a high transmission [1]. Designing tunable metamaterials would increase the functionality of

such structures enabling them for broader applications. However, broad resonances in the fishnet geometry

require a significant refractive index change to obtain a substantial change of macroscopic properties. Liquid

Crystal (LC) media with their high anisotropy can provide the necessary value of the index change. Our

numerical study of fishnet structures shows that there are two ways for achieving the tunability. The geometrical

parameters of the metamaterial can be chosen such that there is a broad hole transmission peak in the region of

interest. In this case the effective index is mainly dependent on the changes inside the hole and it is possible to

achieve a gradual neff switching from negative to positive values {Fig. 1(a) (dashed line)]. On the other hand it is

possible to choose geometrical parameters in such a way that there is a narrow Extraordinary Optical

Transmission (EOT) peak in the range of interest. In this case the system is mainly sensitive to the index change

near gold surface due to relation of EOT and surface plasmon polaritons (SPP) and much more abrupt index

change is achievable (300 times enhancement) {Fig. 1(a) (solid line)].

Fig. 1: (a) Effective index change versus LC index value inside the hole for hole mode control case (dashed line) and at the

metal surface for SPP control case (solid line). (b) Nonlinear transmission of a fishnet structure with MgF2 dielectric layer

infiltrated with E7 liquid crystal at λ=1.55 μm. Inset: SEM image of the fishnet sample.

In addition, we fabricated a fishnet structure to realise the tunability via hole mode control experimentally. We

infiltrate the sample with a LC mix E7 from Merck. After that we illuminate the sample with a high intensity

focused laser beam and observe a nonlinear dependence of the transmission on the input power.

References [1] J. Valentine, S. Zhang, T. Zentgraf, E. Ulin-Avila, D. A. Genov, G. Bartal, and X. Zhang, “Optical Metamaterial Exhibiting Negative

Refractive Index," Nature 455, 376, (2008).

39


Three-dimensional metamaterials

Mark D. Turner1,2

1Centre for Micro-Photonics and CUDOS, Faculty of Engineering and Industrial Science,

Swinburne University of Technology, Australia, VIC 3122, Australia. 2CRC for Polymers, 8 Redwood Drive, Notting Hill, Australia, VIC 3168, Australia

Phone: 03 9214 4303


Here we show our recent developments on three-dimensional (3D) metamaterials, based on metallic biomimetic networks.

We will present theoretical analysis of these 3D metallic chiral networks showing circular dichroism and optical activity.

We shall also present our latest micro-fabrication results of these 3D metamaterials, as well as fabrication at the macro-scale

using 3D printing.

Previously we reported the fabrication and characterisation of chiral photonic crystals [1] whose design was inspired by

recent theoretical findings [2] of circular dichroism bands in the wing-scales of a butterfly. These micro-engineered

photonic crystals showed circular dichroism bands in the mid-infrared wavelengths. These cubic chiral srs-networks are

excellent templates for post processing techniques such as electroless deposition, for the development of 3D metamaterials.

It has recently been shown [3] that when scaled to very small sizes, the achiral composite that we recently fabricated using a

polymer photoresist [1] right-handed (RHD) and left-handed (LHD) srs-networks (see Fig. 1 a and b) can lead to a negative

refractive index in a nearly isotropic 3D metamaterial. We present the metallisation of these 3D microstructures using

electroless deposition (see Fig. 1c) and techniques to selectively coat only the polymer srs-network and not the glass

substrate, by using a hydrophobic coating to the substrate. We shall also discuss efforts to fabricate and characterise 3D

microwave metamaterials based on the same srs-network geometry, using 3D printing methods in gypsum.

Fig. 1: a) A achiral composite design consisting of right-handed (RHD) and left-handed (LHD) srs-networks intertwined to

form an achiral structure. b) Scanning electron microscope image of a polymer achiral composite, fabricated using direct

laser writing, the scale bar is 1 μm. c) A RHD srs-network coated with silver via electroless deposition, the scale bar is 1 um.

d) A microwave chiral metamaterial: a large scale srs-network fabricated using a 3D printer using gypsum.

References [1] M. D. Turner, G. E. Schroder-Turk, and M. Gu, “Fabrication and characterization of three-dimensional biomimetic chiral composites,”

Opt. Express 19, 10001-10008 (2011).

[2] M. Saba et al., "Circular Dichroism in Biological Photonic Crystals and Cubic Chiral Nets,", Phys. Rev. Lett. 106, 103902 (2011).[1]

[3] K. Hur, Y. Francescato, V. Giannini, S. A. Maier, R. G. Hennig, and U. Wiesner, “Three‐Dimensionally Isotropic Negative Refractive Index

Materials from Block Copolymer Self‐Assembled Chiral Gyroid Networks,” Angewandte Chemie (In press).

b) c) d) a)

40


41

STUDENT POSTER SESSION

Board Macquarie University

1. Arriola, Alexander Fabrication of thin metallic 1D grating as a constituent of a

refractive index sensor for biomedical applications

2. Cvetojevic, Nick First Astronomical Spectra using an Integrated Photonic

Spectrograph

3. Duan, Yuwen Modelling of Yb-doped waveguide DBR laser fabricated by

femtosecond laser pulses

4. Gross, Simon Femtosecond laser written mid-IR waveguide lasers in zirconium

fluoride glass

5. Helt, Luke Biphoton Engineering with Microring Resonators

6. Meany, Thomas Building quantum simulators in integrated 3D waveguide

circuits

7. Spaleniak, Izabela Exploration of Femtosecond Laser Inscribed Integrated

Photonic Lanterns for Applications in Astronomy

8. Williams, Robert Advanced point-by-point fibre Bragg gratings

Board RMIT

9. Khodasevych, Iryna Pneumatically switchable graded index metamaterial lens for

microwaves

10. Shah, Charan Elastomeric Silicone Substrates for THz Fishnet Metamaterials

Board UTS

11. Kan, Dougal Computational Methods for Modelling Surface Modes of

Photonic Woodpiles

Board University of Sydney

12. Brownless, John Diffraction Engineering with Braided Photonic Crystal

Waveguide Modes

13. Büttner, Thomas Multi-Core, Tapered Fiber for Nonlinear Pulse Reshaping

14. Byrnes, Adam On-chip, Tunable, Narrow-Bandpass Microwave Photonic Filter

Using Stimulated Brillouin Scattering (SBS) 15. Casas-Bedoya, Alvaro W1 photonic crystal liquid waveguide

16. Chen, Parry Fast Simulation of Slab Photonic Crystal Structures using Modal

Methods

17. Collins, Matthew Impact of Cooling on Raman Scattering in an As2S3 Correlated

Photon Pair Source

18. Dekker, Stephen 2.04 μm Light Generation from a Ti:Sapphire Laser Using a

Photonic Crystal Fiber with Low OH loss

19. Fisher, Caitlin Control of dense carbon nanotube arrays via hierarchical

multilayer catalyst

20. Hu, Tomonori Q-switched Holmium fibre laser operating at 2.9 µm

21. Lawrence, Felix

A flexible method to find Bloch modes, complex band

structures, and impedances of two-dimensional photonic

crystals

22. Mahmoodian, Sahand Radiation calculations in photonic crystal cavities using a basis

of bound states

23. Naman, Osama Drawn meta-material for electric response in the mid IR

24. Paquot, Yvan Automatic multi-order dispersion compensation for 1.28

Terabaud transmission

25. Sturmberg, Björn Absorption of Silicon Nanowire Arrays on Silicon and Silica

Substrates

26. Tuniz, Alessandro Fibre Metamaterials with Magnetic Resonances in the Terahertz

Range

42

STUDENT POSTER SESSION

Board ANU Nonlinear Physics Centre

27. Hannam, Kirsty Tunable Nonlinear Response of Split Ring Resonators

28. Kruk, Sergey Optimization of Multi-layer Fishnet Optical Metamaterials

29. Liu, Mingkai Optical activity and coupling in twisted dimer metamaterials

30. Liu, Wei Polarization independent Fano resonances in arrays of core-

shell nanospheres

31. Solntsev, Alexander Control of Photon-Pair Generation and Spatial Quantum State

in Waveguide Arrays with Cubic Nonlinearity

32. Sun, Yue Optical forces between longitudinally shifted nano‐beam

cavities

Board ANU Laser Physics Centre

33. Su, Xueqiong Optical annealing of thermally evaporated Ge-As-Se thin films

34. Wang, Ting EXAFS study of the local order in Ge-As-Se glasses

35. Wei, Wenhou Thermal characterization of Ge-Sb-Se chalcogenide glasses

36. Yan, Kunlun Photoluminescence of erbium doped stable Ge-Ga-Se

chalcogenide glasses

Board Swinburne University

37. Cumming, Ben Nonlinear chalcogenide gyroids fabricated with direct laser

writing

38. Gan, Zongsong Spontaneous emission enhancement with defects in a three

dimensional pseudo-gap photonic crystal

39. Gan, Zongsong Theoretical modeling of doughnut beam based superresolution

photoinhibition-induced nanolithography

40. Gan, Zongsong Nanometer localization of single semiconductor quantum dots

inside a three-dimensional photonic crystals

41. He, Zhengguang (John) Spontaneous emission control with three-dimensional hybrid

photonic crystals

42. Hossain, Md Muntasir Ultrahigh nonlinearity in nanoshell plasmonic waveguides

43. Lin, Han Broadband nanofocusing of light in dielectric chalcogenide

glass nanogratings

44. Lin, Han Generate multifocal diffraction-limited non-Airy pattern arrays

for large area parallel fabrication of novel metamaterials

45. Turner, Mark

Achieving true cubic symmetry in three-dimensional

biomimetic chiral photonic microstructures via galvo-mirror

dithering

43

STUDENT POSTER ABSTRACTS

Fabrication of thin metallic 1D grating as a constituent of a refractive index sensor for

biomedical applications

A. Arriola (1,2), A. Rodriguez (3), T. Tavera (2), N. Perez (2), M. Withford (1), A. Fuerbach (1), S.

M. Olaizola (2)

1 Centre for Ultrahigh bandwidth Devices for Optical Systems

Department of Physics and Astronomy, Macquarie University

2 CEIT and Tecnun (University of Navarra, Spain)

3 CIC Microgune, Microsensors Unit


Gratings were fabricated on a thin Au layer using laser interference lithography technique (LIL)[1] and a frequency

triplicated Nd:YAG nanosecond laser. The thin Au layer was deposited on a bulk borosilicate glass. Fabricated gratings

were designed with a 770nm period and were characterized in terms of their period, depth and plasmonic resonance.

In this paper we report on the fabrication of thin metallic 1D layer gratings as a constituent of a refractive index

sensor (See Fig. 1) for biomedical applications [2].

The fabrication process is as follows: thin metallic layer deposition by magnetron sputtering, spinning of the

photoresist, photoresist exposure using the laser interference technique to get the periodic pattern on the

photoresist and Ar ion bombardment in order to transfer the pattern to the thin Au layer.

Gratings were characterized in terms of their geometries (See Fig. 2) and plasmonic resonance, and plasmon

coupling effects have been identified for orders 1, -1 and -2.

Fig. 1: Schematic of an integrated refractive index sensor Fig. 2: AFM micrograph of the 1D gratings

References 1 A. Rodriguez, M. Echeverría, M. Ellman, N. Perez, Y.K. Verevkin, C.S. Peng, T. Berthou, Z. Wang, I. Ayerdi, J. Savall, S. M.

Olaizola, “Laser interference lithography for nanoscale structuring of materials: From laboratory to industry”

Microelectronic Engineering, volume 86, issue 4-6, year 2009, pp. 937 – 940

2 A. Arriola, M. J. Withford, S. M. Olaizola, A. Fuerbach, “Inscribed waveguides in borosilicate glass using ultrashort laser pulses for

biomedical applications”, CUDOS Workshop Proceedings (2011).


44

First Astronomical Spectra using an Integrated Photonic Spectrograph

Nick Cvetojevic, Nemanja Jovanovic, Chris Betters, Jon Lawrence, Simon Ellis, Gordon Robertson,

Michael Withford and Joss Bland-Hawthorn



Phone: 9850 8951


We present results from the first ever successful, on-telescope test of a miniature photonic spectrograph for astronomy, by

attaining a spectrum form a stellar source. Furthermore, we successfully obtain multiple spectra simultaneously from a

single device, with multiple fibre inputs, demonstrating the feasibility of using the integrated photonic spectrograph for

multi-object spectroscopy for the first time.

Summary: The Integrated Photonic Spectrograph (IPS) is a complete spectrograph on a single silica photonic

chip, which can potentially revolutionize astronomical instrumentation by removing the need for expensive and

large optical components traditionally used in spectrograph construction. The IPS is small, light weight, has no

moving parts, and is relatively inexpensive compared to conventional spectrographs used in astronomy. In fact,

the IPS can provide these benefits without sacrificing properties required for an astronomical spectrograph.

We interfaced the IPS with the 3.9 m Anglo-Australian Telescope at Siding Spring Observatory in Australia, by

collecting the light at the focal plane of the telescope with a multimode fibre, which must be used as direct

focusing into a single-mode fibre on a telescope of this size is highly impractical due to atmospheric turbulence.

Because the performance of the IPS severely degrades if multimode fibres are injected directly into the chip, we

used a transitional multi-fibre taper called a photonic lantern, which converted the multimode signal from the

telescope into multiple single modes (twelve in our case) which were injected into the chip.

Fig. 1: Spectrum taken by the IPS of star V*01 Pi Gru. Carbon monoxide absorption band heads are visible and agree with

predicted values (dotted vertical black lines). Possible detection of elemental absorption lines such as Calcium and

Aluminium (dotted blue & red). This result is the first measurement of spectral features of an astronomic source using a

photonic spectrograph.

Figure 1 above presents the first ever stellar spectrum taken using a photonic spectrograph on a major research

telescope. Testing on telescope commenced on the 19th May 2011, where we successfully recorded spectra from

a number of stars, including Antares (α Sco), the brightest star in the constellation of Scorpio, and V*01 Pi Gru an

old dying star with spectral features within the wavelength window of our device.


45

Modelling of Yb-doped waveguide DBR laser fabricated by femtosecond laser pulses

Yuwen Duan, M.J. Steel, Nemanja Jovanovic, Graham Marshall and Michael Withford

MQ Photonics Research Centre

Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS)

Department of Physics & Astronomy, Macquarie University, NSW 2109, Australia


A model analysing the propagation of pump and signal power in Yb-doped waveguide DBR laser fabricated by femtosecond

laser pulses is presented. The model is based on rate equations and gives emphasis to transverse space integrals. Numerical

results show that about 20% output power is absorbed by the doped glass around the waveguide.

Femtosecond laser (fs-laser) writing technique is a promising technique for fabricating monolithic waveguide

lasers [1]. Modelling of the waveguide laser fabricated by such technique is required in order to predict the laser

behavior and yield improved laser design. In contrast to fibre lasers, waveguide lasers are often fabricated in

homogenously doped glasses resulting in a doped ‘cladding’ around waveguides. Instead of using an effective

overlap parameter [2] widely adopted in fiber laser models, our model pays more attention on transverse space

integrals. Modeling based on rate equations reveals that the output power is slightly reduced because of the

doped glass around the waveguide.

The DBR waveguide laser consisted of a waveguide in whole doped glass with Bragg reflectors on both sides.

Rate equations at steady state describe the effects of absorption, stimulated emission and spontaneous emission

with the forward and backward propagating pump and signal beams as well as the rare earth ion population in

the upper energy level [3]. In order to identify the contribution effect of the doped ‘cladding’ region around the

waveguide to laser performance, a waveguide DBR laser structure with undoped ‘cladding’ was assumed for

comparison. Fig.1 (a) and (b) illustrates the variation of the pump and signal powers along the waveguide of the

Yb-doped laser when the pump power is injected at z=0. For the input power of 200 mW, it takes about 1.5 cm

length for the input power to be completely absorbed in whole doped glass while 4.5 cm length in the

waveguide with non-doped ‘cladding’. At the same time the highest output power is 100 mW and 140 mW

respectively. In Fig.1 we present the output power as a function of the pump power with the length of 4.5 cm

and 1.6 cm respectively. The lasing threshold is 50 mW and 90 mW respectively for the two structures. The slope

efficiency is high which almost reaches the theoretical maximum conversion efficiency. However it should be

noted that the scattering losses have not been taken into account.

(a) (b) (c)

Fig.1 Power distribution of the pump and laser field along the waveguide (a) in fully doped glass (b) in non-doped glass

(c)Output power versus input pump power for waveguide laser (L=4.5cm) in fully doped glass and non-doped glass (L=2cm)

References [1] Ams, M., et al., “Monolithic 100 mW Yb waveguide laser fabricated using the femtosecond-laser direct-write technique,” Opt. Lett. 34,

247-249 (2009).

[2] Rebolledo, M.A. and S. Jarabo, “Erbium-doped silica fiber modeling with overlapping factors,” Appl. Opt. 33, 5585-5593 (1994).

[3] Giles, C.R. and E. Desurvire, “Modeling erbium-doped fiber amplifiers.” Lightwave Technology, Journal of 9, 271-283 (1991).

[4] Henry, C., “Theory of spontaneous emission noise in open resonators and its application to lasers and optical amplifiers,” Lightwave

Technology, Journal of 4, 288-297 (1986).


46

Femtosecond laser written mid-IR waveguide lasers in zirconium fluoride glass

S. Gross1, D. G. Lancaster2, H. Ebendorff-Heidepriem2, T. M. Monro2, M. J. Withford1 and A.

Fuerbach1

1. Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS), MQ Photonics Research

Centre, Department of Physics and Astronomy, Macquarie University, NSW, 2109, Australia

2. Institute for Photonics and Advanced Sensing (IPAS), School of Chemistry and Physics, The

University of Adelaide, SA, 5005, Australia


We report on thulium and holmium/thulium waveguide lasers emitting in the 2 µm spectral region. The waveguides lasers

are fabricated by the femtosecond laser direct-write technique in zirconium fluoride glass utilizing a depressed cladding

waveguide structure. The lasers emit at 1880 and 2050 nm respectively with internal slope efficiencies of up to 51%, output

powers as high as 245 mW and lasing thresholds as low as 17 mW.

The 2 µm spectral region is of interest for many applications like trace gas spectroscopy, laser ranging, coherent

LIDAR and testing of infrared countermeasure systems, which demand robust and cheap laser sources.

However their ready availability is limited.

Many fibre and solid-state thulium and holmium lasers have been reported [1]. However waveguide lasers have

got several advantages. Waveguide chips can be highly integrated into a robust package without the need for

any bulk optics. They offer diffraction limited beam quality and they can be of very low lasing threshold thus

enabling pumping by low-cost diode lasers.

The waveguides are fabricated in rare-earth doped zirconium fluoride glass (ZBLAN) by focusing a

femtosecond oscillator into the bulk material. Heat diffusion followed by heat accumulation due to the high

pulse repetition rate of the writing laser results in structures of nearly circular cross section with a reduced

refractive index (Δn ≈ -1.610-3). A waveguide is formed by arranging 24 modifications in 2 rings around an

unmodified core (see figure 1 (a)) [2].

For the experiments 2.0 mol.% thulium doped glass and 1.96 mol.% thulium doped glass, co-doped with

0.22 mol.% holmium was used. Both waveguide chips were pumped by a Ti:sapphire laser with a wavelength of

790 nm to utilise the efficient cross-relaxation process between two neighbouring thulium ions. The resonator

was formed by butting up external mirrors to the end faces of the chips.

a) b) c)

Fig. 1: (a) End on optical microscope image of a waveguide, (b) performance of the thulium waveguide laser, (c) performance

of the holmium/thulium waveguide laser.

The thulium doped glass shows the highest internal slope efficiency of 51%. It emits at 1880 nm with a total

output power of 245 mW and a threshold of 17 mW. The holmium laser reaches a slope efficiency of 20% while

lasing at 2050 nm. Its maximum output power is 76 mW.

[1] I. T. Sorokina, and K. L. Vodopyanov, “Solid-state mid-infrared laser sources,” Springer, (2003)

[2] D. G. Lancaster, S. Gross, H. Ebendorff-Heidepriem, K. Kuan, T. M. Monro, M. Ams, A. Fuerbach, and M. J. Withford, "Fifty percent

internal slope efficiency femtosecond direct-written Tm3+:ZBLAN waveguide laser," Opt. Lett. 36, 1587-1589 (2011)

0 100 200 300 400 500 6000

50

100

150

200

250

300

= 51%

19

00

nm

Ou

tpu

t P

ow

er

(mW

)

Absorbed 790 nm Pump Power (mW)

R=77% OC

1860 1870 1880 1890 1900

Wavelength (nm)

Dete

cto

r P

ow

er

(a.u

.)

0 100 200 300 400 5000

20

40

60

80

100

= 15%

R=95% OC

R=98% OC

20

50

nm

Ou

tput

Po

we

r (m

W)

Absorbed 790 nm Pump Power (mW)

= 20%

2040 2050 2060

Dete

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(a.u

.)

Wavelength (nm)


47

Biphoton Engineering with Microring Resonators

L.G. Helt and J.E. Sipe

Department of Physics and Institute for Optical Sciences,

University of Toronto, 60 St. George St., Toronto, Ontario M5S 1A7, Canada


We consider spontaneous parametric downconversion in both microring resonators side-coupled to straight waveguides and

straight waveguides themselves. We demonstrate that the shape of the resulting biphoton probability density depends

strongly on dispersion for the straight waveguide, and on coupling between the ring and the waveguide for the resonator.

This second fact presents a novel way to realize the efficient generation of uncorrelated photons on a chip.

In addition to predicting the rate of pair generation, it is important to understand the range of possible

quantum correlated states of photon pairs generated in various artificially structured media. Anti-correlated

pairs find use in QKD, while uncorrelated pairs are useful as heralded single photon sources for use in quantum

computing [1] or fundamental tests of quantum mechanics [2]. Thus, it is useful to examine the general form of

the biphoton probability density,

, associated with photons generated in each a channel

waveguide, C, and a microring resonator side-coupled to a channel waveguide, R, as well as the parameters that

need to be adjusted in order to achieve a particular shape of the biphoton probability density in each structure.

We work in the undepleted pump approximation and the limit of no noise or loss in analyzing photon pair

generation due to a spontaneous parametric downconversion process in both a channel waveguide [3], and

microring resonator [4]. Under these assumptions the resulting biphoton probability density in each case takes

the same general form: a benign function of the generated frequencies, , times a pump waveform

that is a function of the sum of the generated frequencies, , times another function of the generated

frequencies, . For photons generated in a channel, the “other” function is a phase matching squared

sinc function that depends on the group velocities, , of the three fields involved

whereas for photons generated in a microring, where phase matching essentially occurs for free if resonances

satisfying energy conservation can be found, the function is a product of three Lorentzian functions with

linewidths that, respectively, depend on the strength of the coupling of the ring to itself at the point of coupling

with the side-coupled channel, or field self-coupling coefficient, , of each of the three fields involved

where is the length of the structure.

Thus, dispersion engineering the waveguide to ensure that the group velocity of the pump lies between the

group velocities of the generated photons can result in a factorable biphoton probability density and therefore

uncorrelated photons [5]. In fact, for appropriate group velocity values, the biphton probability density can be

made to point along any direction in the plane. For generation in a microring resonator, the larger self-

coupling of a given mode at higher frequencies tends to “squish” the biphoton probability density in the

direction perpendicular to . However, pumping at a higher order mode can reduce the self-

coupling strength such that the product of Lorentzians is factorable resulting in a Schmidt Number [6] of exactly

1.

References 1. E. Knill, R. Laflamme, and G.J. Milburn, “A scheme for efficient quantum computation with linear optics,” Nature 409, 46 (2001).

2. C.K. Hong, Z.Y. Ou, and L. Mandel, “Measurement of subpicosecond time intervals between two photons by interference,” Phys. Rev. Lett. 54,

2044 (1987).

3. Z. Yang, M. Liscidini, and J.E. Sipe, “Spontaneous parametric down-conversion in waveguides: A backward Heisenberg picture approach,” Phys.

Rev. A 77, 033808 (2008).

4. Z. Yang and J.E. Sipe, “Generating entangled photons via enhanced spontaneous parametric downconversion in AlGaAs microring resonators,”

Opt. Lett. 32, 3296 (2007).

5. J Svolzilik, M. Hendrych, A.S. Helmy, and J.P. Torres, “Generation of paired photons in a quantum separable state in Bragg reflection

waveguides,” Opt. Express 19, 3115 (2011).

6. C.K. Law and J.H. Eberly, “Analysis and interpretation of high transverse entanglement in optical parametric downconversion,” Phys. Rev. Lett.

92, 127903 (2004).


48

Building quantum simulators in integrated 3D waveguide circuits

Thomas D. Meany, Graham D. Marshall, M. J. Steel, and Michael Withford

Centre for Ultrahigh bandwidth Devices for Optical Systems,

MQ Photonics Research Centre, Department of Physics and Astronomy,

Macquarie University, North Ryde, NSW, 2109

Phone: +61-2-9850-8938


The building blocks required to build an effective integrated optic quantum simulator have been studied. This includes

polarization dependent coupling and non nearest neighbour coupling in evanescently coupled 3D waveguide arrays. The

direct application of this knowledge in quantum random walks and biological simulations is currently underway.

The ultimate goal of a quantum computer, promising exponential speed up in processing power, is at best

decades away. However an enormous amount can be learned about inherently quantum phenomena by using

quantum simulation [1]. It has been shown that it is possible to emulate the unitary evolution of a system’s

Hamiltonian physically rather than use traditional computational methods to simulate the process [2]. Laser

written waveguides have been used to produce initial embodiments [3] and they offer another degree of

freedom in attempting to emulate a system’s Hamiltonian owing to its inherently 3 dimensional capability.

When developing a systems Hamiltonian in integrated optics it is vital to understand the physical processes

occurring classically as well as performing a quantum characterisation. In 3 dimensions the uniformity of laser

written waveguides is often incorrectly assumed and this has led to us to a study of polarisation dependence of

the evanescent coupling between waveguides. Developing symmetric waveguides and understanding the

contribution of asymmetry both to coupling in different directions and polarisations has been an early part of

our work. In addition, the effect of non nearest neighbour coupling (NNNC) on waveguide arrays has been

studied. This is particularly important for laser written waveguides due to the low index contrast regime and

long propagation distances. Early work incorporating waveguide arrays of varying orientations (see Fig.1) has

shown that indeed non nearest neighbour coupling is a significant effect. It has led us to incorporate this effect

into computational simulations of system evolution (Fig.2).

Fig.1: Non nearest neighbour coupling in waveguide array

showing (top) a linear array and (bottom) the increased effect

of NNNC in curved arrays.

Fig.2: Theoretical coupling matrices for a (top) 2 and

(bottom) 3-dimensional waveguide array.

This progress forms the foundations for the emulation of quantum systems in laser written waveguide arrays. In

particular for performing quantum random walks and more elaborate biological simulations of systems of

interest such as the light-harvesting complexes in bacteria and plants.

References [1] R. Feynman, et al. “Simulating physics with computers” Int. J. Theor. Phys. 21 pp.467–4887 (1982)

[2] A. Peruzzo, et al. “Quantum walks of correlated photons” Science 329 (5998) pp.1500–1503 (2010)

[3] J. O. Owens, et al. “Two-photon quantum walks in an elliptical direct-write waveguide array,” New J. Phys. 13( 7) 075003 (2011)


49

Figure 1. 2D (top) and 3D (bottom) sketches of a MM-to-

SM (left) and SM-to-SM (right) integrated photonic

lantern. Separation of the SM waveguides is 37.5 μm and 6

μm at the SM and MM ends of the device respectively

(note that the image is not to scale).

Exploration of Femtosecond Laser Inscribed Integrated Photonic Lanterns

for Applications in Astronomy

Izabela Spaleniak1,2, Nemanja Jovanovic1,2,4, Simon Gross1,3, Michael Ireland1,2,4, Jon Lawrence1,2,4,

and Michael Withford1,2,3 1MQ Photonics Research Centre, Department of Physics and Astronomy, Macquarie University

2Centre for Astronomy, Astrophysics and Astrophotonics, Macquarie University 3Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS)

4Australian Astronomical Observatory (AAO)

Phone: +61 2 9850 8978


We are using a femtosecond laser to inscribe a series of integrated photonic lanterns that have a range of refractive index

contrasts and geometry parameters in order to determine the ideal format for optimising the single-mode to multimode

transition efficiency for future work in the visible.

Developments in photonic technologies offer the potential to revolutionise astronomical spectrograph

capabilities [1-2], with integrated photonics showing great promise. Photonic spectrograph requires a single-

mode (diffraction-limited) light input. This can be provided either by applying adaptive optics correction or

converting a multimode (MM) fibre core into series of SM fibre cores using a device called a photonic lantern [3].

The ‘classical’ method of making photonic lanterns is based on optical fibres [4]. However we propose to

fabricate photonic lanterns using the direct laser writing technique to inscribe the waveguides within the glass

sample with ultrafast laser pulses. Its main advantage is the integration of the numerous SM ports which makes

it practically scalable.

We have fabricated set of photonic lanterns with 7 SM waveguides (Fig. 1), which were design to work in IR. By

changing the laser pulse energy and translation speed we were changing the refractive index modification.

Based on out transmission measurements for different

waveguides the throughput ranges from 20-40%, with

an average of 30%. This is just the initial result and

there is a large parameter space which we will explore

in order to optimise the device. We saw that the

throughput can vary with the depth of inscription.

We are continuing these studies, including

comprehensive modelling in BeamPROP (RSOFT), and

anticipate manufacturing lanterns with much higher-

throughput and higher mode-count guides over the

coming months. The ultimate goal will be to create

high-efficient photonic lantern working in the visible.

References: Bland-Hawthorn, J., “Astrophophotonics: A new generation of astronomical instruments in Optical Fiber Communication (OFC)”, collocated

National Fiber Optic Engineers Conference, 2010 Conference on (OFC/NFOEC), (2010).

N. Cvetojevic, et al., "Characterization and on-sky demonstration of an integrated photonic spectrograph for astronomy," Opt. Express, 17(21): p. 18643-18650, (2009).

S.G Leon-Saval, A. Argyros, and J. Bland-Hawthorn, "Photonic lanterns: a study of light propagation in multimode to single-mode converters," Opt. Express, 18(8): p. 8430-8439, (2010).

D. Noordegraaf, et al., "Efficient multi-mode to single-mode coupling in a photonic lantern," Opt. Express, 17(3): p. 1988-1994, (2009).


50

Advanced point-by-point fibre Bragg gratings

Robert J. Williams, Graham D. Marshall, M. J. Steel, and Michael J. Withford


MQ Photonics Research Centre, Macquarie University

Phone: +61 2 9850 8929


Point-by-point inscription of fibre Bragg gratings using femtosecond lasers is a highly flexible technique, attracting

increasing attention for fibre laser and fibre sensing systems. Here we present our recent work in fabricating the first

complex and apodized gratings using this technique, and highlight our new insights into the fundamental characteristics of

these gratings. Some new applications for these gratings in fibre laser systems will also be presented.

Fiber-Bragg gratings (FBGs) inscribed with a femtosecond laser [1] have proven advantages for a variety of

applications because they exhibit excellent stability at elevated temperatures and under intense optical

pumping, and can be directly inscribed into virtually any transparent fiber material. The point-by-point (PbP)

technique for fabricating FBGs with a femtosecond laser is uniquely flexible as it produces gratings which

consist of discrete refractive index modifications with sub- to few-micron dimensions, yet with high refractive

index contrast. These highly-localized modifications provide the flexibility to control the interaction between the

grating and the light in the fibre core: varying the lateral position of each of the modifications enables tailoring

of the local coupling strength; while variations in the longitudinal position of the modifications can be used to

control the phase and frequency response of the grating.

Using these degrees of freedom for the first time, we demonstrated a suite of complex PbP FBGs, including

phase-shifted, sampled, superstructured, chirped and apodized FBGs [2,3]. This dramatic increase in the

capabilities of PbP FBGs paves the way for a multitude of new applications of these gratings, particularly for

fibre laser and fibre sensing applications. Additionally, these new complex gratings are providing new insights

into the fundamental properties of PbP FBGs due to their unique sensitivity to the refractive index profile of the

modifications.

In this work we present some of our recent results in apodized PbP FBGs and demonstrate how these gratings

have provided new insights into the refractive index profile of the PbP modifications. We also discuss an

application of these gratings for building short-pulsed fibre lasers.

Fig. 1: (Left) Illustration of Gaussian apodization technique. (Right) Gaussian-apodized FBG spectrum compared to

simulated uniform FBG spectrum.

1. A. Martinez, et al., "Direct writing of fibre Bragg gratings by femtosecond laser," Electron. Lett. 40, 1170-1172 (2004). 2. G. D. Marshall, et al., "Point-by-point written fiber-Bragg gratings and their application in complex grating designs," Opt. Express 18,

19844-19859 (2010). 3. R. J. Williams, et al., "Point-by-point inscription of apodized fiber Bragg gratings," Opt. Lett. 36, 2988-2990 (2011).

0 3 6 9 12 150.0

0.1

0.2

0.3

0.4

(

mm

-1)

Position along grating (mm)

1522.5 1523.0 1523.5

-14

-12

-10

-8

-6

-4

-2

0

Experiment

Uniform

(Simulation)

Ref

lect

ion

(d

B)

Wavelength (nm)


51

Pneumatically switchable graded index metamaterial lens for microwaves

Iryna Khodasevych1, Ilya V. Shadrivov2, David A. Powell2, Wayne S.T. Rowe1, and Arnan Mitchell1

Centre for Ultrahigh bandwidth Devices for Optical Systems 1School of Electrical and Computer Engineering, RMIT University

2Nonlinear Physics Centre, School of Physics and Engineering, Australian National University

Phone: 61399252457 Email: [email protected]

We demonstrate pneumatic switching of graded index metamaterial lens operating at GHz frequencies. Graded index is

achieved by using split ring resonators of different widths. Switching between focusing and not focusing states is achieved

by shortening the gap in split ring resonators with pneumatically actuated metal patches. This leads to disappearance of

resonant response and evening of phase difference between the elements on the edges and in the center of the lens.

Graded index lenses have uniform thickness and are considerably thinner than traditional curved lenses.

However requirement to have varying refractive index within the material introduces fabrication difficulties.

Metamaterials refractive indices can be varied in much greater extent than possible with natural materials by

simply changing the geometry of constituting unit cells. This can allow reducing thickness of the lens even

further. Metamaterial graded index lenses have been reported in [1, 2]. Exploiting electric rather than magnetic

resonance requires split ring resonators to be oriented perpendicular to incident radiation and allows planar

ultrathin lens design, which is easy to fabricate. The proposed lens is switched pneumatically between focusing

and not focusing states.

The required phase distribution along the length of the lens can be calculated from the following expression:

, where f is the focal length of the lens, λ is the incident wavelength, and ϕ is the required phase at the distance x from the center of the lens. The phase profile is approximated with

staircase, each step corresponding to unit cell size. Phase shift through each unit cell is controlled by the width of

split ring resonator. Unit cell is 12x12 mm (Fig. 1(a)) and consists of 0.5 mm copper-clad duroid layer with split

ring resonator and additional layer of flexible substrate 0.1 mm thick with metal patch facing the split ring. Lens

has 13 unit cells of total length 15.6cm. The layers are sealed around the edges of the lens and connected to

vacuum pump for pneumatic switching. In switch open actuation state layer with the patches is at 1mm from

the spit rings and does not interfere with resonant response. In switch closed state the air is pumped out and

metal patch comes in contact with the split ring and shortens it, eliminating the resonant response and

corresponding phase shift.

The lens is designed for operation at 10GHz. Fig. 1(b, c) shows simulated intensity distributions where

focusing can be seen at 11cm from the lens in switch open state and no focusing is seen in switch closed state.

Because of small size of the lens some diffraction is also present.

Fig. 1: (a) Unit cell of the lens. Intensity distributions and lens profiles in switch open (b, d) and switch closed (c, e) states.

References 1. T. Driscoll, D. N. Basov, A. F. Starr, D. Schurig, D. R. Smith, “Free-space microwave focusing by a negative-index gradient lens,” Applied

Physics Letters, Vol 88, 081101, (2006).

2. R. B. Greegor, C. G. Parazzoli, J. A. Nielsen, M. A. Thompson, M. H. Tanielian , D. R. Smith, “Simulation and testing of a graded negative

index of refraction lens,” Applied Physics Letters, Vol 87, 091114, (2005).


52

Elastomeric Silicone Substrates for THz Fishnet Metamaterials

C. M. Shah, I. E. Khodasevych, S. Sriram, M. Bhaskaran, W. S. T. Rowe, and A. Mitchell




The electromagnetic properties of polydimethylsiloxane (PDMS) are characterized at terahertz frequencies, with PDMS

used to realize free-standing, flexible fishnet metamaterials.

Increasing interest for terahertz (THz) metamaterial structures and their diverse applications have given birth to

metamaterials fabricated on the flexible substrate [1]. This work presents a technique to fabricate large area,

micro-scale, THz fishnet structures on a flexible elastomeric substrate. Electromagnetic modeling was used to

determine the geometry of the fishnets for resonances at ~2 THz. These structures were fabricated by a multi-

layer photolithography process using PDMS and gold-chromium multi-layers on a silicon substrate. The final

multi-layer fishnet was peeled off the silicon substrate which served as a support for micro-fabrication.

Fig. 1. (a) Photograph of elastomeric fishnet structure. (b) Micrograph showing 9 fishnet unit cells with a 3 μm misalignment.

Fig. 2. Simulated and measured THz response of PDMS-based fishnet structures. Good agreement can be observed in

transmission intensity and peak position, including the expected stop band splitting due to the 3 μm misalignment.

Fabricated fishnet sections were tested in a 1.0-4.0 THz bandwidth system in a transmission arrangement with

nitrogen purge. Sharp resonance at ~2.1 THz corresponding to the original simulation was obtained. Additional

peaks were observed, the origins of which have been analyzed by additional simulations and considering

misalignment between the two fishnet layers.

References 1. H. Tao, A. C. Strikwerda, K. Fan, C. M. Bingham, W. J. Padilla, X. Zhang, R. D. Averitt, “Terahertz metamaterials on free-

standing highly-flexible polyimide substrates,” Journal of Physics D: Applied Physics 41, 232004, (2008).


53


54

Fig. 2: Propagation through the PCW array

system described in Fig1 inset. At d/λ=0.3494

(left) and d/λ=0.3444 (right) .

Fig. 1: Dispersion relations for the PCW arrays shown in inset.

Background index n=3, hole index n=1, waveguide index n=1.5.

Diffraction Engineering with Braided Photonic Crystal Waveguide Modes

J. Scott Brownless, Felix J. Lawrence, Kokou B. Dossou, Sahand Mahmoodian,

Lindsay C. Botten, and C. Martijn de Sterke

CUDOS, University of Sydney & University of Technology Sydney

Phone: 9036 5187


We consider discrete diffraction in hexagonal lattice photonic crystal waveguide arrays. We report strong frequency dependence

of the (discrete) diffraction coefficient. Although interesting in its own right, this result has consequences for the discrete spatial

solitons.

Discrete diffraction is the broadening of light over distance in a

coupled waveguide array. Though seemingly very similar to

conventional diffraction in continuous media, Eisenberg et al. have

shown that the effective diffraction coefficient varies and can even

change sign, depending on the relative phase of the light in the

different waveguides [1].

The discrete diffraction coefficient also depends on the coupling

strength between neighbouring waveguides. Using a nearest

neighbour approximation, this coupling coefficient was found to

depend on the deifference between of the odd and even coupled

waveguide modes: if the fundamental mode is even,

the coupling is positive and vice versa.

Locatelli et al. used de Sterke et al.’s work [2] on

square lattice PCWs to show that the sign of the

diffraction coefficient can be reversed [3]. They simulated two PCW arrays with opposite diffraction coefficient

joined over an interface and showed that the effects of diffraction are reversed as light passes over into the second

PCW array.

We showed previously that coupled PCWs in hexagonal lattices support a pair of coupled waveguide modes

that are braided, intertwining around the dispersion relation of the single waveguide mode [4]. We utilise this to

create a PCW array with strongly frequency-dependent diffraction. We simulate the propagation of light through

this array, interfaced with an array where the coupling coefficient is essentially constant over the same frequency

range (Fig. 1).

This allows us to tune the diffraction in the PCW array system such that

the sign of the diffraction is unchanged across the interface (Fig. 2 left), to

reversing the diffraction (Fig. 2 right), and anything in between solely by

changing the frequency. Since this effect is linear, by adding a nonlinearity we

predict the ability tune in and out of discrete special solitons by changing the

frequency.

[1] HS Eisenberg, Y. Silberberg, R. Morandotti, and JS Aitchison. “Diffraction management.” Physical

Review Letters, 85, 1863-1866, (2000).

[2] C.M. de Sterke, LC Botten, AA Asatryan, TP White, and RC McPhedran. “Modes of coupled photonic

crystal waveguides.” Optics letters, 29 1384-1386, (2004).

[3] A. Locatelli, M. Conforti, D. Modotto, and C. De Angelis. Diffraction engineering in arrays of photonic

crystal waveguides.” Optics letters, 30, 2894-2896, (2005).

[4] J.S. Brownless, S. Mahmoodian, K.B. Dossou, F.J. Lawrence, L.C. Botten, and

C.M. de Sterke. “Coupled waveguide modes in hexagonal photonic crystals.” Optics

Express, 18, 25346-25360, (2010).


55

Multi-Core, Tapered Fiber for Nonlinear Pulse Reshaping

Thomas Büttner1, Darren D. Hudson1, Eric C. Mägi1, Alvaro Casas Bedoya1, Thierry Taunay2,

and Benjamin J. Eggleton1 1Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS), School of Physics,

University of Sydney, NSW 2006, Australia

2OFS Laboratories, 600 Mountain Avenue, Murray Hill, NJ 07974-0636, USA

Phone: 0468340600

Email: ([email protected])

We present a new method to create a coupled waveguide array via tapering multi-core telecommunications fiber. This device

exhibits the novel physics associated with coupled waveguide arrays: discrete self-focusing and nonlinear pulse chopping.

Systems of coupled waveguide arrays have demonstrated a host of novel physical phenomena such as discrete

spatial solitons and nonlinear pulse reshaping [1], which are based on the nonlinear index of refraction of the

medium. While the early demonstrations of these phenomena relied on coupled waveguide arrays in AlGaAs-

based planar platforms, more recent work [2] has used optical fibers with multiple-cores.

We present a new method to create coupled waveguide arrays with engineerable interaction strength between

the waveguides by tapering a 7-core telecommunications fiber using a taper rig (Fig. 1(a)). During the tapering,

light from an ASE-source is sent through the central core and an InGaAs camera is used to monitor the output

distribution. Initially, no coupling can be observed due to the large core separation. As the fiber is tapered to

smaller dimensions, light starts to evanescently couple to the other cores. The tapering process can be stopped at

any time and, therefore, a device created with any amount of coupling between the waveguides.

Non-linear coupling effects of a device (taper waist length 4cm, diameter 119 m), built using this method, were

explored by coupling high peak power pulses into one of the cores (Fig. 1 (b)). Fig. 1 (c) shows the non-linear

coupling observed with an InGaAs camera at the output facet for two different peak powers: up to 25kW most

light is coupled to the other cores; at higher powers, however, the light stays confined in the launch core due to

nonlinear self-focusing. Measuring the autocorrelations of input and output pulses for the launch core (Fig. 1

(d)), pulse chopping of 28% could be observed for high peak powers as the low intensity wings of the pulses are

evanescently coupled to the other cores, whereas the high intensity central part of the pulses are self-focused in

the launch core.

Fig. 1: (a) Layout for construction and monitoring the coupled waveguide devices. (b) Experimental setup for testing non-

linear properties of the tapered fibers. VA variable attenuator, MO microscope objective, FM flip mirror, MCF multi-core

fiber, OPA optical parametric amplifier. (c) Coupling between the cores observed with an InGaAs camera for two different

peak powers for the setup shown in (b). (d) Autocorrelation traces for input and output pulses for the launch core.

References [1] D. D. Hudson, K. Shish, T. R. Schibli, J. N. Kutz, D. N. Christodoulides, R. Morandotti, and S. T. Cundiff, "Nonlinear femtosecond pulse

reshaping in waveguide arrays," Opt. Lett. 33, 1440-1442 (2008).

[2] S. Minardi, F. Eilenberger, Y. V. Kartashov, A. Szameit, U. Röpke, J. Kobelke, K. Schuster, H. Bartelt, S. Nolte, L. Torner, F. Lederer, A.

Tünnermann, and T. Pertsch,”Three-Dimensional Light Bullets in Arrays of Waveguides,” Phys. Rev. Lett. 105, 263901 (2010).


56

On-chip, Tunable, Narrow-Bandpass Microwave Photonic Filter Using Stimulated

Brillouin Scattering (SBS)

Adam Byrnes(1), Ravi Pant(1), Christopher G. Poulton(2), Enbang Li(1), Duk-Yong Choi(3), Steve

Madden(3), Barry Luther-Davies(3), and Benjamin J. Eggleton(1)

Centre for Ultrahigh bandwidth Devices for Optical Systems (1)University of Sydney, (2)University of Technology Sydney, (3)Australian National University


We report the first demonstration of a narrow-bandpass (~20MHz), on-chip, tunable, photonic filter for RF signals, using

SBS in a chalcogenide waveguide. Extinction ratios of over 20dB, a frequency range of 2-12GHz and a Q-factor of 600 were

realized.

Performing filtering of RF signals in the optical domain has

a number of advantages, including wide tunability and

natural immunity to electromagnetic interference [1].

Recently, several approaches for implementing these

microwave photonic filters (MWPFs) have been

demonstrated [1,2]. Realization on a chip-scale device is

considered essential for all-optical integration, and a recent

scheme using microring resonators realized a filter

bandwidth ~ GHz [3]. To date however, none of these chip-

scale demonstrations have achieved narrow-bandpass

filtering.

Here, we report the first demonstration of an on-chip,

tunable, narrow-bandpass microwave photonic filter, using

Stimulated Brillouin Scattering (SBS) in a 15cm long

chalcogenide (As2S3) rib snake waveguide (see Fig 1.A/B)

fabricated on a 7cm long chip. The large SBS gain coefficient

(gB) of chalcogenide glass [4] (~ 100 x silica) allows

realization of large gain (G = gBIpLeff) in a photonic chip at

moderately low powers to selectively amplify a narrow band

of frequencies onto which the RF signal is encoded by

exploiting the narrow linewidth of the Brillouin gain

spectrum. Fig 1.C and Fig 1.D show that when the pump is

on, the signal at ωRF is filtered. Fig 1.E shows how

tunability is realized. An extinction of ~23dB, a narrow

3dB bandwidth of ~20MHz, 2-12 GHz of tunability and a

Q factor of ~600 were achieved.

In conclusion, we have reported the first demonstration of an on-chip, tunable narrow-bandpass microwave

photonic filter, by utilizing the narrow SBS linewidth and high SBS gain coefficient afforded by chalcogenide

glass [5] to selectively amplify a narrow band of frequencies.

References [1] W. Zhang, R.A. Minasian, "Widely Tunable Single-Passband Microwave Photonic Filter Based on Stimulated Brillouin Scattering,"

Photonics Technology Letters, IEEE , vol.23, no.23, pp.1775-1777, Dec.1, 2011

[2] J.Mora, B. Ortega, A. Diez, J. L. Cruz,M. V. Andres, J. Capmany, and D. Pastor, “Photonic microwave tunable single-bandpass filter based

on a Mach–Zehnder interferometer,” J. Lightw. Technol., vol. 24, no. 7, pp. 2550–2509, Jul. 2006.

[3] J. Palací, G.E. Villanueva, J.V. Galán, J. Martí and B. Vidal, “Single Bandpass Photonic Microwave Filter Based on a Notch Ring

Resonator”, Photonics Technology Letters, IEEE , Vol.22, pp.1276-1278, 2010.

[4] R. Pant, C. Poulton, D. Choi, H. Mcfarlane, S. Hile, E. Li, L. Thevenaz, B. Luther-Davies, S. Madden, and B. Eggleton, "On-chip stimulated

Brillouin scattering," Opt. Express, vol. 19, pp.8285-8290 , 2011.

[5] B.J. Eggleton, B. Luther-Davies, K. Richardson, “Chalcogenide Photonics”, Nature Photonics, pp. 141-148, 2011

Figure 1. a) Conceptual diagram. b) SEM cross-

section of chip. c) Spectra with pump off. d)

Spectra with pump on. e) Tunability concept

Fig 2. Experimental results displaying filter tunability

from 2-12 MHz (i-vi)

(i) (ii) (iv) (v) (iii) (vi)


57

W1 photonic crystal liquid waveguide

A. Casas Bedoya,1,* P. Domachuk,1 C. Grillet,1 C. Monat,2 E.C. Mägi, 1 E. Li,1 B. J. Eggleton,1

1Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS), Institute of Photonics and

Optical Science (IPOS), School of Physics, University of Sydney, New South Wales 2006, Australia 2Université de Lyon, Institut des Nanotechnologies de Lyon (INL)-UMR 5270, CNRS, Ecole

Centrale de Lyon, Ecully, FranceCentre for Ultrahigh bandwidth Devices for Optical Systems


We present an experimental demonstration of a reconfigurable single mode W1 photonic crystal defect waveguide created by

selective liquid infiltration. We modified a hexagonal silicon planar photonic crystal membrane by selectively filling a single

row of air holes with high refractive index liquid. The modification creates optical confinement in the infiltrated region and

allows propagation of a single optical waveguide mode.

In photonic crystal (abbrev. PhC) architectures leaving a row of holes out of the periodicity creates a defect that

allows light transport [1]; this configuration is well known as a W1 PhC waveguide. In this work we fabricate

the same configuration by modifying the refractive index of a single row of holes (air holes) in a PhC membrane

by optofluidic selective liquid infiltration [2, 3]. During this infiltration it is critical to have a stable micropipette

aligned to the target row on the sample and to have the right amount of pressure. If the pressure is to high, big

quantities of liquid are released and defects across the infiltration appear. Once this alignment is obtained, we

infiltrated the Γ-K direction of the PhC as showed in Fig. 1(a).

Fig. 1(b-c) shows the experimental transmission spectrum for the liquid waveguide is compared with its

theoretical dispersion diagram (left) for a PhC of 20μm length. In this diagram the green line represents the light

line, the red lines correspond to the PhC bulk modes and the blue lines are the symmetric and antisymmetric

(dotted line) waveguide modes. We see clearly a guided bandwidth frequency corresponding to the calculated

defect mode.

Fig. 1: (a) Microscope picture for a 20 µm W1 PhC liquid waveguide, created using selective infiltration. (b) Simulated

Dispersion diagram for an infiltrated PhC membrane with period a=390nm, r=0.32a and refractive index n=2.01 (c)

Experimental transmission spectrum the PhC liquid waveguide presented in (a)

References 1. T. F. Krauss, "Planar photonic crystal waveguide devices for integrated optics," Physica Status Solidi A-applied Research 197 (3), 688-702 (2003).

2. D. Erickson, T. Rockwood, T. Emery, A. Scherer, and D. Psaltis. “Nanofluidic tuning of photonic crystal circuits,” Opt. Lett. 31, 59–61(2006).

3. F. Intonti, S. Vignolini, V.Türck, M. Colocci, P. Bettotti, L. Pavesi, S.L. Schweizer, R. Wehrspohn, D. Wiersma. “Rewritable photonic circuits,”

Appl. Phys. Lett. 89, 211117 (2006)


58

Fast Simulation of Slab Photonic Crystal Structures using Modal Methods

P.Y. Chen1, R.C. McPhedran1, A.A. Asatryan2, L.C. Botten2, C.G. Poulton2, M.J. Steel3, C.M. de

Sterke1

1 CUDOS & IPOS, School of Physics, University of Sydney

2 CUDOS, School of Mathematical Sciences, UTS

3 CUDOS, Department of Physics and Astronomy, Macquarie University

Phone: 02 9351 6049 E-Mail: [email protected]

A faster method of simulating 2D slabs, both metallic and dielectric, with cylindrical inclusions is proposed. The method

can calculate both transmission spectra and in-plane modes.

Defect waveguides and cavities in slab photonic crystals and 2D transmission gratings in thin metal films

represent key platforms for optical devices in the fields of photonic crystals and plasmonics. Applications

include dispersion engineered slow light waveguides and plamon-induced field-enhancement based sensors.

However, the design of these devices often require lengthy parameter scans using numerical simulation tools

such as FTDT, FEM, or planewave expansions. We propose a new numerical tool which has the potential to offer

significant speed advantages in simulating 2D slab structures with periodic cylindrical inclusions. Restricting

attention to cylindrical inclusions allows the use of modal methods, which can describe the circular interface

between the slab and the inclusions with exponentially converging accuracy. This is especially advantageous in

plasmonic systems, where dense simulation grids are avoided and stair-case effect problems are eliminated. The

technique can produce transmission spectra due to an out-of-plane incident field, or find the in-plane defect

modes of the structure.

Our simulation technique builds upon our significant experience simulating cylindrical grating [1] and

cylindrical woodpile [2] structures. We use these techniques to simulate the desired structure, but with infinitely

long cylinders. This provides a basis for the in-slab Bloch modes, calculated by expressing boundary conditions

in terms of cylindrical harmonics and using lattice sums and transfer matrix techniques. Above and below the

slab, the plane-waves basis is used for the modes. Analytical expressions can be derived to convert between

these bases, which allows the calculation of transmission spectra and in-plane modes. Depending on the

simulation structure, we anticipate up to one or two orders of magnitude improvement over existing simulation

techniques.

References 1. G.H. Smith, L.C. Botten, R.C. McPhedran, N.A. Nicorovici, “Cylinder gratings in conical incidence with applications to

modes of air-cored photonic crystal fibers,” Phys. Rev. E, 66, 056604 (2002).

2. D.J. Kan, A.A. Asatryan, C.G. Poulton, and L.C. Botten, “Multipole method for modeling linear defects in photonic

woodpiles,” JOSA B, 27, 246-258 (2010)

Defect waveguide in photonic crystal slab Metallic transmission grating


59

Impact of cooling on Raman Scattering in an As2S3 Correlated Photon Pair Source

Matthew J. Collins, Alex S. Clark, Chunle Xiong, Eric Magi and Benjamin J. Eggleton



Phone: +612 9531 5978


In this paper we show a reduction of noise photons due to spontaneous Raman scattering in an As2S3 correlated

photon pair source, after cooling in liquid nitrogen. The improvement to the photon statistics is only significant in

the region close to the pump ∆f < 3THz and negligible for larger detuning.

Generation of photon pairs in the telecom band is attractive for quantum communication and requires sources

that are both bright and low noise. Although sources based on spontaneous parametric down conversion

(SPDC) in periodically poled lithium niobate (PPLN) waveguides [1], and spontaneous four wave mixing

(SFWM) in silicon nano-wires [2] and photonic crystals [3] have been widely studied, PPLN requires bulky

temperature control to achieve phase matching and silicon suffers from two-photon absorption. Recently,

Chalcogenide (As2S3) was presented as an attractive alternate platform for pair generation by SFWM, however a

limit in performance was observed due to spontaneous Raman scattering (SpRS) [4]. The generation of Raman

noise photons is significant within the SFWM bandwidth, for both Stokes and anti-Stokes shifts. We investigate

the impact of cooling to SpRS in As2S3 by measuring the photon statistics of correlated pair generation as well as

classically measuring the change in Raman gain at large pump detuning.

Fig. 1: The coincidence to accidental ratio (CAR), Fig. 2: The ratio between the number of SpRS noise

Measured at room temperature (red) and 77K (blue). Photons at room temperature (NRoom Temp) and 77K (N77K).

We measure the coincidence to accidental ratio (CAR) i.e. the ratio of correlated events to the system noise,

including detector dark counts, pump leakage, multiple-pair generation and SpRS noise photons. The maximum

CAR improved from 0.7 at room temperature to 4.8 at 77K (liquid N2), shown in Fig. 1. The detector settings and

coupled power were unchanged by the cooling, therefore dark counts, pump leakage and multi-pair generation

remain constant. We attribute the increase in CAR to a reduction in SpRS noise photons. Our setup can only

measure single photons within 1THz of the pump. The Raman gain was measured in As2S3 using a pump-probe

technique, exploiting the gain peak at ~10.3 THz from the pump. A drop in gain of only 1.2dB was observed for

the cooled fiber. Using a Bose-Einstein distribution for the phonon populations that mediate SpRS [5], we

modeled the expected number of noise photons at room temperature and 77K, (Fig. 2). The reduction in noise

photons is expected to be significant only for small detuning and negligible for large detuning, in agreement

with our measurements. Our work indicates that cooling As2S3 to 77K only improves the photon statistics of

correlated pair generation in the regime where the detuning of the idler and signal from the pump is small.

1. M. Hunault et. al., Opt. Lett. 35, 1239-1241 (2010).

2. S. Clemmen et. al., Opt. Lett. 35, 3483-3485 (2010).

3. C. Xiong et. al., Opt. Lett. 36, 3413 (2011).

4. C. Xiong et.al., App. Phys. Lett. 98 051101 (2011).

5. Y.Yamamoto and K. Inoue, Journal of LIghtwave Technology 21, 2895-2915 (2003).


60

2.04 μm Light Generation from a Ti:Sapphire Laser Using a

Photonic Crystal Fiber with Low OH loss

Stephen A. Dekker(1), Alexander C. Judge(1), Ravi Pant(1), Itandeh i Gris-S nche (2), Jonathan C.

Knight(2), C. Martijn de Sterke(1), Benjamin J. Eggleton(1) (1)CUDOS/IPOS, School of Physics, University of Sydney

(2)Centre for Photonics and Photonic Materials, Dept. of Physics, University of Bath

Phone: (02) 9481 6049


We report on the generation of 2.04μm light from an 801nm Ti:Sapphire source via soliton self-frequency shift and resonant

dispersive wave emission in a PCF with low OH loss and broad anomalous dispersion region.

Pulsed, wavelength tunable sources are desirable for numerous applications in areas such as communications

and analogue-to-digital conversion [1]. The soliton self-frequency shift (SSFS) has been exploited in the

realization of such sources. The maximum shift achievable in these experiments is limited on the long

wavelength side by the intrinsic absorption of silica at wavelengths above 2 μm [1]. Since the SSFS requires

anomalous dispersion, the separation of the first and second zero-dispersion wavelengths (ZDW) also limits the

maximum achievable red-shift. The ZDW at the blue end of the spectrum can be lowered by using photonic

crystal fibres (PCFs) with small cores, but this dramatically increases the OH loss peak at around 1400 nm [2]

thus creating an upper limit on the soliton shift when pumping at shorter wavelengths.

Figure 1. Schematic of the SSFS showing an input soliton

shifting from near the first to the second zero-dispersion

wavelength while crossing the traditional region of OH

absorption. Inset shows an SEM of the fibre core region.

Figure 2. PCF output spectra for a range of average input

powers. The pump wavelength and the longest wavelength

obtained are indicated with vertical dashed lines.

These limitations were overcome using a disperion engineered silica PCF (1.5 μm core diameter, 40m long) with:

(i) a reproducibly low OH attenuation of less than 0.06 dB/m [2], and (ii) widely spaced zero-dispersion

wavelengths at 700nm and 1840nm (see Fig. 1). Pumping the PCF using a Ti:sapphire laser (100fs pulses at

801nm, 14.9kW max. peak power), we measured an octave-spanning soliton shift from 801nm to 1883nm with

the farthest shifted soliton containing up to 52% of the output energy. Additionally, dispersive waves were

generated in the normal dispersion regime at 2040nm [3]. As shown in Fig. 2, the wavelength of the output

soliton could be tuned over this range by varying the average input power of the pump.

References 1. S. Oda and A. Maruta, “SSFS: Experimental Demonstrations and Applications,” Opt. Express 14, 7895, (2006).

2. I. Gris-Sánchez et. al., “Reducing spectral attenuation in small-core photonic crystal fibers,” Opt. Mater. Express 1, 179–184, (2011).

3. S. A. Dekker et. al., “Highly-Efficient, Octave Spanning Soliton Self-Frequency Shift Using a Specialized Photonic Crystal Fiber with Low

OH Loss,” Opt. Express 19, 17766-17773, (2011).


61

Control of dense carbon nanotube arrays via hierarchical multilayer catalyst

C. Fisher, Z. J. Han, I. Levchenko and K. Ostrikov

CSIRO Materials and Science Engineering – Lindfield

& School of Physics, University of Sydney

Phone: (02) 9413 7173


Effective control of dense, high-quality carbon nanotube arrays using hierarchical multilayer catalyst patterns is

demonstrated. Scanning/transmission electron microscopy, atomic force microscopy, Raman spectroscopy, and numerical

simulations show that the density of vertically aligned nanotubes can be varied by changing the thickness of Al, Al3O2 and

Si substrate layers. The results are explained in terms of the substrate structure effect on carbon diffusivity.

Arrays of carbon nanotubes (CNTs) are the focus of much research due to their excellent mechanical, chemical

and electronic properties. These properties allow CNT arrays to be implemented in many applications such as

biosensors, photovoltaic cells and many others. [1] Their favourable properties are particularly prominent in

arrays with uniform length, diameter, orientation, chirality, and structure. [2] Existing fabrication techniques do

not offer sufficiently high levels of control over the CNT structure and characteristics, thus demanding further

research efforts.

In this study [3], the influence of the complex multilayer hierarchical catalyst structure on the growth of

nanotube arrays is demonstrated by growing three CNT samples on three different substrates of Al, Al2O3 and

SiO2 layers of various thicknesses. It was found after scanning/transmission electron microscopy, atomic force

microscopy and Raman spectroscopy that the carbon nanotubes had vastly different CNT densities, even

between the two samples that had similar catalyst surface morphologies. Figure 1 (a) and (b) show a typical CNT

sample grown. Using numerical simulations as in Figure 1 (c), we explained that this difference in CNT was due

to the 3-5% change in surface activation energy caused by the thickness of the substrate layers. Hence, small

surface activation energy can be used as effective controls of the CNT array growth in future.

Fig. 1: Experimental carbon nanotube array images from (a) scanning electron microscope and (b) transmission electron

microscope; and (c) numerical simulation of carbon atom density in monolayers on surface of substrate. [3]

References 1) J. N. Coleman, U. Khan, W. J. Blau, Y. K. Gun’ko “Small but strong: A review of the mechanical properties of carbon nanotube-polymer

composites,” Carbon 9, 1624/44, (2006).

2) M. S. Dresselhaus, G. Dresselhaus, J. C. Charlier, E. Hernandez, “Applications of carbon nanotubes in the twenty-first century,” Philosophical

Transactions of the Royal Society a-Mathematical Physical and Engineering Sciences 362, 2065/1823, (2004).

3) C. Fisher, Z. J. Han, I. Levchenko, K. Ostrikov, “Control of dense carbon nanotube arrays via hierarchical multilayer catalyst”, Applied Physics

Letters 99, 3104/14, (2011).



62

Q-switched Holmium fibre laser operating at 2.9 µm

Tomonori Hu, Darren D. Hudson, Benjamin J. Eggleton, Stuart D. Jackson


CUDOS/IPOS, School of Physics, University of Sydney

Phone: 9351 6048


We demonstrate the first pulsed emission of a Holmium-praseodymium (Ho3+Pr3+) fibre laser operating at 2.9µm. Q-

switching was achieved by acousto-optic modulation, producing 100 ns pulses with maximum peak power of 40W, with a

variable repetition rate from 100 to 300 kHz. An efficiency of 20% with respect to the launched pump power was measured.

Lasers operating in the 3 µm region have major applications in

medical and sensing technologies due to water having strong

absorption of radiation at this wavelength [1]. By using these

laser sources in pulsed operation, nonlinear optical effects can

be performed such as self-phase modulation and super

continuum generation. Q-switched lasers based on Erbium

have been demonstrated at 2.800 µm [2] using acousto-optic

modulators (AOMs). However, Holmium-doped lasers have

an advantage that they offer tuneable emission from 2.825 µm

to 2.900 µm, at higher efficiencies compared to Erbium lasers

[3].

Here a TeO2 AOM is placed in the Ho3+Pr3+ laser cavity for Q-switched operation (see Fig. 2). Diodes at 1.150 µm

pump the Ho3+Pr3+ doped ZBLAN fibre and RF pulses drive the AOM. Q-switching was achieved by increasing

the cavity Q-factor when the AOM was on, and a pulse is produced when it is turned off. A stable pulse train is

produced at the output where the pulse widths are 100 ns (see Fig. 3a). By adjusting the pump power and

repetition rate, the laser produces stable pulse trains from 100kHz to 300 kHz. At the maximum pump power,

the laser produces pulse trains with a peak power of 40W. The spectrum is centred at 2.865 µm, which to the best

of our knowledge, is the longest wavelength emitted by a Q-switched fibre laser (see Fig. 3b). This laser opens

exciting applications in mid-infrared photonics such as nonlinear optics in chalcogenide waveguides, and

resonator optics in micro-cavities for sensing technologies.

References [1] G. M Hale and M. R. Querry, “Optical constants of water in the 200 nm to 200 μm wavelength region” Appl. Opt., 12, pp. 555-563 (1973)

[2] S.Tokita, M. Murakami, S. Shimizu, M. Hashida, and S. Sakabe, "12 WQ-switched Er:ZBLAN fiber laser at 2.8 μm," Opt. Lett. 36, pp. 2812-2814 (2011)

[3] D. Hudson, E. Magi, L. Gomes and S. D Jackson, “1W diode-pumped tunable Ho3+Pr3+-doped fluoride glass fibre laser,” Elec. Lett. 47, pp.

985-986 (2011)

Fig 2. Absorption of water showing the 3 µm peak

[1]

Fig. 2. Experimental setup of Q-switched fibre laser Fig. 3. (a) Pulse train produced at 110 kHz; inset showing

wave form (b) Spectra of pulse train, centred at 2865 nm


63

A flexible method to find Bloch modes, complex band structures, and impedances of two-

dimensional photonic crystals

Felix J. Lawrence, Lindsay C. Botten, Kokou B. Dossou, R. C. McPhedran, and C. Martijn de Sterke


IPOS and School of Physics, University of Sydney

Department of Mathematical Sciences, University of Technology, Sydney

Phone: +61 2 9036 5187


We present a method to calculate Bloch modes, complex band structures, and impedances of two-dimensional photonic

crystals (PCs) from scattering data produced by widely available software packages. The method combines previous work on

PC impedances [1], which relied on specialized software, with work based on that of Ha et al. [2], which can calculate Bloch

modes and complex band structures from scattering data. Software that implements the method is available online [3].

Photonic crystal impedance is a powerful concept that encapsulates all the information about a PC’s Bloch

modes that is required to calculate its reflection and transmission properties [1]. Together with the PC’s

complex band structure, impedances allow efficient calculation of the reflection and transmission properties of a

combinatorial multitude of PC stacks. This has practical applications in designing PC antireflection coatings [1],

and in investigating PC waveguide or PC surface modes. However, PC impedances were previously defined in

terms of scattering matrix-derived quantities, that could be directly calculated only by our highly specialized

software that is not openly available. We present a method to extract a PC’s propagating and evanescent Bloch

modes from generic field scattering data, and to calculate the PC’s impedance from the extracted modes.

Our method for finding the Bloch modes is based on that of Ha et al. [2]: we take scattering data for several PC

periods, and use least squares techniques to write it as a superposition of Bloch modes. The data may be

generated by widely available software, or potentially a SNOM experiment. For better accuracy we impose a

number of symmetry constraints, exploiting the relationship of forward/backward Bloch mode pairs’ fields.

Impedances are calculated by writing each Bloch mode’s field along a unit cell’s edge as a superposition of plane

waves given by the grating equation. The relative amplitudes of these plane waves for each mode give the

quantities with respect to which PC impedances are usually defined [1].

To demonstrate our method, we use it to calculate the impedances of 121 candidate PCs for an antireflection

coating, and find that the calculated reflectances in the coating’s parameter space (see Fig. 1) is nearly

indistinguishable from that calculated from highly accurate impedances calculated with multipole methods [1].

For this particular example, the reflectivity is reduced from 0.943 to less than 0.001 by adding two rows of holes

to the front of the PC, where their spacings from each other and the PC are adjustable parameters. References

[1] F. J. Lawrence, L. C. Botten, K. B. Dossou, and C. M. de Sterke, Appl. Phys. Lett. 93, 121114 (2008).

[2] S. Ha, A. A. Sukhorukov, K. B. Dossou, L. C. Botten, C. M. de Sterke, and Y. S. Kivshar, Opt. Lett. 34, 3776 (2009).

[3] https://launchpad.net/blochcode

Fig. 1: Reflectance of a two-layer coating

for a PC. The degrees of freedom are ay1

and ay2, the relative spacing in the y-

direction of the first two rows of holes:

for an unperturbed lattice, ay 2/√3 = 1. PC

is air holes with radius 0.25 a in n = 2.86

background, with lattice constant a.

Reflectances are at frequency a/λ = 0.38,

at an incident angle of 30˚, with E field

polarized out of the plane.

https://launchpad.net/blochcode


64

Radiation calculations in photonic crystal cavities using a basis of bound states

S. Mahmoodian, J.E. Sipe, C.G. Poulton, K.B. Dossou, R.C. McPhedran, L.C. Botton and C.M. de

Sterke

CUDOS, School of Physics, University of Sydney

Phone: +61 02 9036 5187


We develop a formulation to compute the radiation from double heterostructure cavity (DHC) modes using a basis of bound

states. By expanding the DHC mode using a basis of photonic crystal waveguide modes that are below the light line, we are

able to derive an equation for the radiative Fourier components of the cavity mode. We use this to efficiently compute the far

field radiation pattern and quality factor of DHC modes.

Optical cavities that spatially confine light over periods of many optical cycles are much sought after

devices. Recently, much research has been undertaken to use photonic crystal (PC) bandgaps to create cavities

with large quality factors [1]. The double-heterostructure cavity (DHC) is one such cavity type that enables an

ultra high quality factor (Q-factor) with a modal volume on the order of the wavelength cube. The DHC consists

of a PC slab waveguide being weakly perturbed to increase the amount of dielectric in a spatial region. This

creates a localized mode in the perturbed region which is bound to the waveguide due to bandgap effects but

cannot propagate along the waveguide due to the edges of the perturbation acting like mirrors. The out of plane

confinement is due to total internal reflection (TIR); the cavity’s quality factor is limited by the number of

Fourier components of the cavity mode that satisfy the TIR condition.

Computing the modes and Q-factors of DHC cavities is typically done using finite difference time

domain (FDTD) calculations. Such calculations become very time consuming when the Q-factor of cavity modes

is ~106. In this abstract, we report on our development of a method to compute the mode of DHC cavities and

their quality factors. The first part of our theory is based on a Hamilonian formulation, which has previously

been used to formulate coupled mode equations in waveguiding structures [2]. Here, since the DHC can be

thought of as a weak perturbation to a photonic crystal waveguide (PCW), we expand the DHC mode using a

basis of the PCW modes that lie below the light cone that are computed using FEM or plane wave expansion

methods. Using this expansion we formulate a perturbed Hamiltonian for the DHC, which essentially entails

populating a matrix of overlap integrals between the modes at each Bloch wavevector under the light-cone and

the perturbation to the PCW that creates the DHC cavity. Diagonalising this matrix gives the frequency of the

DHC mode and a representation of the mode in our basis of PCW Bloch modes. We now use this solution to

perturbatively compute the radiative states of the DHC cavity.

By using a Green’s tensor for layered media [3] and

our solution of the DHC cavity using the basis of bound

states, we are able to derive a self consistent representation of

the radiative polarization states in the form of an integral

equation. By solving this equation we are able to compute

the quality factor and farfield radiation pattern of DHC

modes. Figure 1 shows a comparison between the quality

factor computed using FDTD methods and our theory for a

DHC cavity created by changing the background index of a

W1 PCW slab with air hole radius a=0.3, from n=2.7 to

n=2.72. There is good agreement between the theory and

FDTD calculations, particularly for wide cavities. Our theory

shows promise for being used as a design tool for tailoring

the radiation properties of PC cavities.

References [1] T. Asano et al IEEE Journal of Selected Topics in Quantum Electronics 12, 6/1123, 2006

[2] P. Chak et al PRE 75, 016608, 2007

[3] J.E. Sipe J. Opt. Soc. Am. B. 4, 4 1987

Figure 1 Q factors for DHC cavity as a function of

Cavity length for FDTD calculations (Blue line)

and our theory (red line)



65

Drawn meta-material for electric response in the mid IR

Osama Naman, Alexander Argyros, Alessandro Tuniz, Simon C. Fleming and Boris T. Kuhlmey

Institute of Photonics and Optical Science (IPOS), School of Physics, The University of Sydney

CUDOS, School Of Physics, The University of Sydney

Institute for Laser for Postgraduate Studies, University of Baghdad, Iraq

Phone: +61412234129


Recently, conventional fiber drawing techniques have been developed to draw composite structure of indium and PMMA

for the fabrication of metamaterials with responses in the THz frequencies. We investigate extending this technique to

fabricate metamaterials for the mid-IR. In this work we consider a metamaterial consisting of a wire array with plasma

frequencies between 15-30 THz, corresponding to 10-20 μm wavelengths.

Metamaterials are composite materials with structure on a scale much smaller than the wavelength. These

artificial materials can have properties that cannot be found in nature, and can in principle allow the permittivity

and permeability of the material to be tuned, with potential applications in guiding light and bending light

around obstacles, thus rendering them invisible. Since the materials are structured on a scale much smaller than

the wavelength, it is very hard to fabricate them for visible wavelengths, particularly in large quantities.

Recently, we developed a new technique to fabricate microstructured electric metamaterials. This method allows

us to fabricate micro-wires embedded in dielectric material in such an arrangement that gives the desired

characteristics, i.e. allowing control over the plasma frequency of the composite material and hence its

permittivity at a particular frequency. Most bulk metals have a plasma frequency at visible and UV frequencies,

however such metal wire arrays have shown the ability to push the plasma frequency to THz [1] and to the IR

for the same metals. The relatively longer wavelength of THz radiation means the structures are easier to

fabricate, so the wire diameters have been about 10-100 microns, using indium metal wires embedded in a

PMMA background. Our work aims to extend this into the mid-IR where the dimensions required are 1 µm

wires and 5 µm of lattice spacing. In order to have structure on a scale smaller than half the wavelength, the wire

diameter must be less than 0.28 of the lattice spacing. We are thus aiming to fabricate electric metamaterials with

plasma frequencies between 15-30THz, corresponding to 10-20 μm wavelengths which match a transparency

window in the PMMA.

Fig. 1: Left: Image of one of the intermediate stages of fabrication, showing an indium wire array in PMMA. The wires used

in the fabrication were 1 mm in diameter and were drawn to 10 μm (shown here), a further reduction by ×10 is required.

Right: Plasma frequency as a function of wire diameter/spacing and lattice spacing.

References [1] A. Tuniz et al., “Drawn metamaterials with plasmonic response at terahertz frequencies”, Appl. Phys. Lett. 96 191101 (2010).

0 0.5 1 1.5 2 2.5 3

x 10-5

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Wire Spacing (m)

Dia

mete

r / S

pacin

g

Fp=3 THz

Fp=15 THz

Fp=20 THz

Fp=25 THz

Fp=30 THz

Fp=100 THz


66

Automatic multi-order dispersion compensation for 1.28 Terabaud transmission

Yvan Paquot1, Jochen Schröder1, Jürgen Van Erps1,2, Trung D. Vo1,

Mark D. Pelusi1, Steve Madden3, Barry Luther-Davies3 and Benjamin J. Eggleton1


Institute of Photonics and Optical Science (IPOS)

School of Physics A28, University of Sydney, NSW 2006, Australia, 2Vrije Universiteit Brussel, Brussels Photonics Team, Dept. of Applied Physics

and Photonics, Pleinlaan 2, 1050 Brussel, Belgium, 3CUDOS, Laser Physics Centre, Australian National Univ., Canberra A.C.T. 0200, Australia


We demonstrate simultaneous automatic compensation for the 2nd, 3rd and 4th orders of dispersion on a single channel

OTDM link at 1.28Tb/s. Dispersion compensation is performed by a spectral pulse shaper and signal monitoring by a chip-

based all-optical RF spectrum analyzer.

High bandwidth OTDM signals [1] are increasingly susceptible to impairments. In addition to group velocity

dispersion (GVD), higher-orders of dispersion significantly affect the transmission. An accurate dispersion

compensation solution is therefore crucial [2]. We demonstrate automatic and simultaneous compensation of the

second, third and fourth orders of dispersion (β2, β3 and β4) for a 1.28 Tb/s single channel OTDM signal. Our

scheme combines all-optical measurement of a single parameter from the RF-spectrum of the signal to monitor

the impairments, and spectral pulse-shaping to compensate for dispersion [3]. The RF spectrum is measured

with a Terahertz bandwidth all-optical RF spectrum analyzer implemented using a chalcogenide photonic chip

[4]. A scalar optimization algorithm tunes recursively all three orders of dispersion with a view to maximize the

1.28THz tone power of the RF spectrum that reflects the quality of the signal.

Fig. 1: Automatic dispersion compensation scheme: the 1.28 Tbaud transmitter is followed by a link emulating both initial

residual dispersion and dispersion fluctuations. The combination of a signal monitor with a dispersion compensator allows

for automatic compensation of those fluctuations simultaneously for β2, β3 and β4. The compensation scheme is based on

maximizing the 1.28 THz tone power of the RF spectrum of the signal (right insert).

References [1] H. Hansen Mulvad, L. Oxenlø we, M. Galili, A. Clausen, L. Gruner-Nielsen, and P. Jeppesen, “1.28 Tbit/s singlepolarisation serial OOK

optical data generation and demultiplexing,” Electronics Letters 45, 280–281 (2009).

[2] J. Van Erps, J. Schroeder, T. Vo, M. Pelusi, S. Madden, D. Choi, D. Bulla, B. Luther-Davies, and B. Eggleton, “Automatic dispersion

compensation for 1 . 28Tb/s OTDM signal transmission using photonic-chip-based dispersion monitoring,” Optics Express 18, 25415–25421 (2010).

[3] M. A. F. Roelens, S. Frisken, J. A. Bolger, D. Abakoumov, G. Baxter, S. Poole, and B. J. Eggleton, “Dispersion Trimming in a Reconfigurable

Wavelength Selective Switch,” Lightwave 26, 73–78 (2008).

[4] M. Pelusi, F. Luan, T. D. Vo,M. R. E. Lamont, S. J. Madden, D. A. Bulla, D.-Y. Choi, B. Luther-Davies, and B. J. Eggleton, “Photonic-chip-

based radio-frequency spectrum analyser with terahertz bandwidth,” Nature Photonics 3, 139–143 (2009).



67

Absorption of Silicon Nanowire Arrays on Silicon and Silica Substrates

Björn Sturmberg





68

Fibre Metamaterials with Magnetic Resonances in the Terahertz Range

Alessandro Tuniz, Alexander Argyros, Simon C. Fleming and Boris T. Kuhlmey



Phone: +61 (0)2 9351 5978


We produce metamaterial fibres containing slotted metallic cylinder resonators. We experimentally and numerically

characterize such fibres, which possess magnetic resonances between 0.1-0.4 THz. These structures are a further

demonstration of bulk-produced 3-dimensional metamaterials in fibre form, with a number of potential applications.

Electromagnetic metamaterials allow manipulation of light in ways not possible in nature by tailoring the

effective response of subwavelength “atoms”. Fabrication techniques from the THz into the visible are expensive

and labour-intensive, and can only be used up to the centimetre scale. Fibre drawing has emerged as a means of

inexpensively producing bulk, three-dimensional metamaterials; this has been used to produce fibres containing

continuous metal wires [1], and fibers with retrieved negative permeability in the THz, via a two-step procedure

[2]. More recently [3], we produced hundreds of meters of direct-drawn metamaterial fibers with a magnetic

response in the THz range using two methods: the first involved preparing a macroscopic polymer preform

containing a slotted indium cylinder, heating it and drawing it directly to a fiber containing a single magnetic

resonator; the second method extended this procedure, whereby many such fibers were arranged in a preform,

and subsequently re-drawn to a slab containing smaller resonators [3]. We experimentally characterised the

transmittance of single and multiple layers of such drawn structures at terahertz frequencies, finding good

agreement with numerical finite-element simulations. This procedure can be scaled to smaller dimensions for

operation at higher frequencies, by further drawing the structures presented. Additionally, one should be able to

extend this technique to direct-draw double slotted-cylinder resonators or swiss-roll geometries, to reduce the

ratio of resonator size with respect to resonance wavelength. Combined with the previously presented

fabrication of fiber-drawn metal-wire metamaterials this could enable the development of woven negative index

materials, as well as the fabrication of subwavelength waveguides. Advanced weaving techniques could even

allow production of materials with gradients of permittivity and permeability.

Figure 1: Left: A cm-sized polymer preform containing an indium slotted-cylinder tube is drawn into fibres of different diameters. Middle:

Each fibre is inserted into a rectangular Zeonex preform, which is re-drawn down to rectangular fibers. Right: Experimentally measured

(top) and simulated (bottom) transmittance for fibers of different diameters d shown left (blue: 350m; green: d=300m; red: d=250m).

References [1] A. Tuniz et al., “Drawn metamaterials with plasmonic response at terahertz frequencies”, Appl. Phys. Lett. 96 191101 (2010).

[2] A. Wang et al., "Fiber metamaterials with negative magnetic permeability in the terahertz," Opt. Mat. Express 1, 115 (2010)

[3] A. Tuniz et al., “Stacked-and-drawn metamaterials with magnetic resonances in the terahertz range,” Opt. Express 19, 16480 (2011)

1.9mm



69

Tunable Nonlinear Response of Split Ring Resonators

Kirsty Hannam, David Powell, Ilya Shadrivov, and Yuri Kivshar


Nonlinear Physics Centre, Australian National University

Phone: 612 61259077


We investigate the tunability of the nonlinear shift between two Split Ring Resonators (SRRs), by changing both the

incident power, and the mutual orientation of the rings.

Engineered metamaterials consisting of a lattice of sub wavelength, resonant elements have been shown to have

unique properties, such as a negative refractive index [1]. An important element is the split ring resonator (SRR),

which may have a negative magnetic response [2]. Unlike the atoms in natural materials, the near-field patterns

within metamaterials are quite complex, giving rise to strong interaction between neighbouring elements. By

controlling the relative arrangement of elements, it is possible to change this coupling and tune the properties of

the structure [3, 4]. The properties of individual metamaterial elements can also be controlled with an external

signal, by inserting nonlinear inclusions such as diodes which may also have power-dependent resonant

frequencies [5, 6].

We have experimentally demonstrated

control of the nonlinear response of two

broadside-coupled SRRs, by modifying

the offset between them.

To do this, we perform microwave

experiments with SRR pair, having an

offset δa between their centres, as

shown schematically in Fig. 1. The rings

are printed on opposite sides of FR4 circuit board, with a varactor

across a second gap on each ring. The absorption spectra are measured

for offsets δa, at low and high power.

We measure the relative difference between the low and high power

resonant frequencies for each value of δa, as shown in Fig. 2, for both

the symmetric and antisymmetric modes. These modes are defined by

the relative directions of the currents on the rings and are both tunable

through a change of δa [3, 4]. The inset in Fig. 2 shows the nonlinear shift for the symmetric at one offset. We

observe a significant decreasing trend in the nonlinear frequency shift for the symmetric mode, as a function of

the linear offset.

In conclusion, we have demonstrated that by shifting two coupled SRRs relative to each other, we can control

the nonlinear properties of both resonant modes in the system. We expect our results will stimulate further work

in controlling and designing nonlinear properties of metamaterials.

References [1] D.R. Smith, W.J. Padilla, D.C. Vier, S.C. Nemat-Nasser, and S. Schultz, “Composite medium with simultaneously negative permeability and

permittivity,” Phys. Rev. Lett. 84, 4184 (2000).

[2] J.B. Pendry, A.J. Holden, D.J. Robbins, and W.J. Stewart, “Magnetism from conductors and enhanced nonlinear phenomena,” IEEE Trans.

Microwave Theory Tech. 47, 2075 (1999).

[3] M. Lapine, D.A. Powell, M.V. Gorkunov, I.V. Shadrivov, R. Marques, and Y.S. Kivshar, “Structural tunability in metamaterials,” App. Phys.

Lett. 95, 084105-3 (2009).

[4] D.A. Powell, M. Lapine, M.V. Gorkunov, I.V. Shadrivov, and Y.S. Kivshar, "Metamaterial tuning by manipulation of near-field interaction,"

Phys. Rev. B 75, 195111-8 (2010).

[5] I.V. Shadrivov, S.K. Morrison, and Y.S Kivshar, "Tunable split-ring resonators for nonlinear negative-index metamaterials," Opt. Exp. 14, 9344-

9349 (2006).

[6] D.A. Powell, I.V. Shadrivov, Y.S. Kivshar, and M.V. Gorkunov, “Self-tuning mechanisms of nonlinear split-ring resonators,” App. Phys. Lett.

91, 144107-3 (2007).

Fig. 2: The nonlinear shift as a function

of δa. The inset shows the change in

frequency between two curves for the

symmetric mode.

Fig. 1: Schematic of broadside-

coupled rings shifted by offset

δa, with inserted diodes.


70

Optimization of Multi-layer Fishnet Optical Metamaterials

Sergey S. Kruk*, Alex E. Minovich, David A. Powell, Dragomir N. Neshev, and Yuri S. Kivshar

Nonlinear Physics Centre and Centre for Ultrahigh bandwidth Devices for Optical Systems

RSPE, Australian National University


We study optical properties of multi-layered fishnet metamaterials depending of several design parameters. In particular, we

show how the optical transmission, refractive index and figure of merit depend on the index of the dielectric spacer in the

functional fishnet layer, as well as their dependences on the geometry of the effective meta-atoms.

Multi-layer Fishnets (MF) are promising structures for the realization of NIMs in optics. In particular, the highest

figure of merit (FOM) was experimentally achieved in such structures [1]. Due to their low losses, bulk

properties, and possibilities for easy fabrication, such multi-layer fishnet materials have been the subject of

intense research interest. Here we present the analysis of the optical properties of such MF systems depending

on several design and structural parameters. The basic design of MF is the geometry of Double Fishnets

structures [2] that is repeated by stacking several of such double layers together. This results in a multi-layer

metal-dielectric structure as shown in the inset of Fig. 1(e). Important structural parameters in such MFs are the

thicknesses of different layers, the geometry of the holes, and the refractive index of the dielectric layer.

Fig. 1. (a) Transmission, (b) neff and (c) FOM versus wavelength and refractive index of the dielectric spacer. Dashed line

marks wavelength 1400nm. (d) Transmission, (e) neff and (f) FOM respectively versus refractive index of dielectric at the

wavelength of 1400 nm. Inset: MF structure where a=500 nm, wx=351 nm, wy=100 nm, thickness of metal (silver) layer 45 nm

and thickness of dielectric layer 30 nm.

In Fig. 1 we show the dependence of optical properties - optical transmission [Fig. 1(a)], overall refractive index

[Fig. 1(b)], and Figure of merit defined as the ration of the real to imaginary part of the refractive index - on the

refractive index of the dielectric spacer. The band of high transmission and FOM shifts linearly in wavelength

with an increase of the dielectric index. The determined dependence opens a way for a control of macroscopic

optical parameters of the MFs and the development of amplifying bulk MF metamaterials.

References [1] J. Valentine, et al., “Three-dimensional optical metamaterial with a negative refractive index”, Nature, 455, 376-380 (2008).

[2] G. Dolling, et al., “Design-related losses of double-fishnet negative-index photonic metamaterials”, Opt. Express, 15, 11536-11541 (2007).


71

Optical activity and coupling in twisted dimer metamaterials

Mingkai Liu, David Powell, Ilya V. Shadrivov, Yuri S. Kivshar



Phone: 61258093


We analyse the optical activity in metamaterial dimers (Fig. 1) by introducing a simple yet accurate semi-analytical model

for the coupling between them. The near-field interaction coefficients are derived from a Lagrangian model and include the

effects of retardation, whereas the far-field radiation is based on a multipole expansion. This efficient approach is accurate

over a wide frequency range and it requires no fitted parameters or homogenization procedure.

We first numerically find the charge ( , )t r and current distribution ( , )tJ r for a single wire, and separate

them into a time-dependent mode amplitude ( )Q t and spatially dependent parts ( , )q t r and ( , )tj r . The self

and mutual electric and magnetic interaction energies can then be calculated rigorously as follows [1,2] : *

3 30,

0

( ) ( ')exp( | ' |)'

8 | ' |E mn

Vm Vn

q q ikW d r d r

r r r r

r r,

*3 30 0

,

( ) ( ')exp( | ' |)'

8 | ' |M mn

Vm Vn

ikW d r d r

j r j r r r

r r

with , (1,2)m n . Following Ref. 3, the Lagrangian of the twisted dimer can be written as.

2 2 2 2

1 2 1 2 1 2 1 2 1 2

1( 2 ) ( 2 )

2 2

i

M E

LQ Q Q Q Q Q Q Q e

C

p E p E

In which the coupling parameters E and M can be calculated rigorously from ,E mnW , ,M mnW . By solving the

Euler-Lagrange equation, we obtain the amplitudes of charge and subsequently, the far-field scattering spectra

based on a multipole approximation. The results show an overall good agreement with the full-wave simulation

from CST-Microwave studio, as shown in Fig. 2.

This method can be further extended as an efficient tool for the future exploring on other chiral and hybrid

structures. The approach can also be extended to include the coupling between neighboring elements in an

array.

Fig. 1(left): Schematic layout of the twisted cut-wire pair. a=6mm, t=0.1mm, w=1mm and s=1mm. The metal is copper and the background

is vacuum. The incident wave is polarized in the y direction, parallel to cut-wire 1. Fig. 2(right): Amplitudes and phases of the electric

field of forward radiated wave at z=20mm, under different twist angle. (a,b) theta=0o (c,d) =20o (e,f) =45o . The results from

mutipole approximation (m.) and CST-MWS are plotted in (---) and (◊)respectively.

References

1. Radkovskaya, A. and Tatartschuk, E., etc. “Coupling between split rings: an experimental, numerical and analytical study,” 2nd International

Congress on Advanced Electromagnetic Materials in Microwaves and Optics, Pamplona, Spain, September 21-26 (2008).

2. Powell, D.A. , Lapine, M., etc. “Metamaterial tuning by manipulation of near-field interaction,” PRB 82, 155128, (2010).

3. Liu H., Cao JX, Zhu SN, etc. “Lagrange model for the chiral optical properties of stereometamaterials,” PRB 81, 241403, (2010)


72

Polarization independent Fano resonances in arrays of core-shell nanospheres

Wei Liu*, Andrey E. Miroshnichenko, Dragomir N. Neshev, and Yuri S. Kivshar


Nonlinear Physics Centre, The Australian National University


We reveal the existence of polarization-independent Fano resonances in one dimensional arrays of core-shell nanospheres

which exhibit both electric and magnetic Mie resonances engineered to overlap spectrally with the same strength. The

electric and magnetic Mie resonances can interfere simultaneously with the geometrical resonance (the so-called Wood's

anomaly) of the periodic array, resulting in polarization-independent Fano resonances.

The studies of sharp Fano resonances in periodic metallic structures have recently attracted surging attention

due to their promising applications, including near-field amplification, sensing, and modification of

spontaneous emission [1-3]. The Fano resonance originates from an interference between Wood's anomaly and

plasmon resonances [1]. However, due to the electric nature of the plasmon resonance, the sharp resonances in

one dimensional (1D) periodic arrays are strongly polarization dependent. Although this polarization

dependence could be avoided by deploying two-dimensional (2D) symmetric lattices, the 2D structures are not

as efficient as 1D ones [2] and can prevent the miniaturization of future Fano resonance based. We demonstrate

that the polarization-independent Fano resonances can be achieved in 1D arrays of nanoparticles through the

hybridization of magnetic and electric Mie resonances in metal core-dielectric shell nanospheres and their

interference with the Wood's anomaly of the array.

FIG. 1. (a) Extinction spectra for core-shell sphere width inner radius 38 nm and outer radius 150 nm. The electric and

magnetic resonances coincide spectrally with the same strength. (b) The geometry of the structure we study. (c) Theoretical

and (d) FDTD results of the extinction spectra for an infinite array of core-shell spheres with d=1.15 μm.

In Fig. 1(a) we show the total extinction spectra of a silver core dielectric shell sphere of inner radius 38 nm and

outer radius 150 nm. We also show the contribution from both electric (a1) and magnetic (b1) dipoles. It is clear,

for this structure there are both electric and magnetic dipolar resonances. More importantly, for the specific

inner and outer radius ratios, the two resonances could coincide spectrally with the same intensity. Here we

investigate 1D periodic particle arrays as shown in Fig. 1(b). In our study we fix the wavevector of the incident

plane wave along z. This is because when the wavevector direction deviates from z direction, the Fano

resonances will split into two resonances with reduced resonance strengths [3]. For the array of core-shell

nanospheres, both electric and magnetic resonances contribute to the Fano resonance, making the resonance

very weakly sensitive to the incident polarization. In Fig. 1(c) and 1(d) we show polarization independent

extinction spectra of the array of 1D infinite core-shell nanoparticles, calculated by theory and FDTD simulation,

respectively. For finite 1D structures, the polarization independent feature of Fano resonances is preserved.

The polarization independence of the obtained Fano resonance represents a significant advance in the

understanding of the scattering of hybrid particle arrays, with a number of important applications in sensing,

near field enhancement, nano-antennas and spaser-based nanolasers.

References: [1] A. E. Miroshnichenko, S. Flach, and Yu. S. Kivshar, "Fano resonances in nanoscale structures,'' Rev. Mod. Phys., 82, 2257 (2010).

[2] S. L. Zou, N. Janel, and G. C. Schatz, "Silver nanoparticle array structures that produce remarkably narrow plasmon lineshapes,'' J. Chem.

Phys., 20, 10871 (2004).

[3] V. A. Markel, "Divergence of dipole sums and the nature of non-Lorentzian exponentially narrow resonances in one-dimensional periodic

arrays of nanospheres,'' J. Phys. B.: Mol. Opt., 38, L115 (2005).


73

Control of Photon-Pair Generation and Spatial Quantum State

in Waveguide Arrays with Cubic Nonlinearity

Alexander S. Solntsev, Andrey A. Sukhorukov, Dragomir N. Neshev, and

Yuri S. Kivshar


Nonlinear Physics Centre, RSPE, Australian National University

Phone: +61-2-6125-9075


We analyze the process of photon pair generation realized by spontaneous four-wave mixing in nonlinear waveguide arrays,

where the pump beam can exhibit self-focusing. We demonstrate that this platform allows for flexible control of photon-pair

spatial correlations, including transition between bunching and anti-bunching statistics by tuning the pump intensity.

One of particularly interesting devices in integrated photonics is a waveguide array. Recently waveguide arrays

have been shown to generate unusual and strongly non-classical correlations of photon pairs propagating in the

regime of quantum walks [1]. Combining quantum walks with photon pair generation in nonlinear waveguide

arrays opens the possibility for enhanced spatial quantum state control and improved clarity of spatial

correlations [2]. However, only the waveguide arrays with quadratic nonlinearity have been studied so far. With

photon-pair sources based on waveguides with cubic nonlinearity being readily available [3], it becomes of

much importance to study the photon-pair quantum states in waveguide arrays with cubic nonlinearity.

Fig. 1: (a) A nonlinear waveguide array. (b,d) Pump intensity distribution along the waveguide array and (c,e) photon-pair

correlations in the case of zero dispersion for (b,c) low-power pump diffraction and for (d,e) high-power pump soliton

formation. (f) Photon-pair bunching to antibunching ratio vs. pump amplitude for normal and anomalous dispersion.

We consider an array of coupled waveguides in cubic nonlinear media [Fig. 1(a)], where photon pairs are

generated through near-degenerate spontaneous four-wave mixing (SFWM). We demonstrate that for zero

dispersion and low-intensity pump which exhibits discrete diffraction [Fig. 1(b)], the signal and idler photons

feature spatial bunching statistics, i.e. the photons are most likely to emerge from the same waveguides at the

output [Fig. 1(c)]. However when the pump power is increased and the pump beam exhibits self-focusing [Fig 1

(d)], the spatial photon-pair correlations change to predominantly anti-bunching regime, where photons tend to

emerge from the opposite waveguides [Fig. 1(e)]. The tuning of spatial correlations by the pump power can be

further tailored by engineering the waveguide dispersion [Fig. 1(f)]. We anticipate that our results will open new

opportunities for integrated quantum photonics.

References [1] A. Peruzzo, M. Lobino, J. C. F. Matthews et al., Science 329, 1500 (2010).


[3] J. E. Sharping, K. F. Lee, M. A. Foster et al., Opt. Express 14, 12, 388 (2006).


74

Optical forces between longitudinally shifted nano-beam cavities

Yue Sun1,2 and Andrey Sukhorukov1 1 Nonlinear Physics Centre and 2Laser Physics Centre, Research School of Physics and Engineering,

Australian National University, Canberra, Australia

Phone: 61259077


We reveal that gradient optical forces between side-coupled nano beam-cavities can be flexibly controlled by introducing a

relative longitudinal shift. We predict that the transverse force depends almost periodically on the longitudinal shift.

Additionally the shift leads to symmetry breaking that can facilitate longitudinal forces acting on the beams, in contrast to

unshifted structures where longitudinal forces vanish.

Development of reconfigurable photonic circuits utilizing gradient optical forces opens new possibilities for

optical signal shaping and routing based on all-optical tuning of the structure geometry. Optomechanical

interactions can be enhanced in coupled-cavity structures due to increased sensitivity of optical modes to

mechanical deformations and increased optical energy concentration in the cavities. Strong optomechanical

interactions have been demonstrated experimentally between suspended nanobeam cavities [1]. The sign and

strength of optical forces depends on the transverse separation between the cavities and the type of optical

mode.

We suggest that optical forces can be flexibly controlled through the introduction of a longitudinal shift between

the cavities [Fig. (a)], extending the concept which we previously introduced for force control between periodic

nano-waveguides [2]. We predict using analytical coupled-mode theory and confirm with direct three-

dimensional (3D) numerical simulations, that the transverse force between the cavities (Fy) depends almost

periodically on the longitudinal shift [Fig. (b)]. This allows one to vary the strength of the force, while keeping

the overall geometry of the waveguides fixed which can facilitate integration of such elements onto photonic

chips where light coupling could be optimized for particular transverse separation between the nano-

waveguides. The longitudinal shift also breaks the reflection symmetry of the coupled-cavity structure and this

leads to the appearance of a longitudinal force (Fx), which is absent for unshifted cavities [Fig. (c)].

We further demonstrate that tailored control over the optical gradient forces enables one to tune the dynamical

behaviour associated with light-induced mechanical vibrations [3]. Specifically, it becomes possible to control

optomechanical oscillations by combined excitation of two optical modes, enabling new multistability regimes.

Fig: (a) Side-coupled nanobeam cavities with longitudinal shift s. (b) Transverse and (c) longitudinal force vs. the

longitudinal shift. Open circles Maxwell stress tensor method using 3D FDTD simulation result. Solid line coupled mode

theory.

References [1] M. Eichenfield, R. Camacho, J. Chan, K. J. Vahala, and O. Painter, Nature 459, 550 (2009).

[2] Y. Sun, T. P. White, and A.A. Sukhorukov, arXiv: 1111.0437 (2011).

[3] F. Marquardt, J. G. E. Harris, S. M. Girvin, Phys. Rev. Lett. 96, 103901 (2006).

0 0.5 1 1.5-1

0

1

2

3

4

5x 10

-5

longitudinal shift/a

Fy

(b)

mode 1

mode 2

0 0.5 1 1.5-1.5

-1

-0.5

0

0.5

1

1.5x 10

-5

Fx

longitudinal shift/a

(a)

mode 1

mode 2

(b) (c)

(a)


75

Optical annealing of thermally evaporated Ge-As-Se thin films

Xueqiong Su, Rongping Wang, Duk Yong Choi, Steve Madden, Barry Luther-Davies

Centre for Ultrahigh bandwidth Devices for Optical Systems, Laser Physics Centre, The Australian

National University

Phone: 02-61251591


Ge-As-Se thin films with different compositions were deposited using thermal evaporation methods, and then they were

irradiated using a LED illuminator with an emission wavelength of 656nm and an energy density of 7.5×10-2W/cm2. The

films irradiated with different exposure time were subsequently measured using FilmTex, and the physical parameters like

optical bandgap, refractive index was investigated as a function of LED irradiated flux. The correlation between the

evolution of the physical parameters, irradiated flux, and chemical compositions of the films were emphasized.

Chalcogenide glasses are promising for applications in photonics since they have large third optical nonlinearity,

low phonon energy, low optical losses and so on. An issue that limits the practical application of the materials in

photonics is its structural stability. The performance of the photonics devices is always degraded by the

structural relaxation in the films. Therefore it is critical to find the films with proper chemical compositions and

stable structure against any optical irradiation or thermal annealing.

In this work, we prepared a series of Ge-As-Se films with different chemical compositions using thermal

evaporation methods, and then irradiated these films using a LED illuminator that is commercially available.

The films with different irradiation flux were subsequently measured using Film Tex and number of physical

parameters such as optical bandgap and refractive index for each film were recorded as a function of irradiation

flux. The typical results of refractive index and optical band as function of irradiation flux were sown in Figure 1

and 2, respectively. On-going experiments are still in progress, particularly we will pay attention to the

correlation between the evolution of the physical parameters, irradiated flux, and chemical compositions of the

films

References 1. D.A.P.Bulla, R.P.Wang, A.Prasad, A.V.Rode, S.J.Madden, B.Luther-Davies, “On the properties and stability of thermally evaporated Ge-

As-Se thin films,” Appl. Phys. A 96, 615-625, (2009)

2. Keiji Tanaka, “Photoinduced processes in chalcogenide glasses,” Solid State & Materials Science 1, 567-571, (1996)


76

EXAFS study of the local order in Ge-As-Se glasses

T. Wang, R. P. Wang, D. Y. Choi, S. Madden, A. Smith and Barry Luther-Davies


Laser Physics Centre, Australian National University

Phone:02 6125 0694


The nearest-neighbour environment of the Ge, As and Se atoms in GexAsySe1-x-y with same mean coordination number

(MCN=2.5) have been investigated by the extended X-ray absorption fine structure (EXAFS) spectra. The results indicate

that chemical order is preserved in stoichiometric and Se-rich glasses where Ge and As atoms predominately form

heteropolar bonds with Se atoms. Some homopolar bonds are found in Se-poor glasses indicating violation of chemical order.

Understanding of the glass structure has been a challenging issue since there is no long-range order in the

glass, and thus all the techniques that are based on diffraction methods to identify the periodic structure in the

crystalline solids are generally inapplicable to glass materials. Extended X-ray absorption fine structure (EXAFS)

seem to be a powerful tool to get the information like chemical bond length, chemical angle, and coordination

number of each element. In the work, we measured the K-edge extended X-ray absorption fine structure spectra

of five pieces of ternary Ge-As-Se glasses in with the same mean coordination number (MCN) of 2.50 but

different chemical compositions. We found that, irrespective of glass composition, Ge, As and Se are always 4, 3

and 2 coordinated, respectively. Ge and As are found to be bonded only to Se atoms in the stoichiometric and

Se-rich glasses, showing preservation of chemical order. “Wrong” homopolar bonds are formed exclusively

between As atoms in Se-poor glasses suggesting violation of chemical order and clustering of As atoms. The

topological consequences of these structural units can be indispensable to explain the compositional variation of

properties in chalcogenide glasses.

4 6 8 10 12

Ge20

As10

Se70

Ge15

As20

Se65

Ge12.5

As25

Se62.5

Ge10

As30

Se60

Ge7.5

As35

Se57.5

k3

(k)

k (Angstrom-1)

(a)

4 6 8 10 12

(b)Ge

20As

10Se

70

Ge15

As20

Se65

Ge12.5

As25

Se62.5

Ge10

As30

Se60

Ge7.5

As35

Se57.5

k3

(k)

k(Angstrom-1)

Fig. 1 Simulations of k3-weighted Ge(a) and As(b) K-edge EXAFS spectra. Solid lines represent experimental data and dashed lines

correspond to fitting results.

References 1 J. C. Phillips, “Topology of covalent non-crystalline solidsⅠ:short-range order in chalcogenide alloy,” J. Non-Cryst. Solids. 34, 153(1979).

2 D. Arsova, “Bond arrangement and optical band gap in GexAs(40-x)S(Se)60 glasses and thin films, ” J. Phys. Chem. Solids. 57, 1279(1996).

3 S. Shukla, S. Kumar, “Role of Sb incorporation on the electrical and photoelectrical properties of Se-In glassy alloy,” J. Non-Cryst. Solids. 357, 847

(2011).



77

Thermal characterization of Ge-Sb-Se chalcogenide glasses

W. H. Wei, R. P. Wang, T. Wang, Z. Y. Yang, D. Y. Choi, S. Madden, X. Shen and Barry Luther-

Davies


Laser Physics Centre, Research School of Physics and Engineering, Australian National University

Phone: 04 2668 1045


The thermal kinetics parameters of 24 pieces of ternary Ge-Sb-Se chalcogenide glasses have been measured using differential

scanning calorimetry (DSC) under non-isothermal conditions at different heating rates ranging from 7 to 30K/min. The

correlation between mean coordination number (MCN) and glass transition temperature (Tg) [1], glass transition

activation energy (Ea) [2] were discussed.

In chalcogenide glass science it has been arguable that the physical properties of the glasses are dominated by

mean coordination number (MCN: defined as a sum of the respective elemental concentrations times their

covalent coordination number) rather than chemical compositions. This has been demonstrated in Ge-As-Se

glass systems where various physical properties, like density, elastic moduli, refractive index, and optical

bandgap show transitions at two magic numbers of MCN= 2.4 and 2.67 [3], respectively. However, it is highly

desirable that such a concept should be examined. In order to test whether the existence of these two magic

numbers is generally in other material systems. Therefore in the present study, we prepared 24 pieces of Ge-Sb-

Se bulk glasses, and employed differential scanning calorimetry to measure the various thermal kinetics

parameters of the glasses. We aim at understanding the correlation between chemical compositions, MCN and

physical properties of Ge-Sb-Se chalcogenides.

The present results indicate that: (1) the glass transition temperature Tg increases with increasing MCN from 2.2

to 2.8; (2) the glasses with same MCN but different chemical compositions show minor variation about their

thermal parameters; (3) chemically stoichiometric Ge-Sb-Se glasses display the activation energy increases with

MCN from 2.5 to 2.65.

References 1. J.C. Phillips, “Topology of covalent non-crystalline solids:short I-range order in chalcogenide alloys,” Journal of Non-Crystalline Solids, 34,

153(1979).

2. R. Böhmer, K.L. Ngai, and C.A. Angell, “Nonexponential relaxation in strong and fragile glass formers,” Journal of Chemical Physics, 99,

4201(1993).

3. K. Tanaka, "Structural phase transitions in chalcogenide glasses," Journal of Physics Review B, 39, 1270(1989).



78

Photoluminescence of erbium doped stable Ge-Ga-Se chalcogenide glasses

Kunlun Yan, Rongping Wang, Zhiyong Yang, Anita Smith, Wenhou Wei, and Barry.Luther-Davies


Laser Physics Centre, Research School of Physics and Engineering, the Australian National

University


Various Gex–Gay–Se1-x-y glasses have been investigated using Raman spectroscopy and differential scanning calorimetry in

order to find stable host for erbium element. The result showed that glasses with stoichiometric composition Ge17Ga15Se68

and Ge23Ga12Se65 are more stable in structure and thermal properties, therefore, erbium doped Ge17Ga15Se68 and Ge23Ga12Se65

glasses were prepared and optical properties were investigated. The 1.54 μm emission arising from the 4I13/2→4I15/2 transition

was observed and lifetimes of 1.44ms and 1.63ms were obtained.

Fig. 1: Raman spectra for GeGaSe glasses Fig. 2: Plot of decay curves for Er doped samples

In order to find a stable host for erbium, four pieces of Ge–Ga–Se glass samples with different compositions

were prepared. Raman spectra were performed to investigate the structures, thermal properties were studied by

using DSC, and crystallization was observed in two of the samples. After this, glasses with compositions

Ge17Ga15Se68 and Ge23Ga12Se65 were chosen to dope with 2 mol% erbium for their outstanding performance in

structure stability and thermal properties. In both of the erbium doped glasses, emission around 1.54 μm arising

from the 4I13/2→4I15/2 transition was observed and lifetimes of 1.44ms and 1.63ms were obtained. These results

indicate that Er doped Ge17Ga15Se68 and Ge23Ga12Se65 glasses should be promising candidates for optical

amplifiers based on Chalcogenide glass.


79

Nonlinear chalcogenide gyroids fabricated with direct laser writing

Benjamin P. Cumming1, Mark. D. Turner1, Sukhanta Debbarma2,

Barry Luther-Davis2, Gerd E. Schröder-Turk3, and Min Gu1

Centre for Ultrahigh bandwidth Devices for Optical Systems 1Centre for Micro-Photonics, Swinburne University of Technology

2Laser Physics Centre, Australian National University 3Theoretische Physik, Friedrich-Alexander Universität Erlangen-Nürnberg

Phone: +61 (0)3 9414 4303


We present the fabrication of three-dimensional (3D) gyroid network structures via direct laser writing (DLW) in high

refractive-index and highly nonlinear arsenic trisulfide (As2S3) thick films. We show that aberration compensation can be

utilised to dramatically increase the fabrication quality, and present our progress on employing a dynamic slit method for

the fabrication of gyroid structures where the DLW process retains the original cubic chiral symmetry.

The Gyroid (or srs) network is a cubic network with chiral symmetry I4_132. It has been shown to exhibit strong

circular dichroism [1,2], and can be further engineered by the interweaving of multiple gyroid networks. By

fabricating in evaporatively deposited thick films of As2S3, a large refractive index contrast can be produced,

allowing strong optical interaction with the gyroid networks. The nonlinearity of the As2S3 also provides the

opportunity to exploit active functionality in these novel chiral materials.

In this work we apply aberration and elongation compensation to gyroid network fabrication in As2S3 via a

simple spatial light modulator. The aberration compensation counteracts the spherical aberration introduced by

focusing into the high refractive index of As2S3 which is mismatched with the refractive index of the microscope

objective immersion medium. This permits us to fabricate with near diffraction limited performance throughout

a large depth of material so that uniform, mechanically stable and high resolution gyroid network structures are

achievable in As2S3. Following this, an elongation compensation scheme was developed that would allow us to

fabricate gyroid network structures where the DLW process retains the original cubic chiral symmetry. This

involved placing a phase ramp onto a slit shaped section of the beam so that it was allowed to pass a pinhole

placed at the focus of a lens. Once collimated, the beam has a slit like amplitude distribution that can be directed

into a microscope objective. This amplitude distribution expands the lateral size of the focal spot to a much more

symmetric shape [3] so that the original cubic chiral symmetry of our gyroid networks is preserved.

Fig. 1: Gyroid network structures fabricated in As2S3 without (left) and with (right) compensation of the

refractive index mismatch aberration. Both structures have the same fabrication power, lattice constant and size.


Opt. Express 19, 10001-10008 (2011).

[2] M. Saba et al., "Circular Dichroism in Biological Photonic Crystals and Cubic Chiral Nets,", Phys. Rev. Lett. 106, 103902 (2011).

[3] Ya Cheng, Koji Sugioka, Katsumi Midorikawa, Masashi Masuda, Koichi Toyoda, Masako Kawachi, and Kazuhiko Shihoyama, “Control

of the cross-sectional shape of a hollow microchannel embedded in photostructurable glass by use of a femtosecond laser,” Opt. Letters 28,

55-57 (2003).


80

Spontaneous emission enhancement with defects in a three dimensional pseudo-gap

photonic crystal

Zongsong Gan1, Baohua Jia1, Jingfeng Liu2, Xuehua Wang2 and Min Gu1 1Centre for Micro-Photonics & CUDOS, Faculty of Engineering and Industrial Sciences, Swinburne

University of Technology 2School of Physics and Engineering, Sun Yat-Sen (Zhongshan) University, P. R. China

Phone: (03) 92144303


For a three-dimensiona) pseudo-gap photonic crystal, due to the overlapping and dispersoid of different direction stop gaps,

it is difficult to observe the enhancement of emission at the emission wavelength of the stop gap band edge in the Г-X. Defect

can effectively change the local density of states in PC. By induce plane defect, 15% emission lifetime decrease was achieved.

Spontaneous emission (SE) is a fundamental basis for diverse everyday applications in photonics[1]. Inhibition

of SE with a photonic band gap has been recognised. Compared with SE inhibition, SE enhancement is also

important for the control of SE. A general viewpoint to realise SE enhancement with a photonic crystal (PC) is

related to the band edge enhancement [2]. A low refractive index 3D pseudo-gap PC has different properties

from a high index 3D complete band gap PC. Different directions exhibit different stop gaps, making the band

edge phenomenon for low refractive index 3D pseudo-gap PC not as clear as the complete band gap PC.

We first measured the change of the SE at the band edge and the band centre for a 3D pseudo-gap PC fabricated

by two-photon polymerization with Ormocer (Micro Resist Technology). PbSe/CdSe quantum dots (QDs) were

used as SE probes. Fig.1 (left) shows that SE is inhibited at the gap centre and up band edge in the Г-X direction.

No band edge enhancement was observed. This is explained as the overlapping and dispersoid of different

direction stop gaps. The experimental results have been supported by the theoretical prediction.

To realise SE enhancement with a 3D pseudo-gap PC, a defect was induced. By induce a plane defect (the PC

without a defect is a 24 layers woodpile structure, the defect is induced by 10% of the PC lattice distance longer

of the 12th and 13th layer distance), the LDOS at the position of the defect is greatly changed. Thus, 15% emission

lifetime decrease was achieved at the centre position of the defect (as shown in Fig.1. (right)).

Fig.1: Left: SE lifetime of QDs for different emission wavelengths in a PC compared with that in reference free space. The

wavelength of 1480nm is the gap centre in the Г-X direction and the wavelength of 1350 nm is the up band edge. Right: SE

lifetime of QDs at different depths for the emission wavelength that matches the gap centre of the PC, with and without a

defect, compared with that in reference free space.

1. J. J. Wierer, A. David, and M. M. Megens, "III-nitride photonic-crystal light-emitting diodes with high extraction efficiency", Nat. Photon 3,

163-169 (2009).

2,K. Kuroda, T. Sawada, T. Kuroda, K. Watanabe, K. Sakoda, “Doubly enhanced spontaneous emission due to increased photon density of

states at photonic band edge frequencies”, Optics Express 17, 13168 (2009)


http://dx.doi.org/10.1364/OE.17.013168

http://dx.doi.org/10.1364/OE.17.013168


81

Theoretical modeling of doughnut beam based superresolution photoinhibition-induced

nanolithography

Zongsong Gan, Yaoyu Cao, Baohua Jia and Min Gu

CUDOS, Faculty of Engineering and Industrial Science, Swinburne University of Technology,

Phone: (03) 94124303

E-Mail: ([email protected])

A kinetic coupling model for the superreslution photoinhibition-induced nanolithography has been established based on the

photo-physics and photo-chemistry process in photopolymerisation. Numerical simulation results for the dot fabrication

indicate an un-synchronized change of dot feature size and shortest dot separation distance as against the change of the

inhibition strength. This work shows the great potential for its application in the nanofabrication

Superresolution photoinhibition-induced nanolithography (SPIN) has received increasing attention for its

potential to fabricate structures in the nanometer scale, far beyond the diffraction limit [1]. Resolution

improvement can be achieved by overlapping a doughnut-shaped inhibition beam and an induction beam in the

Gaussain mode in the focal region. The induction laser beam is used to generate free radicals and to initiate

photopolymerisation while the doughnut beam is used to produce inhibitor radicals and to stop the

photopolymerisation in the outer ring of the doughnut beam. As a result, the photopolymerisation is confined at

the centre of the focus region, which leads to a smaller dot feature size and a smaller shortest dot separation

distance (nearest separated neighboring dot centre distance) beyond the diffraction limit.

A kinetic coupling (KIC) model is developed to simulate the SPIN system. In this model, all the parameters used

in the calculation are based on the materials used in the reference [1]. The effectiveness of the model is validated

by comparing the calculation with the doughnut beam inhibited single-photon polymerisation experimental

results. A 300 nW fabrication beam ( λ =480 nm) is used to polymerise the photo-sensitive material. When a 7 μ

W inhibiting doughnut beam ( λ =375 nm) was on, the size of dot is decreased from the original 1230 nm to 360

nm. A continue increasing of the inhibition laser beam power can decrease the dot feature size to below 100 nm.

However, the calculation indicates that the shortest dot separation distance is not always reduced while the

doughnut beam power increases as shown in Fig.1. This can be attributed to the side reaction of the inhibitor

radicals with monomer to initiate polymerisation, although the polymerisation rate is relatively slow. The un-

synchronised change of dot feature size and shortest dot separation distance indicates an optimised condition

for complex structure fabrication using this fabrication technique.

. 0 10 20 30 40 50

0

200

400

600

800

1000

1200

1400

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nm

UV power (W)

shortest dot separation distance

dot feature size

Fig. 1: Dot feature size changes un-synchronized with shortest dot separation distance as against the UV inhibition laser

power

[1] T. F. Scott, B. A. Kowalski, A. C. Sullivan, C. N. Bowman and R. R. McLeod, Two-color single-photon photoinitiation and photoinhibition

for subdiffraction photolithography, Science, 324, 913, 2009

http://www.sciencemag.org/search?author1=Timothy+F.+Scott&sortspec=date&submit=Submit

http://www.sciencemag.org/search?author1=Benjamin+A.+Kowalski&sortspec=date&submit=Submit

http://www.sciencemag.org/search?author1=Amy+C.+Sullivan&sortspec=date&submit=Submit

http://www.sciencemag.org/search?author1=Christopher+N.+Bowman&sortspec=date&submit=Submit

http://www.sciencemag.org/search?author1=Robert+R.+McLeod&sortspec=date&submit=Submit


82

Nanometer localization of single semiconductor quantum dots inside a three-dimensional

photonic crystals

Zongsong Gan1,2, Betty Kouskousis1, and Min Gu1,2 1Centre for Micro-Photonics and 2Centre for Ultrahigh-bandwidth Devices for Optical Systems,

Faculty of Engineering and Industrial Science, Swinburne University of Technology

Phone: (03) 92144303


Using a super-resolution technique together with the temporal differential fluorescence signal properties of single quantum

dots, nanometre localisation of single quantum dots localisation of single quantum dots embedded inside a three-

dimensional photonic crystal has been demonstrated. This technique provides a new platform to investigate the local optical

properties of photonic crystals.

To investigate the local optical properties of a photonic crystal, small fluorescent probes can be used to show the

optical properties of the position where the probes are. In this work, a super-resolution imaging technique which

utilising the stochastically temporal photoluminescence of quantum dots as a function of time [1] is employed to

resolve single emitters inside a three-dimensional photonic crystal and provide information about the localised

optical properties.

As proof of concept, a woodpile photonic crystal was fabricated using the two-photon-polymerization method

in Ormocer (Micro Resist Technology) [2]. CdSe/CdS core shell semiconductor quantum dots were synthesized

and connected to the surface of the photonic crystal structure via molecular linking. The absorption spectrum of

these quantum dots is shown in Fig. 1 left. Using an Olympus IX71 inverted microscope together with a 100X 1.4

NA objective, a time lapse sequence of single quantum dots embedded within the photonic crystal structure was

acquired. Single quantum dots were imaged using a continuous-wave excitation source, operating at a

wavelength of 405 nm. As shown in Fig.1 right, single quantum dot emission on the surface of the photonic

crystal can be observed.

As it is well known quantum dots display considerable interruptions in their photoluminescence that can vary

considerably in duration under continuous-wave excitation, a phenomenon known as “blinking”. Using this

phenomenon as a function of time together with a home developed algorithm, quantum dots embedded within

the crystal that are located within a diffraction limited area can be localised with nanometre precision.

550 600 650 7000

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2

3

4

5

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sorp

tion

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nit)

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Fig. 1: left: Absorption spectrum of CdSe/CdS core shell quantum dots; right: Fluorescence wide-field imaging of the same

quantum dots deposited woodpile photonic crystal

1. Betty P. Kouskousis, Joel van Embden, Dru Morrish, Sarah M. Russell and Min Gu, J. Biophotonics, 3(7), 437 (2010)

2. Martin Straub and Min Gu, Optics letters 27, 1824 ( 2002)


83

Spontaneous emission control with three-dimensional hybrid photonic crystals

Zhengguang He, Zongsong Gan Baohua Jia, Min Gu

Centre for Micro-Photonics and CUDOS, Faculty of Engineering and Industrial Sciences,

Swinburne University of Technology, Australia


Near-infrared emitting core-shell quantum dots have been incorporated into hybrid photonic crystals fabricated using the

two-photon direct laser writing method combined with a metallic silver surface functionalisation. Modification of

spontaneous emission has been observed in this unique platform combining the photonic bandgap and the localised plasmon

resonance.

Recently, intensive experimental and theoretical research has been conducted on hybrid (metallo-dielectric)

photonic crystals (HPCs) [1]. HPCs can possess a complete band gap when the metallic layer is thick. While

reducing the thickness of the metallic layer in HPCs can lead to localised plasmon resonances (LPRs). This

special platform will eventually provide a unique environment for the controlling of the spontaneous emission

once a proper luminescent emitter is introduced

1000 2000 3000 4000 5000

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50

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70

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ctio

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)

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standard lattice constant

smaller lattice constant

larger lattice constant

LPRscomplete band gaps

Fig. 1: (a) SEM image of a woodpile PC structure after silver coating through an electroless deposition method. (b) Fourier

transform infrared spectroscopy (FTIR) results of 3D HPCs with different lattice constants.

In this paper, by using the two-photon polymerisation technique, woodpile PCs with high quality have been

fabricated using IPL (Nanoscribe GmbH) as the photoresin. A modified Tollens reaction was used for isotropic

deposition of silver on complex three-dimensional (3D)geometries [2] with thicknesses in the 40-50 nm range

and good smoothness (Fig.1 (a)). The FTIR spectra show LPR effect and complete band gaps effect (Fig.1 (b)). For

the control of the spontaneous emission, PbSe-CdSe core-shell quantum dots (QDs) have been synthesised and

introduced to HPCs by drop casting. Afterwards we realised a reduced lifetime of the QDs due to LPRs

enhancement of the spontaneous emission.

Reference: [1] J. Li, MD.M.Hossain, B. Jia, Dario Busoand M. Gu, Three-dimensional hybrid photonic crystals merged with localized plasmon

resonances, Opt.Express Vol.18,No.5 10740 (2010).

[2] Malureanu R, Zalkovskij M. Andryieuski A., Lavrinenko A.V. Journal of The Electrochemical Society, 157, K284 (2010).

(a)



84

Ultrahigh nonlinearity in nanoshell plasmonic waveguides

Md Muntasir Hossain, Mark Daniel Turner, and Min Gu


Centre for Micro-photonics, Swinburne University of Technology

Phone: +61392144303


Optical nonlinearity within subwavelength waveguides is a key element for realising nanophotonic chips. Here, we propose

a novel subwavelength nanoshell nonlinear plasmonic waveguide which possesses ultrahigh Kerr nonlinearity with total

energy confinement.

Dielectric nonlinear waveguides are constrained to possess high nonlinearity due to their fundamental limitation

of mode confinement beyond the diffraction limit. Plasmonic waveguides offer an unmatchable ability for

confining the mode far beyond the diffraction limit. However, achieving high nonlinearity in plasmonic

waveguides is still a challenge due to the evanescent nature of the electromagnetic fields within plasmonic

waveguides. We theoretically demonstrate that a new kind of plasmonic waveguide can achieve ultrahigh

nonlinearity and complete mode confinement. Our design is a metallodielectric plasmonic waveguide which

comprises of a high refractive index subwavelength nonlinear core embedded within a metallic nanoshell [1].

The deep subwavelength mode confinement and the vectorial nature of the modal fields result in ultrahigh Kerr

nonlinearity within the plasmonic waveguide. Our results show that reducing the nonlinear core size of the

nanoshell waveguide and providing dispersion engineering the nonlinear nanoshell plasmonic waveguide can

possess an ultrahigh Kerr nonlinearity up to 1.02×104W-1m-1 with nearly 100% of the mode energy residing inside

the waveguide at λ = 1.55 μm.

Figure 1 (a) The plasmon mode electric field distributions of the plasmonic waveguide for a chalcogenide nanowire core

width of 100 nm, an aspect ratio of 3 and a silver nanoshell of thickness of 50nm. (b) Calculated Kerr nonlinearity within the

waveguide for varying core width of the nonlinear waveguide core.

Figure 1a shows the calculated electric field distribution of the plasmon mode within the subwavelength

plasmonic waveguide at the wavelength of 1.55 µm where the nonlinear core is a chalcogenide nanowire [2].

Figure 1b shows the calculated Kerr nonlinearity of the plasmonic waveguide by using a full vectorial model [3].

References 1. M. M. Hossain, M. D. Turner, M. Gu, “Ultrahigh nonlinear nanoshell plasmonic waveguide with total energy confinement,” Opt. Express, 19,

23800-23808, (2011).

2. E. Nicoletti, D. Bulla, B. Luther-Davies, and M. Gu, "Generation of λ/12 Nanowires in Chalcogenide Glasses," Nano Letters, 11, 4218-4221,

(2011).

3. V. S. Afshar, T. M. Monro, "A full vectorial model for pulse propagation in emerging waveguides with subwavelength structures part I: Kerr

nonlinearity," Opt. Express 17, 2298-2318 (2009).



85

Broadband nanofocusing of light in dielectric chalcogenide glass nanogratings

Han Lin, Qiming Zhang, Min Gu


Swinburne University of Technology, PO Box 218, Hawthorn VIC 3122, Australia

[email protected]

Broadband nanofocusing of light energy in chalcogenide glass nanogratings is investigated using the FDTD method. It is

shown that the modes coupled into the nanogratings can be confined into an ultra-small focal volume ( 3 / 8500 ) with an

ultra-high power efficiency (up to 80%).

The emerging researches of nanofocusing[1-3] of optical energy addresses the critical challenge of manipulating

light on scales much smaller than the traditional diffraction limit. However, studies of nanofocusing have only

been demonstrated using surface plasmon polaritons on metal nanostructures. This approach suffers high

optical losses and requires stringent fabrication techniques and the designed structures can only operate at a

single resonance wavelength. Here, we propose a new approach of nanofocusing the optical energy by using

dielectric chalcogenide glasses nanogratings. The chalcogenide glass nanogratings consist of three nanoslits with

finite length embedding in a chalcogenide glass bulk material. The interaction between the eignmodes in the

nanoridges between the nanoslits enables the ‘capacitor-like’ energy storage that allows effective nanofocusing

in low-index regions. In this way, we are able to compress the optical energy into an ultra-small focal volume

( 3 / 8500 ) in the slit of the nanogratings with an ultra-high energy efficiency (80%). This approach is fully

compatible with semiconductor fabrication techniques and could lead to truly nanoscale semiconductor-based

photonics. Our work opens the way to development of sensing tools based on the optical near-field waves,

including miniaturised spectrometers and lab-on-a-chip integrated sensors.



86

Generate multifocal diffraction-limited non-Airy pattern arrays for large area parallel

fabrication of novel metamaterials

Han Lin and Min Gu


Swinburne University of Technology, PO Box 218, Hawthorn VIC 3122, Australia

[email protected]

Multifocal diffraction-limited split-ring-resonator (SRR) arrays are generated using the Debye integral method. By using

multifocal SRR arrays, large area metamaterials as SRR as unit cells can be fast parallel fabricated.

Photonic metamaterials are man-made structures composed of tailored micro- or nanostructured metallic or

dielectric subwavelength building blocks which are able to realise many new and unusual optical properties,

such as negative refractive index, zero reflection through impedance matching, giant circular dichroism and

enhanced nonlinear optical properties [1]. Possible applications of metamaterials include ultrahigh-resolution

imaging systems, compact polarization optics and cloaking devices. The direct laser writing (DLW) technique

provides high spatial resolution and allows for the fabrication of novel three-dimensional (3D) metamatrials

which cannot be fabricated using any other methods [2]. In a DLW set up, a laser beam can only be focused into

a diffraction-limited Airy pattern, and through scanning the focal spot along designed trajectory, arbitrary

structures can be fabricated. However, the speed of fabrication is limited by the scanning stage or the other light

steering devices and only a small portion of the laser power has been used. In this paper, we show that by

modulating the wavefront of a laser beam, we are able to create a non-Airy focal pattern such as a split-ring-

resonator (SRR) in the focus with the Debye integral method [3]. Thus an array of diffraction-limited non-Airy

patterns can be generated, which allows the true scan-free laser printing fabrication [3]. In this way, 2D or 3D

functional metamaterials can be fast fabricated with a speed enhancement of more than two-orders.

Fig. 1a, Intensity distribution of single SRR focus; b, Intensity distribution of a generated SRR multifocal array; c, Schematic

of designed 2D SRR array structures

References 1. C. M. Soukoulis and M. Wegener, Nat. Photon, 5, 523 (2011).

2. Gansel, J. K. et al. Science 325, 1513 (2009).

3. H. Lin, B. Jia and M. Gu, Opt. Lett. 36, 406 (2011).


87


Achieving true cubic symmetry in three-dimensional biomimetic chiral photonic

microstructures via galvo-mirror dithering

Mark D. Turner1,2, Gerd E. Schröder-Turk3, Ben Cumming1 and Min Gu1

1Centre for Micro-Photonics and CUDOS, Faculty of Engineering and Industrial Science,

Swinburne University of Technology, Australia, VIC 3122. 2CRC for Polymers, 8 Redwood Drive, Notting Hill, Australia, VIC 3168.

3Theoretische Physik, Friedrich-Alexander Universität Erlangen-Nürnberg,

Staudstr. 7B, Erlangen, Germany.

Phone: 03 9214 4303


We will present our recent developments on biomimetic three-dimensional microstructures with chiral photonic properties

at telecommunications wavelengths. By applying a galvo-mirror dithering method to direct laser writing, we have greatly

improved the mechanical strength of this fabrication method, corrected the intrinsic asymmetry of the focal spot and

improved the photonic properties.

Previously we reported on the fabrication and characterisation of chiral photonic crystals [1] whose design was

inspired by recent theoretical findings [2] of circular dichroism bands in the wing-scales of a butterfly. These

micro-engineered photonic crystals showed circular dichroism bands in the mid-infrared wavelengths.

However, the direct laser writing (DLW) method used to fabricate these structures has an intrinsic asymmetry

due to the unavoidable elongation of the diffraction limited focal spot. This leads to a breaking of the cubic

symmetry of the design, affecting both the mechanical and optical properties. Here we present a solution where

a galvanometer mirror is used to dither the DLW focal spot in a continuous small circular pattern to compensate

for this elongation asymmetry. As shown in Figure 1a-c, a structure that is initially mechanically unstable (Fig.

1a), can be made mechanically stable through galvo-dithering (Fig. 1c), greatly improving the uniformity of

these periodic microstructures. This improvement allows us to achieve smaller unit cell sizes of down to 1.3 μm

with measured circular dichroism bands now in the telecommunications wavelengths as shown in Fig. 1d. These

results provide the opportunity to develop functional devices such as chiral beamsplitters or chiral superprisms

at the telecommunications wavelengths.

Fig. 1: a-c) Scanning electron microscope image of three chiral networks fabricated using direct laser writing under the same

fabrication conditions except with (a) no galvo-dithering, (b) small galvo-dithering and (c) more galvo-dithering.

d) Transmission spectra of a chiral srs-network with unit cell size 1.3 μm, showing strong circular dichroism at

telecommunications wavelengths.


Opt. Express 19, 10001-10008 (2011).

[2] M. Saba et al., "Circular Dichroism in Biological Photonic Crystals and Cubic Chiral Nets,", Phys. Rev. Lett. 106, 103902 (2011).

a) b) c) d)

88

STAFF POSTER SESSION

Board ANU Laser Physics Centre

1. Choi, Duk-Yong

Fabrication and characterization of silver-doped

chalcogenide planar waveguides for compact nonlinear

optical devices

2. Luther-Davies, Barry Generation of femtosecond pulses in the mid infra-red using

an optical parametric amplifier

3. Vu, Khu Hybrid As2S3 on Er Doped TeO2 Waveguide for Lossless

Nonlinear Optics

4. Wang, Rongping Chemical order in GexAsySe1-x-y glasses probed by high

resolution X-ray photoelectron Spectroscopy

5. Yang, Zhiyong Preparation of chalcogenide microspheres

Board UTS

6. Asatryan, Ara Local Density of States of Finite Girotropic Two Dimensional

Photonic Clusters Composed of Circular Cylinders

7. Dossou, Kokou Modal formulation for diffraction by absorbing photonic

crystal slabs

8. Dossou, Kokou

A three dimensional finite element method for the analysis of

plane wave diffraction by photonic crystals

Board University of Sydney

9. Atakaramians, Shaghik Existence of sub-wavelength modes in uniaxial metamaterial

clad fibers

10. Clark, Alex Quantum state translation in integrated optics

11. Domachuk, Peter Silk Photonics: Plasmonic Doping and Waveguides

12. Gutman, Nadav Stationary solutions to the nonlinear coupled-mode equations

near a quartic band edge

13. Hsu, Shih-Hsin Light transmission of the marine diatom Coscinodiscus wailesii

14. Hudson, Darren Mid-Infrared Laser Development: A Narrow-Linewidth,

Tunable, High Power Source at 3 mm

15. Husko, Chad Energy efficient all-optical signal processing: nanowires or

slow-light structures?

16. Judge, Alexander Hamiltonian approach to macroscopic electrodynamics in a

magnetoelectric medium

17. Kabakova, Irina Spontaneous symmetry breaking in nonlinear gratings with

local defects

18. Kabakova, Irina Complex fiber Bragg gratings for pulse stretching and gain

equalization in sub-cycle waveform synthesizer

19. Lee, Kwang Jo Characterization of Mid-infrared Photonic Crystal Cavities

20. Lee, Kwang Jo Low Refractive Index Biosensor Based on Composite Polymer

Fiber Directional Coupler

21. Pant, Ravi Tunable slow-and fast-light in a photonic chip via stimulated

Brillouin scattering

22. Schröder, Jochen Multi output-port spectral pulse-shaping for simulating

complex interferometric structures

23. Xiong, Chunle Slow-light Enhanced Correlated Photon-pair Generation

89

STAFF POSTER SESSION

Board ANU Nonlinear Physics Centre 24. Decker, Manuel Nanofabrication of Photonic Metamaterials

25. Helgert, Christian Spatial symmetry breaking in optical metamaterials

26. Maksymov, Ivan Broadband and Actively Tuneable Arrayed Plasmonic

Nanoantennas for Optical Communications and Sensing

27. Minovich, Aliaksandr Hot Spot in the Interference Pattern of Airy Surface Plasmons

28. Miroshnichenko, Andrey Optically induced antiferromagnetism in hybrid metamaterials

29. Mokkapati, Sudha Plasmonic light trapping for III-V quantum dot solar cells

30. Staude, Isabelle Fabrication of Advanced Photonic Nanoantennas

31. Sukhorukov, Andrey Classical optical simulation of bi-photon generation in

quadratic waveguide arrays

32. Sukhorukov, Andrey Observation of spontaneous parametric down conversion in

LiNbO3 waveguide array

Board RMIT

33. Bui, Lam All Optical Mixing for Microwave Photonic Instantaneous

Frequency Measurement

34. Nguyen, Thach Scattering Loss in Thin, Shallow-Ridge Silicon-on-Insulator

Waveguides

35. Steigerwald, Hendrik Domain engineering in LiNbO3 waveguides by strongly

absorbed UV light

36. Greentree, Andrew Waveguide approaches to engineered coupled quantum

systems

Board Macquarie University

37. Coutts, David Ultraviolet in the Ultrafast Lane

38. Delanty, Michael Harmonic Oscillator Superradiance in Integrated Photonics

39. Marshall, Graham Putting Even More Integration Into Integrated Quantum

Photonics

40. Palmer, Guido Direct femtosecond-writing of Yb:ZBLAN waveguide lasers

41. Vo, Thanh Phong Near-field probing of slow Bloch modes on photonic crystals

with a nanoantenna

Board Swinburne

42. Cao, Yaoyu Super-resolution photoinduction-inhibited nanofabrication

based on the two-photon absorption process

43. Jia, Baohua Functional three-dimensional nonlinear nanostructures in gold

ion nanocomposite

44. Nicoletti, Elisa Selective silver coating for nanoplasmonic structures

45. Ventura, Michael Optimisation of super-resolution photo induction-inhibited

nanolithography

46. Schröder-Turk, Gerd Circular Dichroism in Biological Photonic Crystals & Cubic Chiral

Nets

90

STAFF POSTER ABSTRACTS

Fabrication and characterization of silver-doped chalcogenide planar waveguides for

compact nonlinear optical devices

Duk-Yong Choi, Steve Madden, Rongping Wang, Barry Luther-Davies

Centre for Ultrahigh Bandwidth Devices & Optical Systems (CUDOS), Laser Physics Centre

Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200

Phone: +61 2 6125 9279


We doped a few percent of silver into chalcogenide waveguide in order to enhance its nonlinearity, and characterized its

nonlinear response by employing continuous wave four-wave mixing (CW-FWM). n2 of Ag-As2Se3 is 7-10 times larger

than that of As2S3, even though propagation loss of 2 micron wide guides is 10 times higher (~3 dB/cm). This higher n2,

however, would be beneficial for a compact device.

Chalcogenide glasses (ChGs) are emerging as an excellent platform for integrated nonlinear optical (NLO)

devices, owing to their high optical Kerr nonlinearities (n2) with a sub-picosecond response time as well as low

linear and nonlinear losses. Recently, around 2-4 times higher n2 has been reported by just adding a small

amount of silver in ChGs without increasing two-photon absorption [1]. Wet chemical etching was a common

technique in fabricating Ag-ChG waveguide because plasma etching of the material remains a rough surface

covered with Ag-residues. In this work we developed a novel approach to produce Ag photo-doped As2Se3 rib-

type waveguide using fluorine-based plasma and characterized its nonlinear response by employing continuous

wave four-wave mixing (CW-FWM). To avoid the etch residue issue we tried to dope silver on pre-patterned

As2Se3 waveguides; however, As2O3 (arsenolite) crystallites were formed on the surface as a result of oxidation of

As2Se3 during light illumination for photo-doping. Thin Al2O3 layer (around 1-5 nm) coated conformally on

As2Se3 guides prior to silver deposition could stop the photo-oxidation; furthermore, silver could diffuse in

through this thin layer. From the depth profiling of x-ray photoelectron spectroscope we confirmed that silver

content in a As2Se3 guide is uniform. FWM measurement indicated that n2 of Ag-As2Se3 is 7-10 times larger than

that of As2S3, even though propagation loss of 2 micron wide guides is 10 times higher (~3 dB/cm). Nonlinear

response of the guide is proportional to n2 and effective length of a device (Leff), which is determined by device

length and loss. In a short device, n2 contribution is dominant over Leff; consequently, Ag-As2Se3 would be an

efficient nonlinear optical material for a compact device.

[1] Keijiro Suzuki and Kazuhiko Ogusu, Opt. Express 13, 8634 (2005).

91


Generation of femtosecond pulses in the mid infra-red using an optical parametric

amplifier

Barry Luther-Davies


Laser Physics Centre, The Australian National University

Phone: 0261254255


Sub-picosecond coherent optical sources in the 3-4micron band are ideal for the generation of broadband supercontinuum

from chalcogenide nonlinear waveguides. Here I outline the design of an optical parametric amplifier (OPA) to generate

pulses around 300fsec in duration in the 2.3-4.5µm band.

Research into the use of optical parametric processes to generate tunable mid-IR light using crystals with a

second order nonlinearity has been underway for more than 40 years. The basic energy and momentum

conservation relations are written wp=ws+wi and kp=ks+ki where wp,s,i and kp,s,i are the angular frequencies and wave-

vectors of the interacting pump, signal and idler waves respectively. Two categories of device are commercially

available: optical parametric oscillators (OPOs) which place the nonlinear crystal in an optical resonator that

reflects signal or idler or both the generated waves so that the single pass parametric gain only needs to

overcome the resonator losses; and optical parametric generators (OPGs) where the crystals is used at high

intensities in a single pass with extreme gain. In both these devices the power grows from “noise” in the form of

spontaneous parametric fluorescence that thus serves the same role of spontaneous emission in a laser. As a

result it is often difficult to control the bandwidth and temporal (and spatial) coherence of the outputs from

OPAs and OPGs.

A third class of device which is not used very often is the optical parametric amplifier (OPA), which is a high

gain device similar to an OPG but includes an input at either the signal or idler wavelength along with the pump

that has sufficient intensity to dominate over the power produced by parametric fluorescence. Compared with

an OPG an OPA operates at slightly reduced gain, can produce transform-limited pulses if the pump is

transform limited, as well as near diffraction-limited beam profiles. By optimising the structure of the OPA good

conversion efficiency from pump to (signal +idler) of up to 60% can also be achieved. Currently a picosecond

OPA is the main MIR source operating in the Laser Physics Centre at ANU. This uses a 1064nm pump from a

mode-locked Nd:YVO4 laser to amplify seed pulses from a 30mW tunable diode laser plus EDFA in the 1530nm

band to produce amplified pulses at 1530nm and simultaneously transform-limited idler pulses at 3493nm with

a duration of ≈7ps. Whilst these pulses are capable of being used to generate a supercontinuum from a

chalcogenide nonlinear waveguide spanning from ≈2000 to >5000nm, the relatively long pulses correspond to a

large soliton number and an incoherent spectrum results. As a result shorter pulses are required. In this poster I

will describe a facility that we will seek funding support from LIEF in 2012 where we proposes to use ≈500fs

pulses from an Yb laser to pump a short PPLN OPA. Modeling taking group velocity dispersion and diffractive

effects into account suggest that around 25% conversion efficiency to (signal + idler) can be obtained with pulses

≈300fs in duration in the 3-4µm range with peak powers of 10-20kW. These pulses are short enough to lead to a

considerable improvement in the coherence of the supercontinuum spectrum.

92


Hybrid As2S3 on Er Doped TeO2 Waveguide for Lossless Nonlinear Optics

Khu Vu, Zhe (Kim) Jin, Kunlun Yan, Duk-Yong Choi, Xin Gai, Barry Luther-Davies, and Steve

Madden



Phone: 02 6125 4079


We have fabricated As2S3 on Erbium doped TeO2 single-mode planar rib waveguide. With peak absorption of at least 14dB

at 1532nm, this amplifier can result in gain of 7dB when pumped at 1480nm. This design can lead to zero-loss anomalous

dispersion waveguide for nonlinear optics.

Tellurium dioxide offers a number of advantages as an efficient host for Erbium doped waveguide amplifiers

(EDWAs) over other materials because of its high refractive index (larger emission cross section and more

compact devices), large emission bandwidth, and high Erbium solubility as has been demonstrated in Tellurite

glass and fiber amplifiers [1-2]. We recently demonstrated high gain Er doped TeO2 waveguide amplifier with

gain of 2.8dB/cm [3]. Arsenic trisulphide has been successfully used for a number of breakthrough experiments

in nonlinear optics and telecommunication [4]. This work attempts to combine the two materials into a zero-loss

anomalous dispersion waveguide for non-linear optical signal processing. The Er doped TeO2 layer provides

gain to compensate for the propagation loss of the As2S3 above. The As2S3 layer provides the high nonlinearity.

The Er doped TeO2 thin film was fabricated by reactive co-sputtering of pure Te and Er targets into an Ar+O2

plasma. The Er concentration was ~1%. The lifetime of the 1.55m decay was 1.6ms. The layer has the thickness

of 387nm with refractive index at 1550nm of 2.081nm. The As2S3 layer was deposited by thermal evaporation to

the thickness of 350nm. The rip waveguide was achieved after etching of the As2S3 layer to its total thickness (Fig

1a). An IPG cladding was spin coated on top. A chip with length of 65mm was achieved after diamond tip

scribing.

Waveguides with width of 2.0m provide a mode area of 2m2 and the overlap of 28% and 37% to the Er:TeO2

layer for TE0 and TM0, respectively (Fig 1b). The loss spectrum from 900nm to 1700nm shows that there is

significant Er absorption as expected (Fig 1c) on top of propagation loss of 0.5dB/cm The peak absorption is

more than 14dB at 1532nm. With 1480nm pumping, which can provide 75% inversion of the Er population, the

gain is expected to be 7dB/cm. This means that the total propagation loss is fully compensated by the gain and

lossless waveguide can be achieved.

a) b) c)

Fig. 1. Design (a), mode profile (TE0) (b) and loss spectrum of the As2S3 on Er doped TeO2 waveguide (6cm long) (c)

1. C. E. Chryssou, F. Di Pasquale, and C. W. Pitt, "Er3+-doped channel optical waveguide amplifiers for WDM systems: A comparison of

tellurite, alumina and Al/P silicate materials," IEEE J. Sel. Top. Quantum Electron. 6, 114-121 (2000).

2. A. Mori, "Tellurite-based fibers and their applications to optical communication networks," J. Ceram. Soc. Jpn. 116, 1040-1051 (2008).

3. K. Vu, S. Madden “Tellurium dioxide Erbium doped planar rib waveguide amplifiers with net gain and 2.8dB/cm internal gain”, Op. Exp.

18, 18 (2010)

4. B. Eggeston, B Luther-Davies and K Richardson, “Chalcogenide photonics”, Nature Photincs, 5 (2011)

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-20

-15

-10

-5

0

900 1100 1300 1500 1700

Wavelength (nm)

Lo

ss (

dB

)

Scattering Fitting

Measured loss

IPC cladding

Thermal Oxide on

Silicon wafer

Er-doped TeO2

As2S3

380nm

350nm

2000nm

Er abs. IPG abs.

93


Chemical order in GexAsySe1-x-y glasses probed by high resolution X-ray photoelectron

Spectroscopy

R. P. Wang, D. Y. Choi, S. Madden, A. Smith and Barry Luther-Davies



A.C.Miller and H.Jain

Department of Materials Science and Engineering, Lehigh University,

5 East Packer Avenue, Bethlehem, Pennsylvania 18015-3195, USA

Phone: 02 6125 1591


We have measured high-resolution x-ray photoelectron spectra (XPS) of GexAsySe1-x-y glasses with a MCN

from 2.2 to 2.78. The valence band spectra showed that a number of Se-Se-Se trimers can be found in Se-rich

samples, whilst multiband features induced by phase separation can be observed in extremely Se-poor samples.

When the Ge, As, and Se 3d spectra were decomposed into 4, 3 and 2 doublets, which correspond respectively to

different chemical surroundings, the perfect AsSe3/2 pyramidal and Ge4/2 tetrahedral structures in Se-rich

samples gradually evolved into defect structures including As-As and Ge-Ge homopolar bonds with increasing

Ge and As concentrations. Two transition-like features were found at MCN=2.5 and 2.64-2.72 that correspond

firstly to the disappearance of Se-chains in the glass network, and subsequently destruction of the perfect

AsSe3/2 pyramidal and Ge4/2 tetrahedral structures, respectively [1,2].

Fig. 1 (left) The valence band spectra of GexAsySe1-x-y glasses. The dotted lines with the arrows labeled the peaks are for clarification.

Fig. 2 (right) The relative ratio of the integrated areas of each doublets in (a) Se, (b) As and (c) Ge, respectively. The dotted lines with the

arrows labeled the positions of two transition-like behaviors are for clarification.

References 1. R.P.Wang, A.Smith, P.Amrita, D.Y.Choi, B.Luther-Davies, Journal of Applied Physics 106, 043520(2009).

2. R.P.Wang, A.Smith, B.Luther-Davies, Journal of Applied Physics 109, 023517 (2011).

2.2 2.3 2.4 2.5 2.6 2.7 2.80

50

100 (a)

Mean Coordination Number

Ge-Se-Ge

Ge-Se-Se

Se-Se-Se

0

50

100(b)

Rat

io

2As-As-Se

As-As-2Se

As-3Se

0

50

100(c)

3Ge-Ge-Se

2Ge-Ge-2Se

Ge-Ge-3Se

Ge-4Se

0 5 10 15 20 25

Binding Energy (eV)

Ge5As

30Se

65

Ge5As

20Se

75

Ge5As

10Se

85

Ge5As

10Se

85

Ge15

As10

Se75

Ge12.5

As25

Se62.5

Ge15

As25

Se60

Ge24

As24

Se52

Ge15

As34

Se51

Ge33

As12

Se55

Rela

tiv

e I

nte

nsi

ty (

arb

.un

its.

)

94


Preparation of chalcogenide microspheres

Zhiyong Yang, Barry Luther-Davies

Centre for Ultrahigh bandwidth Devices for Optical Systems, Laser Physics Centre, Australian

National University

Guangming Tao, Ayman F. Abouraddy

CREOL, The College of Optics & Photonics, University of Central Florida, Orlando, Florida 32816,

Phone: 02-61254611


As-S chalcogenide microspheres were prepared by thermally treating multimaterial fibers which consist of polymer

claddings and chalcogenide glass cores. The size of the spheres can be accurately controlled and the surfaces are highly

smooth. Using this technique, large quantities of microspheres with relatively uniform diameter can be prepared each time.

Optical microcavity sensing [1] has been demonstrated as a powerful method for molecular detection because of

the enhanced interaction of resonance lights with molecules. In this respect, chalcogenide microspheres have

advantages due to their strong light confinement and excellent transmitting property in the molecular

fingerprint region of the spectrum between 2 and 20μm. Here we report a special technique suitable for mass

production of high quality chalcogenide microspheres.

Here we use the fabrication of As35S65 microspheres to demonstrate this technique. First, multimaterial fibers

consisting of As35S65 glass core and thermally compatible polymer cladding (polyethersulfone, PES) were drawn,

and then the multimaterial fibers were thermally treated at an appropriate temperature. As35S65 microspheres

formed in the PES cladding during the heat treatment due to the instability of cylindrical threads of viscous

liquids under capillary forces. The PES cladding was finally dissolved into a solvent dimethylacetamide

(DMAC) to obtain the microspheres.

To fabricate the multimaterial fibers [2], a Ф40mmx10mm preform consisting of a 10mm As35S65 glass core

surrounded by PES cladding was prepared and thermally drawn into fibers with a diameter around 1mm (the

core size was about 250μm). The As35S65 core diameter was then reduced to 10-20μm using the stack-and-draw

approach, which yielded high-density microwires embedded in the PES fibers. The finally obtained fibers

contained 62 As35S65 cores with the diameter of 10-20μm. The initial 10-mm-diameter As35S65 rod was prepared

by melt-quenching method, and the cladding was formed by rolling a 75μm thick PES film followed by thermal

consolidation. The preform was then drawn into fibers at around 360 oC.

Fig.1 shows the spheres obtained after the heat treatment. There are two groups of As35S65 spheres forming along

the fiber core (Fig.1(a)). One group has a diameter close to that of the fiber core. The other group has a diameter

of about 1/20-1/10 of the core diameter. These smaller spheres are formed between two bigger spheres. After

dissolving the polymer cladding, a large quantity of spheres can be collected (Fig.1(b)). The spheres do not show

clear deformation and the surfaces look quite smooth (Fig.1 (c), (d) and (e)). Chalcogenide microspheres

prepared through this approach are expected to possess relatively high optical quality (e.g. high Q factor).

Fig. 1: (a) Optical microscopic image of As35S65 microspheres in polymer after annealing the multimaterial fiber at 3000C for

3h; (b) SEM image of spheres after dissolving the polymer in DMAC solvent; (c) optical microscopic image of a single sphere

with a diameter of 20 μm; (d) and (e) SEM images of a single sphere with a diameter of 700nm and 16μm, respectively.

[1] T. Yoshie, L. Tang, S.Y. Su, “Optical Microcavity: sensing down to single molecules and atoms,” Sensors 11, 1972-1991 (2011)

[2] J. J. Kaufman, G. Tao, S. Shabahang, D.S. Deng, Y. Fink, A.F. Abouraddy, “Thermal drawing of high-density macroscopic arrays of well-

ordered sub-5nm-diameter nanowires,” Nano Letters 11, 4768-4773 (2011)

95


Local Density of States of Finite Girotropic Two Dimensional Photonic Clusters Composed

of Circular Cylinders

A.A. Asatryan, and L.C. Botten


Department of Mathematical Sciences, University Of Technology Sydney

Phone: (02) 9514-2259


We have constructed a two dimensional Green’s tensor for finite two dimensional giro-electric or giro-magnetic photonic

clusters composed of cylinders with circular cross-section and calculated the local density of states (LDOS) in such clusters.

In these clusters the time reversal symmetry is broken which allows the construction of nonreciprocal optical circuits. On an

example of a cluster that supports one way edge modes we have calculate the LDOS map and revealed its properties.

One of the main shortcomings of waveguides embedded in photonic crystals is backscattering losses at the

interfaces of different interconnects. To overcome this shortcoming, giro-electric and giro-magnetic materials

have been proposed. In such structures the time reversal symmetry is broken, which allows one way

waveguiding [1]. Backscattering in such structures is forbidden topologically. Apart from the waveguiding

properties of such structures it is also important to know the radiation characteristics of embedded sources.

These characteristics are determined by the LDOS of the structure, which can be calculated from the trace of the

imaginary part of the Green’s tensor

Here we have generalized our initial multipole treatment [2] to construct the Green’s tensor for girotropic (giro-

electric or giro-magnetic) photonic clusters with material parameters given by

=

, =

.

Fig. 1 The geometry of the structures which supports the one way edge mode [3] (left panel). The red cylinders represent the

giro-electric cylinders located in the honeycomb lattice ; the LDOS distribution at the one-way edge frequency (right panel).

In Fig.1 (right panel) we plot the LDOS distribution for cluster with 220 cylinders with embedded giro-electric

inclusions (red cylinders in Fig.1). The radii of the air cylinders are a=0.35d and the cylinders are embedded in

media with the dielectric constant =16. The parameters for the giro-electric cylinders are xx = 16 and xy = 1 and

radii a=0.48d, where d is the period of the structure. The infinite hexagonal structure has full band gap at the

wavelengths range [3.39-5.21]. The giro-electric cylinders form a honeycomb lattice with the lattice constant

d’=6d. The LDOS is plotted for a wavelength of 4.48d which corresponds to the one-way edge mode wavelength.

The LDOS shows the 10 fold enhancement of the radiation properties of sources located in the waveguide. The

enhancement of the LDOS is not uniform along the waveguide and reduces to the free space value at the centre.

References [1] F.D.M. Haldane, and S. Raghu, “Possible realization of directional optical waveguides in photonic crystals with broken time-reversal symmetry”,

Phys. Rev. Lett. 100, 013904 (2008) .

[2] A.A. Asatryan, K. Busch, R.C. McPhedran, L.C. Botten, C.M. de Sterke, and N.A. Nicorovici “Two-dimensional Green’s function and local

density of states in photonic crystals consisting of a finite number of cylinders of infinite length ”, Phys. Rev. E 63, 046612 (2001) .

[3] K. Fang, Z. Yu, S. Fan “Microscopic theory of photonic one-way edge mode ”, Phys. Rev. B 84, 075477 (2011) .

96


Modal formulation for diffraction by absorbing photonic crystal slabs

Kokou B. Dossou1*, Lindsay C. Botten1, Ara A. Asatryan1, Björn P.C. Sturmberg2, Michael A. Byrne1,

Christopher G. Poulton1, Ross C. McPhedran2, and C. Martijn de Sterke2

Centre for Ultrahigh bandwidth Devices for Optical Systems 1School of Mathematical Sciences, University of Technology, Sydney

2School of Physics, University of Sydney *Phone: 61-2-9514-2145 Email: [email protected]

A finite element-based modal formulation of diffraction of a plane wave by an absorbing photonic crystal slab of arbitrary

geometry is developed for photovoltaic applications. The semi-analytic approach allows efficient and accurate calculation of

the absorption of an array with a complex unit cell. This approach gives direct physical insight into the absorption

mechanism in such structures, which can be used to enhance the absorption.

A new and increasingly important application of photonic crystal structures is in the field of photovoltaics. The

conversion efficiency of photovoltaic cells can be increased by using structured materials [1], with one of the

most promising designs involving the use of silicon nanowire (SiNW) arrays [2]. In most cases, the

characterization of the absorption properties of such structures entails general numerical techniques such as the

finite element method, plane wave expansions, or the finite-difference time-domain method. Such purely

numerical approaches require substantial computational resources and provide little or no insight into the

physical mechanism of absorption in SiNW arrays. Accordingly, we have sought to derive a semi-analytic

method, which is optimized to this calculation, allowing the efficient exploration of the parameter space needed

to optimize the geometry for absorption enhancement, and which is able to provide insight into the physics of

the absorption process. The SiNW array is a square lattice of nanowires located in free space and its geometry is

depicted in Fig. 1(a). The structure can be modeled as a Fabry-Perot interferometer. The fields in the semi-

infinite media above and below the cylinder are represented by plane wave expansions while the field within

the array of cylinders is represented by an expansion in term of the Bloch modes E(x,y,z)=E(x,y) exp(i z) of the

lattice. The field expansions inside the slab are matched to those outside by the technique of projection onto a

basis of functions. This projection uses the adjoints of the Bloch modes, because of the presence of absorption in

the silicon rods. The transmission and reflection matrices for the entire structure are given by the relations

T = T21 P (I − R21 P R21P)−1 T12 , (1)

R = R12 + T21 P (I − R21 P R21P)−1R21PT12,

which are matrix generalisations of the transmission and reflection coefficients of a Fabry-Perot interferometer.

The absorption can be obtained from the energy conservation relation A=1-T-R.

(a) (b) (c)

References [1] L. Tsakalakos, “Nanostructures for photovoltaics,” Materials Science and Engineering R, 62, 175–189 (2008).

[2] B. C. P. Sturmberg, K. B. Dossou, L. C. Botten, A. A. Asatryan, C. G. Poulton, C. M. de Sterke, and R. C. McPhedran, “Modal analysis of

enhanced absorption in silicon nanowire arrays,” Opt. Express, vol. 19, A1067–A1081 (2011).

Fig. 1: Fig. 1: (a) Illustration of the SiNW arrays. (b) The dotted black, thin blue and thick red curves are the absorption

spectrum at normal incidence, respectively, for a dilute SiNW array (with silicon fill fraction 3.1% and nanowires height

2.33μm), for a homogeneo s slab of eq al thickness and of a homogeneous slab comprising equal volume of silicon. (c)

Contour plot of the absorptance as a function of the wavelength and the nanowires height.

97


A three dimensional finite element method for the analysis of plane wave diffraction by

photonic crystals

Kokou B. Dossou* and Lindsay C. Botten


School of Mathematical Sciences, University of Technology, Sydney *Phone: 61-2-9514-2145 Email: [email protected]

A three-dimensional finite element method (FEM) for the analysis of plane wave diffraction by a photonic crystal slab is

described and implemented. A scattering matrix formalism based on the FEM allows the efficient treatment of light

reflection and transmission by multilayer photonic structures, and the computation of Bloch modes of three-dimensional

arrays. Numerical simulations show the accuracy and flexibility of the FEM.

The analysis of light scattering by photonic crystals or metamaterials is critical to many contemporary

applications in photonics. The light propagation can be modelled by the vectorial wave equation

1 2( ) . E E 0

The classic electromagnetic theory [1] of plane wave diffraction by periodic structures has provided the

mathematical foundation for a large number of numerical methods for diffraction gratings, many of which were

restricted to one-dimension or two-dimension models of photonic crystals under the assumption that the device

geometry can be approximately simplified to a structure which extends indefinitely in one or two dimensions

and is invariant in these dimensions. Since actual photonic crystal devices are three dimensional (3D) objects of

finite size, the accurate modeling of these devices requires 3D numerical tools. Indeed, there is a great research

interest in the development of numerical approaches for solving 3D scattering problems and we have developed

an FEM which offers the flexibility to accurately model problems with arbitrary geometry. Multilayered

structures are a prevalent geometry for photonic crystal devices. However, the computational resource required

by the direct application of numerical techniques, such as the FEM, to these elements becomes quickly

prohibitive as the number a layers increases. In order to address this issue, the FEM incorporates the scattering

matrix formalism [2]. Interestingly, the Bloch modes of periodic 3D photonic elements can be computed from the

scattering matrices. We have applied the FEM to the analysis of photonic elements such as woodpile structures

(see Fig. 1) and checkerboard gratings. The numerical results show that our FEM is an efficient and accurate

method for modeling the light scattering by 3D photonic elements. Thus our approach can play an important

role in the development of semi-analytic Bloch mode approaches for 3D photonic crystal and metamaterial

structures.

(a) (b) (c)

Fig. 1: (a) Schematics of a woodpile photonic crystal. (b) Plane wave reflectance curves of a 32-layered woodpile structure. (c)

Dispersion curves of the woodpile.

References [1] R. Petit (Ed.), “Electromagnetic theory of gratings”, vol. 22 of Topics in Current Physics, Springer-Verlag, New York, 1980.

[2] K. Dossou, M. A. Byrne, and L. C. Botten, "Finite element computation of grating scattering matrices and application to photonic crystal

band calculations", J. Comput. Phys., vol. 219, no. 1, pp. 120-143 (2006).

98


Existence of sub-wavelength modes in uniaxial metamaterial clad fibers

Shaghik Atakaramians, Alexander Argyros, Simon C. Fleming, and Boris T. Kuhlmey


Institute of Photonics and Optical Science, School of Physics, University of Sydney

Phone: 02-93514019


We discuss the conditions in which guided and plasmonic modes exist in an air-core fiber with anisotropic, uniaxal

metamaterial cladding. We illustrate that these hollow-core fibers can offer sub-wavelength guidance, with diameters up to

ten times smaller than the operating wavelengths.

Metamaterial (MTM)-based waveguides such as single/multilayered MTM slabs [1,2], MTM-core fibers [3],

MTM-clad fibers [4] offer unusual phenomena such as backward waves, simultaneous propagation of backward

and forward wave, bifurcation points (where backward and forward waves branch off), fast and slow waves,

and power circulation [1-5]. The MTM fibers investigated so far have isotropic core and cladding. In realistic

implementation, MTM structures are not isotropic, in particular for longitudinally invariant “drawn

metamaterial” fibres [6]. We find that for an uniaxial ( ) MTM clad air-hole fibre,

guided modes can exist depending on the relative signs of the different components or μ and ε as summarized

in Fig. 1(a). Depending on parameters, both conventional waveguide (CW) modes as well as surface plasmon

polariton modes (SPP) can be supported. We investigate the existence and dispersion of modes using an

experimentally motivated model for the longitudinal (Fig 1(b)) or transverse permittivity and permeability (Fig

1(c)). The model is based on resonant magnetic and plasmonic electric responses, covers both positive and

negative values of the permittivity and permeability, and is widely used in theoretical MTM studies [1,5].

Fig. 1: Uniaxial MTM clad air-hole circular waveguide: (a) Mode existing condition. (b) Dispersion of TE mode when the

longitudinal relative permittivity and permeability of the MTM clad follow the curves in Ref [5] while

. (c) Dispersion of HE mode when the transverse relative permittivity and permeability of the MTM clad follow

the curves in Ref [5], and . The solid horizontal line represents the boundary of radiation and guided

modes. The dashed horizontal line represents the core refractive index.

Figure 1(b) shows that dispersive transverse material values provide sub-wavelength confinement of a TE mode,

with a core 5 times smaller than the shortest operating wavelength. Only forward propagating modes are

guided, transitioning smoothly from CW to SPP modes. Figure 1(c) shows that dispersive longitudinal material

values leads to sub-wavelength confinement with air-holes dimension 50 times smaller than the shortest

operating wavelength, where the fundamental mode is HE or EH. A combination of forward (CW) and

backward (CW & SPP) modes are excited. Note that the hybrid dispersion curves approach the radiation and

guided modes boundary line with a negative slope, i.e. if they start with forward propagating mode, the curve

encounters a bifurcation at which there is no power flow (trapped modes).

1. I.V. Shadrivov, A.A. Sukhorukov and Y.S. Kivshar, Phys. Rev. E 67 57602A (2003) for example.

2. K.L. Tsakmakidid, C. Hermann, A. Klaedtke,C. Jamois and O. Hess, Phys. Rev. B 73 085104 (2006) for example.

3. A.V. Novitsky, and L.M. Barkovsky, J. Opt. A: Pure Appl. Opt. 7 S51 (2005) for example.

4. K.Y. Kim, J-H Lee, Y.K. Cho and H-S Tae, Opt. Express 13 3653 (2005).

5. K.Y. Kim, J. Opt. A: Pure Appl. Opt. 9 1062–1069, (2007).

6. A. Tuniz et al., Opt. Express 19, 16480 (2011).

+ + – –

– – + +

+ ± + ±

– ± – ±

(a) (b)

(c)

99


Quantum state translation in integrated optics

Alex S. Clark, Matthew Collins, Chunle Xiong and Benjamin J. Eggleton



Phone: 02 935 14044


In this paper we discuss the concept of quantum state translation, where a quantum state encoded on a single photon of one

wavelength is translated to a photon of another wavelength. We propose methods to generate and translate photons in

integrated nonlinear waveguides using four-wave mixing and a preliminary experiment using dispersion shifted fiber.

The controlled generation and manipulation of different photonic states is integral to many future quantum

technologies. To achieve wavelength flexibility we consider the conversion of single photons from one

wavelength to another whilst leaving all other quantum properties of those photons unaltered, termed quantum

state translation (QST). Large translations of wavelength will see applications in up-converting detectors [1] and

interfacing with visible wavelength sources, but applications over short ranges are equally important [2]. The

ability to erase distinguishability between photons allows their use in quantum logic operations [3] and an

exciting theoretical application of QST is the possibility to interfere photons of different wavelengths [4].

Figure 1. - Experimental setup to perform QST. AWG – arrayed waveguide grating, PC – polarization

controller, EDFA – erbium doped fiber amplifier, PM – power meter, WDM – wavelength division multiplexing

coupler, DSF – dispersion shifted fiber, SPD – single photon detector, FPGA – field programmable gate array.

The proposed setup to perform QST in a guided nonlinear medium is shown in Fig. 1. Photons are generated in

a silicon photonic crystal waveguide through spontaneous four-wave mixing [5] and then separated using an

AWG, where we select signal and idler channels corresponding to at 1545 nm and 1555 nm respectively. The

signal photon is filtered and detected using a SPD while the idler photon is coupled to a 1 km length of DSF.

Two CW lasers separated, by the same energy as the signal and idler photons, are combined into the same

output of a 50:50 coupler before also being coupled to the DSF using a WDM. In the DSF a photon from one

pump laser and the idler photon are annihilated and photons at the signal and other pump wavelengths are

created through stimulated four-wave mixing. The output passes through a tunable filter and is detected using

another SPD. Coincidences are then measured between the two detectors using a field programmable gate array

(FPGA) and a computer for different output filter detuning. When the filter is positioned at the wavelength of

the signal photons from the original source, any photons detected should be indistinguishable from each other

and one can perform a quantum interference experiment to further analyse the success of the QST process.

1. A.P. Vandevender et. al., J. Mod. Opt. 51, 1433 (2004) and M.A. Albota et. al., Opt. Lett. 29, 1449 (2004) for example.

2. H.J. McGuinness, M.G. Raymer, C.J. McKinstrie and S. Radic, Phys. Rev. Lett. 105, 093604 (2010).

3. H. Takesue, Phys. Rev. Lett 101, 173901 (2008).

4. H.J. McGuinness, M.G. Raymer and C.J. McKinstrie, Optics Express 19, 17876 – 17907 (2011).

5. C. Xiong et. al., Opt. Lett. 36, 3413 (2011).

100


Silk Photonics: Plasmonic Doping and Waveguides

Peter Domachuk and Rebecca Lodin



Phone: +61-2-9351 3953


Silk fibroin, the structural protein in natural silk fibre, is re-spun as a novel optical material. It is highly transparent,

strong, biocompatible, bio-dopable, and pattern-able on the micro- and nano-scale. We demonstrate the fabrication of silk

waveguides and silk films doped with gold nano-particles. Both of these may lead to future biomedical applications in

sensing and therapy, respectively.

101


Stationary solutions to the nonlinear coupled-mode equations near a quartic band edge

Nadav Gutman and Martijn de Sterke


The School of Physics, The University of Sydney


We present stationary numerical solutions to the nonlinear coupled-mode equations near a quartic band edge. We

find that the required input power to change transmission nonlinearly from a low to a high value is an order of magnitude

lower than that required close to a regular quartic band edge. This low power originates from the high field intensity

that emerges from the constructive interference between two closely degenerate evanescent modes.

Periodic structures have frequency stop bands where only evanescently decaying modes exist, thus leading to

low transmission. When using high power light, nonlinear effects enable transmission, a phenomenon closely

related to gap solitons. These effects were previously investigated, both theoretically and experimentally, in fiber

gratings. To the best of our knowledge all 1D systems which have been investigated thus far exhibit a quadratic

dispersion relation near the band edge, i.e., , where and are the frequency and wavenumber

detuning from the band edge, respectively. In this work we investigate systems that have quartic band edge

dependency of the form [Fig. 1(a) red], and compare these to regular quadratic systems [Fig. 1(a) blue].

Sukhorukov et al. [1] showed that a quartic can be created in a 2-mode optical fiber, a system which is described

by four coupled-mode equations. We show that nonlinear coupled-mode equations of this system contains three

different coefficients

(1)

Where the are the transverse profile of the two mode , and the nonlinear response of the fiber.

For a fiber supporting the two first symmetric modes, LP01 and LP02, we find . The stationary

solutions for the four nonlinear couple-mode equations were found by backward integration of the field for a

given output flux.

Fig. 1: Comparison between quadratic (blue) and quartic (red) fiber grating design in a silica fiber for 1550 nm wavelength

and 53cm long. (a) Frequency vs. wavelength. (b) Transmission vs. the incoming intensity. (c) Normalized field intensity

inside the fiber in for low power inputs.

The solutions are presented in Fig. 1(b) (red) as the transmission versus the input power, together with the

solutions for the regular quadratic (blue) for comparison. This figure shows that the required input power for

unity transmission is of order of magnitude less in the quartic system than in the quadratic system. This for a

fiber with the same length, low power transmission, and detuning from the band edge [dashed line in Fig. 1(a)].

A hint of the reason for this can be found in the low intensity field profile inside the fiber, see Fig. 1(c). Due to

the degeneracy between two evanescent modes of the quartic system a large field intensity exist inside the fiber

which enhances the nonlinear interaction [2].

[1]. A.A. Sukhorukov, et. al., " Slow light with flat or offset band edges in few-mode fiber with two gratings", Opt. Express 15, 17954 (2007).

[2]. N. Gutman, et. al., “Degenerate band edges in optical fiber with multiple grating: efficient coupling to slow light,” Opt. Lett. 36, 3257–

3259 (2011).

-5 0 5-5

0

5

Fre

q (

MH

z)

Wavevector (m-1

)

(a)

100

101

102

0

0.5

1

Input NL

|E|2

Tra

nsm

issio

n (d)

-0.4 -0.2 00

1

2

3

4

Position (m)

Am

p |E

|2/|E

in|2 (c)


102


Light transmission of the marine diatom Coscinodiscus wailesii

Shih-Hsin Hsu, Camille Paoletti, Moacir Torres*, Raymond J. Ritchie*,

Anthony W. D. Larkum*, and Christian Grillet



*School of Biological Sciences, University of Sydney

Phone: +61-2-93517697


Light transmission behavior of a centric diatom species Coscinodiscus wailesii is reported. The 3-dimensional intensity

distributions of transmitted light through individual valves of the diatom in air and water were measured. At a certain

distance from the valve, light is concentrated into a spot on the optical axis and the distances are wavelength-dependent.

Diatoms are unicellular microalgae and renowned for their peculiar silica cell walls (frustules) which possess

regular arrays of micro- to nanometer pores. Because they contribute a large portion of photosynthesis in oceans,

thorough studies of frustules’ optical properties are of great value. Here, we report an optical microscopy

investigation of light transmission behavior of a centric diatom species Coscinodiscus wailesii. The 3-D transmitted

intensity distributions of broadband and monochromatic light through individual valves of the diatom in air as

well as in water were measured by acquiring transmission images at varying objective-sample distances. For

several valves under investigation, at a certain distance from the valve, light intensities close to the optical axis

are relatively higher than those in the surrounds, which is similar to the effect of lens focusing. At a longer

distance, light intensities display ring-shaped profiles. The distances showing these concentrated profiles are

wavelength-dependent. However, for some valves, the above behavior was extremely weak or indiscernible.

Possible causes of this discrepancy between valves will be discussed. These results may offer insight into the

understanding of biological functions of diatom frustules’ structures and inspire optical biomimetic applications.

Fig. 1: SEM images of diatom’s

valves (scale bars from left to

right: 100, 10, 1 m).

Fig. 2: Transmission optical images taken at the focal plane (a) and positions showing light concentration at the centre (b) and

into a ring (c); wavelength dependence of light concentration characteristics (d).

0 168 m 296 m

450 500 550 600 650

150

200

250

300

valve 1

valve 2

valve 3

Dis

tan

ce

fro

m f

oca

l p

lan

e (m

)

Wavelength (nm)(a) (b) (c) (d)

103


Mid-Infrared Laser Development:

A Narrow-Linewidth, Tunable, High Power Source at 3 m

Darren D. Hudson, Eric C. Magi, Benjamin J. Eggleton, and Stuart D. Jackson


Physics Department, University of Sydney

Phone: +61 02 9351 7697


We demonstrate a 1 Watt average power Holmium/Praseodymium co-doped Fluoride glass fiber laser pumped via solid state

diodes operating at 1150nm. An intra-cavity diffraction grating mounted in the Littrow feedback configuration narrows the

linewidth to less than 0.5 nm and provides tunability from 2825-2900 nm. By achieving high-quality cleaves of the D-

shaped double clad Fluoride fiber we were able to demonstrate a record slope efficiency of 28.5 %.

Mid-infrared photonics is a fast-growing field within integrated optics. To support this growth, a wide range of

pump and probe sources are required to develop the integrated optical components that are necessary for

medicine, defence and astronomy. Rare-earth doped fiber lasers [1], in particular, are well suited to provide high

power, large tuning range, and high beam quality. In this project, the addition of Pr3+ ions serves to densitisize

the lower laser level of the Ho3+ ions, thus enhancing the slope efficiency. This co-doping allows us to

demonstrate a record slope-efficiency of 28.5% for 3 m fiber laser systems [2].

Light from the 1150 nm pump diodes was combined using a polarizing cube and injected into the double-clad

Ho/Pr fiber (see Fig. 1(a)). The core of the double clad fluoride fibre had Ho3+ and Pr3+ ion concentrations of

30,000 ppm molar and 2500 ppm molar, respectively. Tuning of the 5I6-5I7 transition in Ho3+, which has a peak at

2860 nm, was carried out using intra-cavity diffraction grating feedback. Two fiber lengths were tested (see Fig

1(b)) and as expected the longer gain fiber exhibited higher gain but with reduced tuning range due to parasitic

lasing off the end facets that occurs when the feedback from the grating drops below the fiber tip Fresnel

reflection. The laser tuning range using the 6.3 m was > 30 nm with over 1 W average power output, while the

2.3 m fiber system tuned over 75 nm with > 200 mW average power. This source represents a valuable lab tool

for testing and probing devices operating in the mid-IR wavelength range.

Fig. 1: (a) Cavity design for the Ho/Pr fiber laser. The diffraction grating feedback allows for a narrow, tunable laser line and

the co-doped Ho/Pr fiber yields high efficiency. The 1150 nm light is focused into the double-clad gain fiber via a x10

(NA=0.25) microscope objective. (b) Output spectrum for 2 fiber lengths: 6.3 m (circles), 2.3 m (squares).

1. S. D. Jackson, “Single-transverse-mode 2.5-W holmium-doped fluoride fibre laser operating at 2.86 m”, Opt. Lett. 29, 334 (2004). 2. D. Hudson, E. Magi, L. Gomes, S.Jackson, “1W diode-pumped tunable Ho3+-Pr3+ doped fluoride glass fibre laser,” Elec. Lett. 47, 985 (2011).

104


Energy efficient all-optical signal processing: nanowires or slow-light structures?

Chad Husko and Benjamin J. Eggleton

Centre for Ultrahigh bandwidth Devices for Optical Systems, School of Physics, University of

Sydney, Phone: +61 2 9351 3953, Email: [email protected]

We compare the energy performance of nanowires to slow-light photonic crystals in chip-scale nonlinear optical processes.

A deep understanding of the advantages and disadvantages of these widely used platforms is critical in the development of

integrated photonic circuits. We outline regimes where each platform is more energy efficient. These results suggest a road

map towards energy efficient silicon photonics.

We analyze and compare the energy performance of nanowires and slow-light photonic crystals in chip-scale

nonlinear optical processes. The mature silicon platform presents a tremendous opportunity to develop hybrid

electronic/optoelectronic circuits [1]. These integrated devices offer the promise of unprecedented functionalities

at ultralow energies in a cost-effective manner. To this end, wavelength scale waveguides known as 'nanowires'

and slow-light photonic crystals are under intense investigation as key components in the silicon photonics

paradigm. From device footprint, fabrication control, and energy consumption, the geometries of nanowires and

photonic crystals present distinct advantages and challenges. Slow-light structures, with their enhanced light-

matter interaction, are often heralded as a path towards sub-millimeter, energy efficient, silicon photonics. Light

travelling at a reduced group velocity, typically greater than c/20 in photonic crystals, causes a buildup of

localized light intensity much larger than traditional ‘fast-light’ waveguides, thus allowing nonlinear effects at

reduced input energy [2]. Nonlinear operations such as self-phase modulation, four-wave mixing, and all-optical

switching in devices just hundreds of microns long have been demonstrated employing slow-light [2,3].

Fig. 1: (a) Nanowire waveguides with typical cross-section of ~ 300x500 nm (height x width). These waveguides can be bent

into tight spirals to increase effective length on a short chip at the cost of increased footprint area. (b) Photonic crystal

waveguide, with mode dimensions ~220x700 nm. A minimum number of periods to contain slow-light modes make the

footprint slightly larger. (c) Contour plot comparing the conversion efficiency of FWM in PhCWGs and nanowires limited to

5 mm in length at probe detuning of =3 nm. Red (Blue) values indicate an advantage to PhCs (nanowires) with the black

line indicating break-even.

The instantaneous four-wave mixing (FWM) process is of particular interest due to its versatility in performing

all-optical signal processing functions. In recent years FWM experiments in parametric wavelength conversion,

switching, logic, parametric gain, time-lenses, and all-optical demultiplexing have been demonstrated in these

two platforms [4-6]. However, it is not obvious from current experimental progress which of these media offers

a clear advantage. Fig. 1 shows the first comprehensive quantitative energy analysis of nonlinear effects in these

two common waveguide geometries. We incorporate real experimental conditions, including slow-light scaling

of both nonlinear and linear optical processes, in addition to operation bandwidth. Our results delineate regimes

where nanowires and slow-light photonic crystals exhibit salient advantages and limitations. We address both

(1) energy efficiency and (2) compactness of the devices, as well as the impact of anticipated improvements in

fabrication technology. These results suggest a road map towards energy efficient silicon photonics.

References [1] R. Soref, IEEE J. Selected Topics in QM Electronics 12, 1678 (2006). [2] T. Baba, Nature Photonics 2, 465 (2008).

[3] J. F. McMillan et al, Opt. Exp. 18, 15484 (2010). [4] M. Foster et al, Nature 441, 960 (2006).

[5] C. Husko et al Opt. Exp. 17, 22442 (2009). [6] Hua Ji et alJ. Lightwave Technol. 29, 426 (2011).

0 0.02 0.04 0.06 0.08 0.1

10

20

30

40

50

P0 [W]

Gro

up Index [n g

]

(TPA+FCA) - FWM (difference), L = 5 mm

(

dB

),

= 3

nm

-8

-6

-4

-2

0

2

4

6

8(a) (b) (c)

PhC

NW

105


106


Spontaneous symmetry breaking in nonlinear gratings with local defects

Irina Kabakova1, Ishraq Uddin1, Jonathan Jeyaratnam1, Martijn de Sterke1 and Boris Malomed2

1Centre for Ultrahigh bandwidth Devices for Optical Systems, School of Physics, University of

Sydney 2Department of Physical Electronics, Faculty of Engineering, Tel Aviv University Tel Aviv 69978,

Israel

Phone: +61 2 93515978


Localized modes in nonlinear gratings with a symmetric pair of defects are studied. These localized modes feature maxima at

positions of the defects and decay exponentially elsewhere. In the low-intensity regime both defects capture equal amount of

energy, whereas the symmetry breaking occurs at higher intensities.

Systems described by symmetric Hamiltonians are expected to have symmetric and antisymmetric eigenstates.

However, the (anti)symmetry can be broken in nonlinear systems when asymmetric states become favorable.

This phenomenon of the spontaneous symmetry breaking (SSB) has been predicted in diverse settings relevant

to optics and matter waves [1-2]. It is also of a particular importance in particle physics and general relativity [3].

For SSB to occur in optics, the system must satisfy three requirements: a) it must consist of, at least, two coupled

parts; b) it must be symmetric; and c) it must be nonlinear. We study the SSB in an optical system based on a

Bragg grating with two mutually symmetric phase-shift defects in a χ(3)-nonlinear medium. In the linear regime,

the system can be solved analytically, giving rise to two localized states. They feature symmetric intensity

distributions with equal maxima at both defects. In Fig. 1 eigenfrequencies of the modes are mapped versus the

energy trapped by the grating. With increasing energy, both resonances shift towards lower frequencies due to

the Kerr nonlinearity. This happens symmetrically, so that the modes shift in parallel to each other, and their

symmetry is preserved (top-right inset to Fig. 1). However, when a critical energy is reached, new asymmetric

states emerge. These have most of the energy trapped by one of the defects (bottom-right inset to Fig. 1). Fig. 2

shows how the asymmetry of the system, Ω , evolves with increasing energy. It is defined as )/()( RLRL IIII ,

with LRI , being intensities at the right and left defects, respectively. We find that the SSB bifurcation in nonlinear

gratings takes the traditional form of a supercritical pitchfork.

0.000 0.001 0.002 0.003

-30

-20

-10

0

10

L=4

L=3

L=2

detu

nin

g

(m

-1)

Energy (a.u)

0.000 0.001 0.002 0.003

-1.0

-0.5

0.0

0.5

1.0 L=4

L=3

L=2

Energy (a.u)

Fig. 1: Resonant frequency versus energy for a grating with strength κ and

two defects separated by distance L. The coupling strength takes values

κL=2, 3 and 4. The frequency detunings cn B /)( are given in relation

to the Bragg condition, BB c / . The field profiles corresponding to the

symmetric and asymmetric modes are shown on the right-hand side.

Fig. 2: SSB bifurcation diagram for different

coupling strengths κL=2, 3 and 4 between

the defects. The asymmetry of the system is

defined as )/()( RLRL IIII .

References [1] K. Hayata and M. Koshiba, J. Opt. Soc. Am. B 9, 1362 (1992).

[2] T. Mayteevarunyoo, B. A. Malomed, and G. Dong, Phys. Rev. A 78, 053601 (2008).

[3] K. Brading and E. Castellani, “Symmetry and Symmetry Breaking,” The Stanford Encyclopedia of Philosophy (Fall 2008 Edition).

107


Complex fiber Bragg gratings for pulse stretching and gain equalization in sub-cycle

waveform synthesizer

Irina V. Kabakova1, Enbang Li1, Eric C. Mägi1, Benjamin J. Eggleton1,

Shu-Wei Huang2, Kyung-Han Hong2 and Franz X. Kärtner2,3

1Centre for Ultrahigh bandwidth Devices for Optical Systems, School of Physics, University of

Sydney, Sydney 2006, Australia 2Department of Electrical Engineering and Computer Science and Research Laboratory of

Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA

3DESY-Center for Free-Electron Laser Science and Hamburg University, Notkestraße 85, D-22607

Hamburg, Germany


We demonstrate complex strongly-chirped fiber Bragg gratings for use in an optical parametric chirped pulse amplifier

(OPCPA), which pumps a sub-cycle waveform synthesizer. These gratings exhibit a superior performance, i.e. they enable

optical delays on the order of 1 ns /1 nm and have a low group delay ripple of 40 ps peak/peak. In addition, the grating

apodization profile can be designed to produce double-hump waveforms in reflection, allowing for compensation of the gain-

narrowing in a regenerative amplifier.

OPCPA is a key technology for producing wavelength-tunable, high peak- and high average-power, few-cycle

optical pulses, essential for time-resolved spectroscopy and strong-field physics experiments. Recently, using

OPCPA-based optical waveform synthesizer, pulses with sub-mJ energies and a spectral width close to two

octaves have been achieved by our collaborators [1]. To avoid damage of optical components during the

amplification, pulses must be stretched in time prior they are launched in the amplifier. Chirped fiber Bragg

gratings (CFBG), fabricated in our laboratory, were used for this purpose as the most flexible approach to pulse

stretching [2]. Thanks to developed theory and mature fabrication technique, CFBGs can be made to have almost

arbitrary amplitude and phase profiles.

In this work we design and inscribe CFBGs to act as an efficient pulse-stretcher in OPCPA laser system. The

grating is typically 10 cm long, with a 1 ns/1 nm chirp rate and only 40 ps peak/peak group delay ripple (see a

Gaussian apodized CFBG in Fig. 1 (a)). Using CFBGs and the concept of “frequency-to-time mapping” we can

achieve instantaneous stretching and shaping of optical pulses in the time domain [3]. The amplitude

apodization and the group delay ripple play a crucial role in the output pulse shape [2]. By applying an

amplitude modulation to the grating strength, we can achieve pulses with “double-hump” shapes. These can be

further exploited in OPCPA laser system, in which pulse shape is expected to compensate for a non-uniform

gain profile in the regenerative amplifier (see schematic in Fig. 1(b)).

Fig. 1: (a) Measurement of the power spectrum and the group delay ripple of a CFBG. (b) Input pulse is reflected by a CFBG,

which stretches and shapes it. Then it is amplified by a regenerative amplifier (RGA) and recompressed by a grating pair.

References 1. S.-W. Huang et al. “High-energy pulse synthesis with sub-cycle waveform control for strong-field physics,” Nat. Photon. 5 475 (2011).

2. I. C. M. Littler, L. Fu, and B. J. Eggleton, “Effect of group delay ripple on picosecond pulse compression schemes,” Appl. Opt. 44 4702 (2005).

3. Q. Liu et al. “Synthesis of fiber Bragg grating for gain-narrowing compensation in high-power Nd: Glass chirped pulse amplification system,” Opt.

Fiber. Tech. 17 185 (2011).

108


Characterization of Mid-infrared Photonic Crystal Cavities

K. J. Lee,1 C. Reimer,2,3 L. O'Faolain,3 C. Grillet,1 E. Magi,1 D. Hudson,1 C. Husko,1

S. Jackson,1 D. Moss,1 T. F. Krauss,3 and B. J. Eggleton1 1Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS), School of Physics,

University of Sydney, NSW 2006, Australia 2Department of Physics, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany

3School of Physics and Astronomy, SUPA, University of St Andrews, St Andrews, Fife KY16 9SS,

UK

Phone: 0439 402 451


We built the free-space optical setup to characterize mid-infrared photonic crystal (PhC) cavities. The technique relies on the

resonant scattering method exhibiting Fano-type spectral response.

Integrated photonic devices operating in mid-infrared (MIR) spectral region attract increasing interests due to

their various potential applications including spectroscopy, environmental gas detection, and bio-sensing. One

of such device types of interest is the high quality (Q) factor resonant cavities capable to confine light tightly,

which allows realizing either nano-cavity lasers or nonlinear optical devices due to their enhanced

nonlinearities. Recently, first MIR PhC cavities have been realized in silicon on insulator (SOI) platform [1]. In

this work, we built a free-space optical setup to characterize MIR PhC cavities, and the technique relies on the

resonant scattering method exhibiting Fano-type spectral response [2]. Figure 1 illustrates the schematic of the

experimental setup with a vertical coupling configuration, where the fundamental resonance of the cavities is

probed from vertical incidence using cross-polarized reflectivity [2]. Inset of Fig. 1 shows the SEM image of MIR

L3 cavity formed by removing three adjacent holes in a triangular PhC lattice, where two inner holes (marked in

yellow) at the end of the cavities were shifted outwards and their radius was decreased for higher Q-factor [1].

The cavities are designed and fabricated in Univ. of St. Andrews, and some of cavity structures are optimized for

the higher vertical out-coupling efficiency in the far-field radiation pattern by modifying the sizes of holes

marked in magenta as shown in the inset of Fig. 1 [3].

Fig. 1: Schematic of experimental setup used to characterize the mid-IR photonic crystal cavities. Inset shows the SEM image

of a L3 PhC cavity with lattice period of a = 1160 nm and radius of r/a = 0.28. Two inner holes are shifted outwards with s/a =

0.20 and they have a smaller radius with r/a = 0.23. Holes marked in magenta are enlarged to increase the vertical out

coupling [3]. NIR: near infrared; MIR: mid-infrared.

References 1. R. Shankar, R. Leijssen, I. Bulu, and M. Lončar, “Mid-infrared photonic crystal cavities in silicon,” Opt. Express 19, 5579-5586 (2011).

2. M. Galli, S. L. Portalupi, M. Belotti, L. C. Andreani, L. O’Faolain, and T. F. Krauss, “Light scattering and Fano resonances in high-Q

photonic crystal nanocavities,” Appl. Phys. Lett. 94, 071101 (2009).

3. M. Galli, D. Gerace, K. Welna, T. F. Krauss, L. O'Faolain, G. Guizzetti, and L. C. Andreani, “Low power continuous-wave generation of

visible harmonics in silicon photonic crystal nanocavities,” Opt. Express 18, 26613-26624 (2010).

ZnSe lens

ZnSe lens

Polariser (0)

Polariser (90)

QCL

Visible/NIR camera

Mid-IR detector (TE cooled MCT detector)

Sample (45)

Rotation stage

xyz stage

Ge filter

Visible source/OSA

MIR BS

NIR BS

QCL: Quantum cascaded laser (Daylight solutions)

= 3.8 ~ 4.1 m

NIR

MIR

109


Low Refractive Index Biosensor Based on Composite Polymer Fiber Directional Coupler

Kwang Jo Lee,1 Nelly Vuillemin,2 Alexander Argyros,1 Sergio G. Leon-Saval,1 Richard Lwin,1

and Boris T. Kuhlmey1 1Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS), Institute of Photonics and

Optical Science (IPOS), School of Physics, NSW 2006, Australia 2Ecole Centrale Marseille, Pôle de l'Etoile, Technopôle de Château-Gombert, 38, rue Frédéric Joliot-

Curie, 13451

Phone: 0439 402 451


We propose and fabricate a novel refractive index sensor designed for low index bio-medical sensing. The device is based on

a directional coupler implemented in a single micro-structured polymer fiber including two waveguides within it: a

composite core and a hollow satellite channel running parallel with the core.

Fiber-optic refractive index (RI) sensors have been widely studied in recent years for diverse applications in environmental

monitoring, metrology, chemical and bio-medical sensing [1]. In bio-sensing, analytes with bio-molecules are mostly given as

water-based solutions whose indices are around 1.33, so that the RI sensors operating in the low-index region is highly

desirable for bio-medical applications. In this work, we propose a novel RI sensor satisfying all of the desirable properties for

practical bio-sensors: not requiring any complicated post-processing, suitable for low-index sensing, and having the

simplicity that lengthy optical alignment is unnecessary during the basic sensor operation [2]. The sensor fiber incorporates

two waveguides within it: a composite core designed to be single moded with large mode area, and a hollow satellite

channel running parallel to the core [Fig. 1]. For the low-index sensing, the channel is coated with a high-index material

along its length, acting as an optofluidic waveguide when filled with low-index analyte [3]. The various index contrasts are

achieved using polymer drawing techniques, which compared to glass drawing techniques provide higher index contrasts

and fibers that are easier to handle in biomedical environments. The cross-section of our fabricated sensor fiber is shown in

Fig. 1 (d). Simulations predict that the fabricated fiber should have a detection limit for low-index sensing of ~ 3 10-6 RIU,

which can be improved to ~ 2 10-6 RIU by further optimization. Our sensor is readily applicable to bio-sensing through

antibody functionalization, and the detection limit for measuring the streptavidin molecules is predicted to be of order 2.5

g/mL.

Fig. 1: (a) Schematic diagram of the directional coupler geometry within a polymer fiber. (b) Example of effective index

curves of core and satellite modes showing the resonance feature when the material dispersion is ignored. (c) Proposed

optical setup operating as reflection type for low-index sensing OSA: optical spectrum analyzer, SMF: single mode fiber,

MMF: multi-mode fiber. (d) Microscopic images of the sensor fiber cross-section.

References 1. D. K. C. Wu, B. T. Kuhlmey, and B. J. Eggleton, “Ultrasensitive photonic crystal fiber refractive index sensor,” Opt. Lett. 34, 322-324 (2009).

2. K. J. Lee, N. Vuillemin, A. Argyros, S. G. Leon-Saval, R. Lwin, and B. T. Kuhlmey, “Low refractive index sensor for bio-medical sensing

based on composite polymer fiber directional coupler,” Opt. Express to be submitted.

3. B. T. Kuhlmey, S. Coen, and S. Mahmoodian, “Coated photonic bandgap fibers for low-index sensing applications: cutoff analysis,” Opt.

Express 17, 16306-16321 (2009).

High reflection coatingFibre core

Coupled lightDirectional coupling

Low-index liquid analyte

Reflected light

Analyte hole

High-index polymer ring

Input light

Circulator

Broad spectrum

source

Analyte

OSA

SMF

T

(b)

Polymer fibre

Reflected light

Sensor fibre

Dipping

MMF

Core mode

Satellite modeneff

r

(d)

r

Lc

r

r

SNRTmin

(c)

(a)

Composite core

Satellite channel

110


111


112


Slow-light Enhanced Correlated Photon-pair Generation

C. Xiong1, C. Monat1, 2, M. Collins1, A. Clark1, C. Grillet1, G. Marshall3,

M. J. Steel3, J. Li4, L. O'Faolain4, T. F. Krauss4 and B. J. Eggleton1 1Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS), School of Physics,

University of Sydney, NSW 2006 2Institut des Nanotechnologies de Lyon, Ecole Centrale de Lyon,

36 Avenue Guy de Collongue, 69134 Ecully, France 3CUDOS, Department of Physics & Astronomy, Macquarie University, NSW 2109, Australia

4School of Physics and Astronomy, University of St Andrews, Fife, KY16 9SS, UK

Phone: +61 2 90369430 Email: [email protected]

We generate correlated photon pairs in the telecom band from a 96 µm long dispersion-engineered silicon photonic crystal

waveguide. The spontaneous four-wave mixing process producing the photon pairs is enhanced by slow-light propagation.

The integration of optical components for use in emerging quantum technologies such as quantum-secured

communication is under intense investigation. A bright, efficient and triggerable single-photon source in the

low-loss telecom bands is a key requirement for many applications. A common strategy is to generate correlated

photon pairs using a spontaneous nonlinear process, with the detection of one photon “heralding” the arrival of

the other. As nonlinear pair generation is stochastic, achieving scalability in such devices will require the on-chip

integration of many identical pair sources, allowing the parallel generation of many photons. Architectures

investigated for such sources include periodically poled lithium niobate (PPLN) waveguides and chalcogenide

glass waveguides, using three-wave and four-wave mixing respectively. The drawbacks of such sources include

active temperature control and mode matching (PPLN), and significant Raman noise (chalcogenides). In this

light, silicon is an attractive platform for creating parallel on-chip quantum sources, due to its high χ(3)

nonlinearity, its potential for on-chip switching, an extremely narrow Raman gain spectrum and natural CMOS

compatibility. Indeed correlated photon pairs have been generated from silicon nanowires with path lengths of

as long as 1 cm.

As quantum information is increasingly demanding many-photon input states, a mature silicon source

might eventually contain hundreds of individual pair generation units combined with intelligent routing as the

photons appear. To make this a reality, a more compact and efficient individual generation unit is a critical

development. Here we report the generation of correlated photon pairs in the telecom band using spontaneous

four-wave mixing (SFWM) from a 96 µm silicon photonic crystal (PhC) waveguide operating in a dispersion-

engineered slow light regime (Fig. 1a). The slow-light enhancement of SFWM critically decreases the path length

of the device, making it the most compact emitter of quantum correlated photon pairs yet reported. As shown in

Fig. 1(b), the coincidence to accidental ratio (CAR), a key measurement of the quality of a photon-pair source,

was maximum 26, making this source immediately applicable to many photonic quantum technologies.

Fig. 1: (a) Schematic of SFWM in a silicon slow-light PhC waveguide. (b) The CAR as a function of coupled peak power.

References C. Xiong, C. Monat, A. S. Clark, C. Grillet, G. D. Marshall, M. J. Steel, J. Li, L. O’Faolain, T. F. Krauss, J. G. Rarity, and B. J. Eggleton, “Slow-

light enhanced correlated photon pair generation in a silicon photonic crystal waveguide,” Opt. Lett. 36, 3413–3415 (2011).

0 0.2 0.4 0.6 0.80

10

20

30

5

15

25

35

(a) (b)

CA

R

Coupled peak power (W)


113


Nanofabrication of Photonic Metamaterials

Manuel Decker(1), Isabelle Staude(1), Dragomir Neshev(1), Hoe Tan(2), Michael Ventura(3), Min Gu(3),

Chennupati Jagadish(2), and Yuri Kivshar(1) (1)CUDOS @ Nonlinear Physics Centre, Research School of Physics & Engineering,

Australian National University (2Department of Electronics Materials Engineering, Research School of Physics & Engineering,

Australian National University (3) CUDOS @ Centre for Micro-Photonics, Swinburne University

Phone: (02) 61251006


Artificially engineered metamaterials open up the route for creating materials with electromagnetic properties that cannot

be obtained with natural materials. In particular, so-called negative refractive index metamaterials offer exciting new

prospects for manipulating light. Here we report on the fabrication techniques we employ in order to push the operation

frequency of metamaterials to near-infrared or even visible frequencies.

Since the proposal of the so-called split-ring resonator [1] as fundamental building block of metamaterials

in 1999 and the first realization of a negative refractive index at microwave frequencies [2], much effort has been

spent on downscaling the feature sizes of the fundamental building blocks in order to obtain metamaterials

operational at NIR or even visible frequencies [3-4]. However, only in the past years metamaterials with

operation wavelength in the NIR/visible have been achieved using electron-beam lithography (EBL) as

workhorse for fabrication of those structures with nanometer-scale feature sizes.

(a) (b) (c) (d)

Fig. 1: (a) Fabrication Scheme for EBL. (b) Magnetic metamaterial of split-ring resonators with operation wavelength at about

1.2m wavelength. (c) One-layer fishnet structure. (d) Sample of thin metallic EBL-lines processed on top of a dielectric line

(thick line) using the Hybrid EBL/DLW approach.

We present our recent results on the fabrication of nanoscale magnetic metamaterials using electron-beam

lithography (Fig. 1(a)). We achieve feature sizes below 50nm which is a fundamental step towards metamaterials

operating in the NIR/visible (Fig. 1(b,c)). Furthermore we present first proof-of-principle structures for EBL on

curved surfaces. Using a combination of direct-laser writing (DLW) and EBL we process nanoscale (2D) features

on micro-scale (3D) pre-patterned substrates which enables us to produce 3D metallic structures with very small

feature sizes (Fig. 1(d)). Our results open the way for the realization of novel type functional metamaterials,

including tunable, nonlinear, and 3D metal-dielectric metamaterials.

We acknowledge financial support by the Australian Research Council (ARC). Fabrication facilities used in

this work are supported by the Australian National Fabrication Facility (ACT-node).

References [1] Pendry et al., “Magnetism from Conductors and Enhanced Nonlinear Phenomena,” IEEE Trans. Microw. Theory Tech. 47, 2075 (1999).

[2] Shelby et al., “Experimental Verification of a Negative Index of Refraction,” Science 292, 77 (2001).

[3] S. Linden et al., “Magnetic Response of Metamaterials at 100 Terahertz,” Science 306, 1351 (2004).

[4] Xiao et al., “Yellow-light negative-index metamaterials,” Opt. Lett. 34, 3478 (2009).

1m 500nm 400nm

114


Spatial symmetry breaking in optical metamaterials

C. Helgert1,2, M. Falkner2, E. Pshenay-Severin2, C. Menzel3,

C. Rockstuhl3, F. Lederer3, D. Neshev1, Y. Kivshar1, and T. Pertsch2

1 Nonlinear Physics Centre, Australian National University, ACT 0200, Australia

2 Institute of Applied Physics, Friedrich-Schiller-Universität Jena, Germany 3 Institute of Condensed Matter Theory and Solid State Optics, Friedrich-Schiller-Universität Jena,

Germany


Nanostructured optical metamaterials constituted of artificial metaatoms represent a material class that permits the control

of light propagation beyond that in natural media. In this contribution we present some selected examples of experimentally

investigated metamaterials operating at optical frequencies. It is pointed out how the reduction of spatial symmetries (i.e.

symmetry breaking) of metaatoms enables to study unprecedented regimes of light-matter interaction.

Symmetry is of general and fundamental relevance in physics, since almost every microscopic or macroscopic

system exhibits symmetric relations between its constituents. In this contribution, we wish to show how the

spatial symmetries of nanoscaled, three-dimensional metaatoms, the building-blocks of optical metamaterials,

can be utilized to design their optical response. In particular, the reduction of the degree of spatial symmetry of

a metaatom, commonly referred to as symmetry breaking, is shown to be a decisive means to foster extended or

even completely novel optical material properties that may be unavailable in nature. The optical metamaterials

considered were fabricated by a stand-alone electron-beam lithography technology and comprehensively

characterized for visible and near-infrared wavelengths. In detail, a Swiss cross metamaterial associated with a

negative index of refraction [1, 2], a chiral metamaterial composed of three-dimensional loop-wire nanostruc-

tures exhibiting a record-breaking optical activity [3], and a metamaterial with the lowest possible symmetry

showing the novel effect of asymmetric transmission for linearly polarized light [4] are presented. Moreover, we

consider the case when the symmetry of metaatoms supporting higher order multipoles is sustained, while the

periodic lattice in which they are usually assembled is destroyed in a controlled way. Such positional disorder of

metaatoms will lead us to the transition from perfectly periodic to amorphous metamaterials [5, 6, 7].

Fig.: Scanning electron micrographs of selected optical metamaterials with a decreasing degrees of spatial symmetry. The

insets show schematics of the respective metaatoms. (a) Swiss cross metamaterial with fourfold rotational symmetry from [1].

(b) 3D chiral loop-wire metamaterial from [3]. (c) Metamaterial made of metaatoms with lowest spatial symmetry from [4].

(d) Double cut-wire pair metamaterial from [5], where symmetry breaking occurs with respect to the lattice constant.

References [1] C. Helgert et al., “Polarization-independent negative-index metamaterial in the near infrared,” Opt. Lett. 34, 704 (2009).

[2] C. Menzel et al., “Angular resolved effective optical properties of a Swiss cross metamaterial,” Appl. Phys. Lett. 95, 131104 (2009).

[3] C. Helgert et al., “Chiral metamaterial composed of three-dimensional plasmonic nanostructures,” Nano Lett. 11, 4400 (2011).

[4] C. Menzel et al., “Asymmetric transmission of linearly polarized light at optical metamaterials,” Phys. Rev. Lett. 104, 253902 (2010).

[5] C. Helgert et al., “Effective properties of amorphous metamaterials,” Phys. Rev. B 79, 233107 (2009).

[6] C. Helgert et al., “Effects of anisotropic disorder in an optical metamaterial,” Appl. Phys. A 103, 591 (2011).

[7] C. Rockstuhl et al., “Scattering properties of meta-atoms,” Phys. Rev. B 83, 245119 (2011).

(a)(a) (b)(b) (c)(c) (d)(d)

5 µm5 µm2 µm2 µm2 µm2 µm 1 µm1 µm

115


Broadband and Actively Tuneable Arrayed Plasmonic Nanoantennas for Optical

Communications and Sensing

Ivan S. Maksymov, Andrey E. Miroshnichenko, and Yuri S. Kivshar



Phone: +61-2-6125-9074


We suggest a simple and efficient way to enhance the bandwidth and tune dynamically the operating frequency of arrayed

plasmonic nanoantennas. We demonstrate the capability of arrayed nanoantennas to perform as a bistable optical device,

which opens up novel opportunities for optical communication and other kinds of all-optical light control at the nanoscale.

We also explore the use of arrayed nanoantennas for nanoscale optical sensing.

Plasmonic nanoantennas have become a subject of considerable theoretical and experimental interest. Several

potential applications of nanoantennas have been considered including optical communication and sensing.

Arrayed nanoantennas brightly represented by Yagi-Uda and log-periodic architectures, downscaled to

nanometric dimensions, are particularly suited for these applications owing to high directivity and emission

enhancement. However, they are intrinsically narrowband due to the wavelength selectivity of their arrays.

Making them wavelength tuneable over a wide spectral range would allow a smaller nanoantenna to behave as

a larger nanoantenna or as an array of

nanoantennas, both saving space and

improving performance.

We suggest a novel type of broadband

unidirectional arrayed nanoantennas [1, 2]

consisting of plasmonic nanorods of

gradually varying length [Fig. 1(a)]. The

nanorods can be driven by quantum

emitters placed in the near-field zone. As the

optical response of the nanoantenna

depends on the resonance frequency of the

excited element given by its dimensions, the

excitation of shorter nanorods shifts the nanoantenna operation towards shorter wavelengths [Fig. 1(b)].

The tapered nanoantenna design can be used for the new generation of optical nanosensors. We suggest placing

active nanoparticles, sensitive to chemical substances and biological agents, in the close vicinity of individual

nanoantenna elements at the points of subwavelength light confinement and enhancement (excitation sites

n=1...20 in Fig. 1(a)). The change in the optical properties of the nanoparticles on exposure to e.g. inflammable

gases influences the response of the nanoantenna at characteristic operating wavelengths given by the

nanoantenna architecture [Fig. 1(b)]. It makes the nanoantenna attractive for nanoscale sensing applications,

including real-time monitoring low concentrations of gases and observation of chemical or biological events at

the nanoscale.

We also suggest to exploit the free carrier nonlinearity of semiconductors for a dynamical tuning of the

operating wavelength of a plasmonic Yagi-Uda nanoantenna. We modify the feeding element as compared with

previous designs and consider a semiconductor nano-disk squeezed by two identical nanorods. The illumination

of the feeding element with a laser beam alters the conductivity of the nano-disk and enables a monotonic

tuning of the operating wavelength of the nanoantenna in a very wide spectral range as compared with that of

conventionally designed Yagi-Uda nanoantennas.

References [1] I. S. Maksymov, A. R. Davoyan, Yu. S. Kivshar, “Enhanced emission and light control with tapered plasmonic nanoantennas,” Appl. Phys. Lett.

99, 083304, (2011).

[2] A. E. Miroshnichenko, I. S. Maksymov, A. R. Davoyan, C. Simovski, P. Belov, Yu. S. Kivshar, “An arrayed nanoantenna for broadband light

emission and detection," Physica Status Solidi RRL 5, 347, (2011).

Fig. 1 (a) Tapered nanoantenna excited by an emitter (red arrow)

placed at the excitation site n=4. (b) Operating wavelength of the

nanoantenna excited alternately with emitters at n=1...20 [2].

116


Hot Spot in the Interference Pattern of Airy Surface Plasmons

A. Minovich1, A. E. Klein2, N. Janunts2, T. Pertsch2, D. N. Neshev1,, and Y. S. Kivshar1

1Centre for Ultrahigh bandwidth Devices for Optical Systems

Nonlinear Physics Centre, RSPE, Australian National University 2Institute of Applied Physics, Friedrich-Schiller-Universität Jena,

Phone: +61-4-61259076


We analyse the interference pattern of two Airy surface plasmons and study the dependence of the characteristics of a hot

spot in the field distribution on separation distance and angle of incidence of the excitation beam.

Airy surface plasmons tightly confine radiation energy near metal-air interface and possess a number of

remarkable properties. They do not diffract inside their diffraction free zone, they propagate along a parabolic

trajectory, and they recover their shape after passing obstacles. These properties make Airy plasmons attractive

for surface manipulation of nano-objects. However, such an operation requires a narrow high contrast field

region. For 3D radial Airy beams in free space it was shown that a high intensity hot spot can be created in their

focus for a range of beam parameters [1]. Our study show that in the case of 2D Airy plasmons propagating

alone a metal surface such a hot spot can be also obtained in the interference pattern of two beams {Fig. 1(a)].

Fig. 1: (a) Interference pattern of two Airy plasmons (separation distance 2.5 μm). (b) The dependence of the maximum of

intensity on the separation distance. (c) FWHM (along x) versus separation distance. Beam parameters are x0=0.7 μm,

λ0=0.784 μm, a=0.04.

The characteristics of the focal region depend on the separation distance between the wave packets as well as on

the beam parameters. Thus, for paraxial beams (main lobe width 2x0 ≫ λ0) the hot spot intensity declines

monotonely with separation distance due to the attenuation of surface plasmons. Focal region size, which we

characterise by the Full Width of Half Maximum (FWHM), also decreases tending to a certain limit. However,

different picture is observed for non-paraxial beams. The intensity of the hot spot grows at the beginning and

reaches maximum at some separation distance [Fig. 1(b)]. After that point it declines monotonely. The behavior

of the FWHM is similar to that in the paraxial case [Fig. 1(c)]. However, the existence of the intensity peak and

the fact that the non-paraxial Airy surface plasmons intersect closer to the beam origin due to the higher

curvature of their trajectories, makes the second case more attractive for obtaining of a narrow high contrast hot

spot. In addition, our study shows that a slight tilt of the excitation beam in xy-plane causes the shift of the focal

maximum in x-direction. That provides a tool to control the position of the hot spot which is crucial for a surface

tweezers application. Currently we are working to support our theoretical studies with experimental data.

References [1] N. K. Efremidis, and D. N. Christodoulides, “Abruptly autofocusing waves,” Opt. Lett. 35, 4045, (2010).

117


Optically induced antiferromagnetism in hybrid metamaterials

Andrey E. Miroshnichenko1, Boris L k’yanch k2, Stefan Maier3, and Yuri S. Kivshar1


Nonlinear Physics Centre, Australian National University 2Data Storage Institute, Singapore

3Department of Physics, Imperial College London, UK

Phone: +61-2-61253964


We analyze optically-induced antiferromagnetic response of a novel hybrid metal/dielectric structure consisting of a silicon

nanoparticle coupled to multilayer stacks of split-ring resonators, and observe a strong antiferromagnetic resonance with a

staggered pattern of the induced magnetization field. A periodic array of such elements will support a novel type of spin

waves.

We study the magnetic response of hybrid metal/dielectric structures

consisting of dielectric nanoparticles and metallic SRRs. By coupling these

two different elements together, we have been able to achieve the magnetic

interaction between the nanoparticles and split-ring resonators. We have

found that the strongest induced magnetic coupling can be of two types –

ferromagnetic, with the same direction of magnetization of both elements,

and antiferromagnetic, with a staggered magnetization pattern [1,2]. The

induced magnetic response of dielectric spheres is connected to the

excitation of the localized modes of a dielectric particle for which the radial

component of the magnetic field does not vanish [3,4]. This resonance

increases the magnetic field in near-field region around the particle.

We consider a small Si nanoparticle of the radius R = 150 nm placed

between two multilayer stacks of copper split-ring resonators of the radii

R2 = 75nm, thickness and gap width g = 10nm [see Fig.1(a)]. By placing

them in a close proximity, we may expect an effective magnetic coupling

between the elements of different origin. Our numerical simulations made

by means of CST Microwave Studio confirm the existence of the induced

strong magnetic coupling in such a hybrid structure. We find that, in addition to the standard ferromagnetic

response where both magnetizations of the nanoparticle and split-ring resonators are parallel, there exist an

antiferromagnetic response with anti-parallel magnetization of both the elements [see Fig.1(b)].

As the next step, we consider a one-dimensional array of the hybrid elements. In such a structure we observe the

formation of antiferromagnetic coupling between silicon nanoparticles. Coupled SRRs play an essential role in

the control of the induced coupling, which can be changed from the ferromagnetic type to the antiferromagnetic

type by changing the position of the gap of individual split-ring resonators.

References

[1] N. Liu, L. Fu, S. Kaiser, H. Schweizer, and H. Giessen, Advanced Materials vol. 20, p. 3829, 2008.

[2] S. Ghadarghadr and H. Mosallaei, IEEE Transactions on Nanotechnology, vol. 8, p. 582, 2009.

[3] C.F. Bohren and D.R. Huffman, Absorption and Scattering of Light by Small Particles, Wiley: 1998.

[4] A.B. Evlyukhin, C. Reinhardt, A. Seidel, B. Luk’yanchuk, and B.N. Chichko, Physical Review B vol. 82, p. 045404, 2010.

1

0.8

0.6

0.4

0.2

0

|S11|

320300280260240220200

frequency, w [THz]

Sphere+SRR Sphere SRR

(a)

ωAFM

ωAFM

-3

-2

-1

0

1

2

3M

ag

ne

tic f

ield

, H

y/H

0

21.510.5

distance, R [mm]

Sphere

SRR

(b)

(a)

Fig. 1: (a) Schematic view of the hybrid

structure consisting of dielectric spheres

and SSRs; (b) Dependence of the

magnetic response on the distance

between two elements. There is a critic

distance where the flip of

magnetization takes place.

118


Plasmonic light trapping for III-V quantum dot solar cells

S. Mokkapati, H. Lu, L. Fu, G. Jolley, H. H. Tan and C. Jagadish

Electronic Materials Engineering, RSPE, Australian National University

Phone: 02 6125 50355


Scattering from silver (Ag) nanoparticles is used to enhance the long wavelength light absorption in InGaAs/GaAs

quantum dot solar cell. Plasmonic light trapping increases the short circuit current density and open circuit voltage of the

solar cell by 5.3% and 0.9% respectively, leading to an overall efficiency enhancement of 7.7%.

Along with the ongoing research and industry development to reduce the cost of conventional photovolatic

devices such as Si-based solar cells, significant research efforts are currently focused on exploring new concepts

and approaches for high efficiency solar cells. By incorporating self-assembled QDs into a solar cell, photons in

the solar spectrum with energy lower than the energy gap of the bulk host material can be absorbed by the QD

layers, leading to an extended photoresponse into longer wavelengths and hence larger photocurrent. Even

though quantum dots (QDs) extend the photoresponse of solar cells into the long wavelength region, their

contribution to the short-circuit current density, Jsc is still very small due to a very small QD absorption cross

section. We propose to enhance the long wavelength photon absorption of the QD solar cells by employing light

trapping. Light trapping refers to the phenomenon of increasing the path length of light and hence total

absorption inside a thin absorber layer.

Light trapping can be achieved by depositing metal nanoparticles on the solar cell surface1. The light incident on

the nanoparticles is scattered strongly due to excitation of localized surface plasmons. A fraction of scattered

light is coupled into the solar cell. The nanoparticles scatter light at random angles and the light coupled into the

cell at angles greater than the critical angle for total internal reflection at the cell/air interface is trapped inside

the cell, and results in enhanced absorption in the cell (in the far-field of the nanoparticles). Figure 1(a) shows

the schematic of the plasmonic solar cell studied in this work.

Figure 3: (a) Schematic of the InGaAs/GaAs QD solar cell structure used in this study. (b) Device parameters for the QD solar

cells, before (underlined numbers in italics) and after deposition of the plasmonic nanoparticles.

The performance parameters of the plasmonic solar cell studied are shown in Figure 1(b). Plasmonic solar cell

results in 5.3% enhancement in Jsc and 0.9% enhancement in open-circuit voltage (Voc) with respect to the

reference solar cell, leading to a corresponding efficiency (η) enhancement of 7.7%. Jsc enhancement in the

plasmonic solar cells is due to enhanced absorption in the QD region of the solar cell. In this presentation, we

will discuss the mechanism involved and design optimization of plasmonic quantum dot solar cells.

We would like to acknowledge financial support from ARC and technical support from ANFF.

1. Harry A. Atwater and Albert Polman, Plasmonics for improved photovoltaic devices, Nat. Mater., 9 (3), 205 (2010).

119


Fabrication of Advanced Photonic Nanoantennas

Isabelle Staude[1], Manuel Decker[1], Ivan S. Maksymov[1], Dragomir Neshev[1], Michael Ventura[2],

Hoe Tan[3], Min Gu[2], Chennupati Jagadish[3] and Yuri Kivshar[1]

[1] CUDOS @ Nonlinear Physics Centre, Research School of Physics & Engineering,

Australian National University [2] CUDOS @ Centre for Micro-Photonics, Swinburne University

[3] Department of Electronic Materials Engineering, Research School of Physics & Engineering,

Australian National University

Phone: (02) 6125 1006


Tapered Yagi-Uda nanoantennas offer unique opportunities for enhancing and directing the emission of single quantum

emitters while providing broadband functionality. Here we present the experimental realization of these theoretically

proposed antenna structures using electron-beam lithography. Furthermore, we suggest a novel hybrid fabrication approach

for three-dimensional nanoantenna structures.

Owing to their unique potential regarding applications, e.g., in optical communication, non-classical light

emission, and sensing, plasmonic nanoantennas have recently become a subject of considerable interest [1]. By

placing a nanoscale quantum emitter into the hot spot of a Yagi-Uda nanoantenna its emission can be strongly

enhanced and made highly directional [2,3]. While the Yagi-Uda nanoantennas realized so far are designed to

operate at a single frequency, a recent theoretical study suggests that this limitation can be overcome by a

tapered design of the nanoantenna’s director elements [4]. In addition, using the same design principle, the

antenna gain can be improved and its longitudinal dimensions can be reduced [5]. For our experiment we have

fabricated tapered Yagi-Uda nanoantennas for broadband functionality using electron-beam lithography (EBL)

followed by gold evaporation and a lift-off procedure. Images of the fabricated antennas are presented in Fig. 1

(a)-(c). Different taper angles have been realized in order to study the influence on antenna performance.

Furthermore we propose a novel fabrication approach which is expected to allow for the realization of

three-dimensional nanoantenna structures with 50 nm feature sizes. This approach combines the pre-patterning

of a substrate via direct laser writing (DLW) with a subsequent EBL step. A proof-of-principle demonstration of

this scheme is shown in Fig. 1 (d). The high-quality of fabrication suggests the development of novel

nanoantenna devices for wide range of application ranging from quantum optics to optical communications.

We acknowledge financial support by the Australian Research Council. Fabrication Facilities used in this

work are supported by the Australian National Fabrication Facility.

References [1] L. Novotny and N. van Hulst, “Antennas for light,” Nature Photon. 5, 83-90 (2011).

[2] G. Curto et al., “Unidirectional Emission of a Quantum Dot Coupled to a Nanoantenna,” Science 4, 930–933 (2010).

[3] T. Kosako, Y. Kadoya, and H. F. Hofmann, “Directional control of light by a nano-optical Yagi Uda antenna,” Nature Photon. 4, 312–315 (2010).

[4] I. S. Maksymov et al., “Multifrequency tapered plasmonic nanoantennas,” accepted Opt. Commun (2011).

[5] I. S. Maksymov, A. R. Davoyan, and Yu. S. Kivshar, “Enhanced emission and light control with tapered plasmonic nanoantennas,” Appl. Phys.

Lett. 99, 083304 (2011).

Fig. 1: (a) Scanning electron micrographs of tapered Yagi-Uda nanoantennas with nominal taper angles of 1.2, 3.0, 6.6,

and 9.0 degrees, fabricated by EBL; (b) shows a close-up of the highlighted region, (c) an oblique-incidence view. (d)

Proof-of-principle realization of three-dimensional gold structures obtained by EBL on a DLW pre-patterned

substrate.

http://physics.anu.edu.au/eme

http://physics.anu.edu.au/eme

120


Classical optical simulation of bi-photon generation in quadratic waveguide arrays

M. Gräfe1, A. S. Solntsev2, R. Keil1, A. Tünnermann1, S. Nolte1,

A. Szameit1, A. A. Sukhorukov2, and Yu. S. Kivshar2 1Institute of Applied Physics, Friedrich-Schiller-University Jena, Germany


Nonlinear Physics Centre, RSPE, Australian National University, Australia

Phone: +61 2 6125 8276


We suggest and realize experimentally an optical platform where linear evolution of classical light simulates bi-photon

generation through spontaneous parametric down-conversion and correlated quantum walks in waveguide arrays,

including the regime of violated Bell's inequality.

Entangled photon pairs, so-called biphotons, enable various applications such as quantum cryptography,

teleportation and quantum computation. A particular approach to realize strong quantum correlations of

entangled photons is their propagation in optical waveguide arrays [1]. Recently, it was suggested [2] that bi-

photons can be generated directly in a quadratically nonlinear waveguides array through spontaneous

parametric down conversion (SPDC), enabling flexible control of non-classical correlations at the output.

Fig. 1: (a) Sketch of 1D quadratic nonlinear waveguide array with pump coupled to the edge waveguides and output

detectors of generated bi-photons. (b) Linear optical structure in the form of 2D waveguide array for classical optical

simulation of photon generation; pump beam is coupled to the outer waveguides. (c) Experimental output intensity

distribution for structure in (b). (d,e) Numerical modeling and (f,g) experimental classical measurement results for (d,f) bi-

photon correlations and (g,h) non-classicality, when pump is coupled symmetrically to the edge waveguides.

In this work we reveal that linear propagation of classical light beams can be used to simulate a nonlinear effect of

SPDC leading to photon pair generation and quantum walks of the generated bi-photons. We demonstrate that the

quantum correlations of bi-photons generated in a quadratically nonlinear one-dimensional (1D) waveguide

array [Fig. 1(a)] can be mapped onto a linear beam propagation in specially designed two-dimensional (2D)

array of coupled optical waveguides. Specifically, we propose that when pump is coupled to the first and last

waveguides of the array, this is simulated by introducing additional waveguides at the corners of an equivalent

2D array, as shown in Fig. 1(b). We fabricated 3x3 arrays of 9.9 cm long waveguides via the femtosecond laser

direct writing technique [3] in fused silica. Laser light of 633 nm wavelength was injected to the pump

waveguides, and the output intensity detected with a CCD [Fig. 1(c)] directly determines the bi-photon

probability distribution [Fig. 1(f)] providing 96.86% similarity with the theoretical predictions [Fig. 1(d)]. We

further confirm that our classical optical simulator correctly reproduces a non-clasicality function defined

according to Ref. [1], where positive values reflect violation of Bell’s inequality [Fig. 1(e,g)].

References [1] A. Peruzzo et al., Science 329, 1500 (2010).

[2] A. S. Solntsev, A. A. Sukhorukov, D. N. Neshev, and Yu. S. Kivshar, Phys. Rev. Lett. (2011) in press; arXiv :1108.6116.

[3] A. Szameit et al., Appl. Phys. B 82, 507 (2006).

121


Observation of spontaneous parametric down conversion in LiNbO3 waveguide array

Alexander S. Solntsev1, Frank Setzpfandt2, Allen Wu1, Dragomir N. Neshev1,

Andrey A. Sukhorukov1, Thomas Pertsch2, and Yuri S. Kivshar1 1Centre for Ultrahigh bandwidth Devices for Optical Systems

Nonlinear Physics Centre, RSPE, Australian National University, Australia 2Institute of Applied Physics, Friedrich-Schiller-University Jena, Germany

Phone: +61-2-6125-3792


We characterize experimentally the spectral-spatial distribution of bi-photons generated in the process of spontaneous

parametric down-conversion in LiNbO3 waveguide arrays. We demonstrate the spectral features which are fundamentally

different from bulk media, in agreement with our theoretical analysis.

Spontaneous parametric down-conversion (SPDC) is one of the most commonly used sources of entangled

photon pairs. Traditionally, bulk optical schemes are used both for generating bi-photon and for their

manipulation, such as building logic gates. However with increasing complexity of quantum control schemes,

integrated optical circuits provide important solution to the scalability and stability of the quantum optical

devices. In particular, waveguide arrays are seen as one of most important on-chip quantum optical elements

[1]. It was predicted that a nonlinear waveguide array allows for generation of photon pairs with controllable

spatial quantum correlations [2]. The spectral dynamics of the system however has not been experimentally

studied so far. In this work we report experimental measurements of the spectrally resolved spatial SPDC

output of LiNbO3 array [Fig. 1(a)]. Arrays with and without periodic poling have been tested experimentally.

Fig. 1: (a) A nonlinear waveguide array. (b,d) Experimental and (c,e) theoretical normalized spontaneous parametric down-

conversion spatially-resolved spectra for (b,c) degenerate phase-matching and (d,e) non-degenerate phase-matching.

For periodically poled LiNbO3 array, in the degenerate regime with pump wavelength λp=776.5 nm we observe

one peak of SPDC generation, both in the spectral and spatial domains [Fig. 1(b,c)]. When the pump wavelength

is decreased to 775nm, more than two spectral peaks satisfy the phase-matching conditions [Fig. 1(d,e)]. This

observed dynamics is in excellent agreement with our theoretical modeling [Fig. 1(c,e)]. The results attest to

feasibility of the LiNBO3 waveguide arrays for integrated quantum devices with tunable quantum statistics,

which is qualitatively different from statistics of bi-photons generated in bulk crystals.

References [1] A. Peruzzo, M. Lobino, J. C. F. Matthews et al., Science 329, 1500 (2010).



122


Fig.1: Multiple IFM measurements using wavelength channel labelling

Fig. 2: Remoted Instantaneous Frequency Measurement System

MZM HNLF

AW

G2

PD

Lock in

Amplif ier

CFBG

Ch5

AW

G1

Ch1 Ch3Ch4

Dither (f1=13kHz)

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A

PD

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LD2

(4)

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Filter1 Filter2EDFA2

1

C D E F G HB

All Optical Mixing for Microwave Photonic Instantaneous Frequency Measurement

Lam Anh Bui and Arnan Mitchell



Phone: +61 3 9925 2896


This poster will review the studies of nonlinear optical mixing in highly nonlinear fibre for microwave photonic

instantaneous frequency measurements (IFM). We will discuss the development of a comprehensive suite of tools for

simultaneous frequency measurements in a single HNLF including seamlessly extension to multiple measurements,

remoted frequency measurements and unambiguous measurement of both signal frequency and amplitude.

Within this project, we have explored the nonlinear optical wave mixing in highly nonlinear fibre (HNLF) to

realise novel frequency measurement of analogue RF and microwave signals. In particular, we have focused on

a few important directions: (i) Extension seamlessly to multiple parallel measurements using wavelength

channel labeling (ii) Conceiving and demonstrating the concept of remoted IFM in which frequency

measurement could be performed on a standard RF photonic link and (iii) Conceiving the concept of

unambiguous measurements of instantaneous signal frequency and amplitude.

Seamlessly extension to multiple parallel

measurements in a single HNLF: We

previously demonstrated multiple parallel

IFM measurements in a single highly

nonlinear fibre [1]. This however requires

careful selection of channel wavelengths

to allow separation of mixing idles using

optical filtering. To overcome this

limitation, we conceive and demonstrate a

novel technique in which the wavelength

channels are labeled with distinct low

frequency signals to enable isolation of

mixing products even though they may

overlap spectrally and thus significantly

improves the system practicality.

Remoted IFM measurement: Nonlinear

mixing IFM has the advantage of low

noise and high stability. It however requires modulation of two optical carriers at the transmitter. In practical

applications it may not be possible to modify the transmitter in this way and thus it is desirable to perform

frequency measurement on a signal produced by a simple single wavelength transmitter. In this work, we report

on the novel concept of IFM remoting in which the transmitter is a conventional single modulated wavelength.

Unambiguous measurement of both RF signal amplitude and frequency: To claim that an IFM system has been fully

implemented, it would be necessary to provide orthogonal sine and cosine measurements such that both the

amplitude and frequency of the signal can be identified simultaneously and unambiguously. This requires the

use of a Hilbert transform in one arm of the IFM. We have demonstrated techniques to achieve this photonically

and have applied this technique to an IFM system [2]. We are currently exploring system topologies that can

utilize the current demonstrated simultaneous parallel IFM to achieve amplitude/frequency measurements.

The outcomes of this project give us confidence to apply the demonstrated concepts into the next stage of

CUDOS for the development of all optical mixing instantaneous frequency measurement on a chip.

References [1] L.A. Bui, N. Sarkhosh, A. Mitchell, “Photonic Instantaneous Frequency Measurement: Parallel Simultaneous Implementation in a Single Highly

Nonlinear Fibre” IEEE Photonics Journal, Vol. 3, Page 915-925, (2011)

[2] H. Emami, N. Sarkhosh, L. Bui, and A. Mitchell, “Amplitude independent RF instantaneous frequency measurement system using photonic

Hilbert transform”, Optics Express., Vol. 16, no. 18, pp. 13 707–13 712, (2008)

123


124


Domain engineering in LiNbO3 waveguides by strongly absorbed UV light Hendrik Steigerwald1,2, Tristan Crasto1, Yongjun Ying3, Elisabeth Soergel4,

Vijay Sivan1, and Arnan Mitchell1,2

1School of Electrical and Computer Engineering, RMIT University, GPO Box 2476V, Melbourne,

Victoria 3001, Australia 2Center for Ultrahigh bandwidth Devices for Optical Systems (CUDOS), RMIT University, GPO

Box 2476V, Melbourne, Victoria 3001, Australia 3Optoelectronics Research Centre, University of Southampton, Highfield SO17 1BJ, UK

4Institute of Physics, University of Bonn, Wegelerstr. 8, 53115 Bonn, Germany

Phone: +61399253250


Ferroelectric domain patterning of Ti in-diffused waveguides on the non-polar faces of lithium niobate crystals by strongly

absorbed UV light is demonstrated for the first time. Investigation of the domain patterns by piezoresponse force microscopy

and waveguide characterization are performed to demonstrate the suitability of this platform for fabrication of non-linear

optical device.

Domain engineering in lithium niobate (LiNbO3) has become an active field of research and enables plenty of

advanced applications that can be realized employing tailored domain structures. The most prominent example

is frequency conversion using quasi-phase matching in periodically poled crystals. The strong light confinement

in waveguides, just below the surface, offers the advantage of a good overlap between the few-µm-deep domain

patterns and the light propagating inside the waveguide [1]. Hence, domain patterning methods which do not

generate bulk domains, e.g. poling inhibition [2] or direct writing by UV light [3], can be utilized to generate

periodically poled waveguides in LiNbO3.

Single mode waveguides for light of a wavelength of 1.55 µm on the x-face of LiNbO3 crystals are generated by

in-diffusion of photolithographically patterned, 85-nm-thick Ti layer at 1380 K for 15 hours. Then the x-face is

irradiated by strongly absorbed UV light with a wavelength of 275 nm. As shown in figure 1(a), the light is

focussed to a spot with a diameter of 6 µm, locally heating the crystal surface close to the Curie temperature. The

laser focus is scanned perpendicular to the waveguide into the crystallographic –z direction, subsequently

irradiating stripes with a width of 9.3 µm and a spacing of 9.3 µm. The UV-irradiated tracks are then

investigated by piezoresponse force microscopy (PFM).

The PFM images in figure 1(b) and 1(c) show that a domain pattern with a period length of 18.6 µm is generated

inside the waveguides also inducing some surface roughness through thermal damage of around 10 nm, which

is below the height of the ridge of 150 nm that is generated by Ti in-diffusion.

Fig. 1: (a) Experimental setup for direct writing of domains by UV light, (b) Piezoresponse image of a UV-irradiated

waveguide (c) Topography image of the same area showing the actual waveguide as a bright line.

References [1] C. L. Sones, P. Ganguly, Y. J. Ying, E. Soergel, R. W. Eason, S. Mailis, “Poling-inhibited ridge waveguides in lithium niobate crystals,” Appl.

Phys. Lett. 97, 151112, (2010).

2] C. L. Sones, A. C. Muir, Y. J. Ying, S. Mailis, R. W. Eason, T. Jungk, Á. Hoffmann, E. Soergel, “Precision nanoscale domain engineering of

lithium niobate via UV laser induced inhibition of poling,” Appl. Phys. Lett. 92, 072905, (2008).

[3] H. Steigerwald, Y. J. Ying, R. W. Eason, K. Buse, S. Mailis, and E. Soergel, “Direct writing of ferroelectric domains on the x- and y-faces of

lithium niobate using a continuous wave ultraviolet laser,” Appl. Phys. Lett. 98, 062902, (2011).

10 µm

(a) (b) (c)

125


Waveguide approaches to engineered coupled quantum systems

Andrew D. Greentree¹, Kelvin Chung, Timothy Karle, Snjezana Tomljenovic-Hanic

¹School of Physics, The University of Melbourne

Phone: +61 3 8344 5082


As the understanding of fundamental quantum systems improves, the state of the art has shifted from the

observation of quantum effects to the engineering of quantum systems fit for specific tasks. Obvious

applications are in the field of quantum sensing and quantum information processing, but more generally the

engineering of quantum states represents the ultimate limit of control of any system. Here we explore analogies

between coupled waveguide systems and solid-state quantum devices. In particular we will show designs for

devices based around spatial adiabatic passage protocols as toy systems that illustrate this concept.

126


Ultraviolet in the Ultrafast Lane

Coutts D W, Granados E, Stark SP, Wentsch K, Palmer G, Fuerbach A, and Spence D J

MQ Photonics Research Centre, and


Physics and Astronomy, Macquarie University

Phone: 02 98508970


Cerium doped fluoride lasers, with their high efficiency and ultrahigh gain bandwidth (the same in THz as Ti:sapphire) and

all-solid-state robustness are arguably the Ti:sapphire of the ultraviolet. We show that cerium lasers have the potential to

provide attosecond pulses at MHz pulse rates in the ultraviolet and report our first major steps towards achieving that goal:

generation of ultrafast pulses from a mode-locked cerium laser.

The introduction of Ti:sapphire in the late 1980’s revolutionized several fields of laser technology, particularly

the ultrafast domain where they are the source of few and single cycle optical pulses in the infrared. Indeed, the

Ti:sapphire laser is now the ubiquitous platform for broadly tunable and ultrafast lasers.

Many applications require ultraviolet rather than infrared sources; for example the ultimate short pulse limit is

determined by the optical carrier frequency, so to achieve the shortest possible pulses it is necessary to move

from the infrared Ti:sapphire laser to the ultraviolet and beyond. One common approach to access the ultraviolet

spectral domain is to frequency convert (eg frequency triple) a Ti:sapphire laser. We argue that a better approach

is to generate the desired output directly in the UV using a UV laser.

Cerium doped fluorides have gain bandwidths of order 100 THz which is the same as Ti:sapphire, but in the

ultraviolet. One particularly important cerium laser is the Ce3+:LiCaAlF6 laser which can be conveniently

pumped by the fourth harmonic of Nd:YAG lasers at 266 nm and produces tunable output from 282 nm –

315 nm.

We have recently shown for the first time that this material not only operates very well in the standard

nanosecond pulsed regime (where broad tunability and efficiencies of order 50% are readily obtained), but can

also be operated as a mode-locked laser and as a tunable continuous wave laser [1]. These are the first critical

steps to establishing cerium as a powerful new ultrafast laser platform capable of producing single cycle pulses

down in the attosecond domain.

So far we have only measured picosecond pulses at 289-292 nm, a spectral width that indicates these pulses are

not bandwidth limited. It may be the case that the laser is in fact generating chirped femtosecond pulses as

would be expected for a mode-locked laser without any dispersion control. The next major steps are to introduce

intracavity dispersion compensation (chirped ultraviolet mirrors have been designed), use better 266 nm pump

sources that we have developed and to use better quality laser crystals we now have available.

References

1 E. Granados, D. W. Coutts, D. J. Spence, “Mode-locked deep ultraviolet Ce:LiCAF laser,” Optics Letters 34, pp 1660 2009.

127


Harmonic Oscillator Superradiance in Integrated Photonics

M. Delanty1,2, S. Rebic2, and J. Twamley2

1Centre for Ultrahigh bandwidth Devices for Optical Systems 2Centre for Engineered Quantum Systems


Phone: (02) 9850 4886


Superradiance, the enhanced collective emission of light from a coherent ensemble of quantum systems, has been typically

studied in atomic ensembles. In this work we study the enhanced emission of energy from coherent ensembles of harmonic

oscillators. We show that it should be possible to observe harmonic oscillator superradiance for the first time in waveguide

arrays in integrated photonics.

In 1954 Dicke [1] showed that by confining an ensemble of two level atoms to a region that is small compared to

the wavelength, particular states of the ensemble could radiate with an intensity proportional to the square of

the number of atoms. This is in contrast to normal radiance where the intensity of a sparse ensemble of two level

atoms is proportional to the number of atoms. This superradiance occurs due to the fact that a dense ensemble of

two level atoms interacts with a common reservoir, rather than an ensemble of individual reservoirs. The

reservoir can no longer distinguish which atom decayed and quantum interference between the many different

decay pathways can occur. This interference can enhance or reduce the emission intensity from the ensemble

leading to superradiance and subradiance respectively.

Following the work of Dicke, it was shown that superradiance can occur in a variety of systems including

multilevel atoms and harmonic oscillators when the ensemble decays into a common reservoir [2]. However,

despite over thirty years of superradiance experiments, harmonic oscillator superradiance has never been

experimentally observed. This is due to the difficulty of engineering a common reservoir interaction for an

ensemble of harmonic oscillators. We show that waveguide arrays in integrated photonics can be used to

engineer this common reservoir interaction and numerically simulate harmonic oscillator superradiance in these

arrays. We find that harmonic oscillator superradiance should be readily observed using existing technology.

Fig. 1: Waveguide geometry of proposed implementation. Light injected into the system waveguides (left semi-circle) will

undergo Markovian decay into the bath waveguides (right semi-infinite array).

References

[1] R. H. Dicke, Coherence in Spontaneous Radiation Processes, Phys. Rev. 93, 99 (1954).

[2] G. S. Agarwal, Quantum Statistical Theories of Spontaneous Emission and their Relation to Other Approaches, Springer Tracts in Modern Physics

70, 1, (1974).

128


Putting Even More Integration Into Integrated Quantum Photonics

Graham D. Marshall,1 Anthony Laing,2 Alberto Peruzzo,2 Alberto Politi,2

Jeremy L. O’Brien,2 Michael J. Withford1

1Centre for Ultrahigh bandwidth Devices for Optical Systems, MQ Photonics Research Centre, Department

of Physics and Astronomy, Macquarie University, North Ryde, NSW 2109, Australia 2Centre for Quantum Photonics, H. H. Wills Physics Laboratory & Department of Electrical and Electronic

Engineering, University of Bristol, Merchant Venturers Building, Woodland Road, Bristol, BS8 1UB, UK

Phone: +61-2-9850-7583


We demonstrate the direct-writing of Bragg-gratings into lithographically fabricated waveguide circuits. Our technique

enables wavelength selective filtering to be integrated into the existing and very successful silica-on-silicon ‘optical-chip’

platform used in quantum information science. The integration of filters directly on-chip will, we hope, improve the

performance of these circuits while reducing the overall complexity of the source and circuit systems.

The recent revolution in optical quantum information science (QIS) has been driven by the adaptation of

integrated optical circuitry as a replacement for bulk-optics setups that are limited in their scalability. Using

arrays of directional couplers (the integrated optics equivalent of the humble beam splitter) it is possible to

create quantum logic gates [1] and complex photonic circuits that can entangle and manipulate multiple photons

[2]. These ‘chip’ based circuits, and those that will follow in their stead, process the light from sources that create

two or more photons that are degenerate i.e.: identical in every way—they are of the same polarization, have the

same optical mode, they arrive at the same time, and importantly they have the same wavelength. Most of the

photon sources used in QIS experiments generate a broad bandwidth of photons and so a wavelength filtering

scheme is required to create identical photons ready for processing by the optical chips. Such filtering is

presently done in bulk optics using narrow-bandpass interference filters or in-fibre using Bragg gratings or other

telecommunications industry tools. In this work we are investigating the integration of wavelength filtering

devices into the silica-on-silicon photonic chip platform itself. Using a direct-write technique we have created

the first Bragg grating structures to be directly inscribed into a lithographically produced waveguide chip. Our

method is based on established techniques for the inscription of fibre-Bragg gratings [3] using the highly non-

linear interaction between a focused IR femtosecond laser beam and the fused silica material of the optical chip.

Fig. 1: Photograph of the pigtailed chip and (inset)

micrograph of the ~1 µm period grating

Fig. 2: The transmission and reflection spectra of the grating

An 8 mm long 2nd-order grating was written into a 3.5 µm² lithographically fabricated waveguide while being

simultaneously probed using a swept-wavelength system (Figure 1). The grating’s spectral response (Figure 2)

shows a narrow 16 dB rejection and reflection feature with additional cladding modes present in the

transmission spectrum. This result shows that it is possible to directly write strong gratings into the silica-on-

silicon chip platform and our investigations into other grating filter designs are continuing.

[1] A. Politi et al., “Silica-on-silicon waveguide quantum circuits,” Science 320(5876), pp. 646-649, (2008).

[2] P. J. Shadbolt et al., “Generating, manipulating and measuring entanglement and mixture with a reconfigurable photonic circuit,”

arXiv:1108.3309v1, (2011).

[3] G. D. Marshall et al., “Point-by-point written fiber-Bragg gratings and their application in complex grating designs," Optics Express, 18(19),

pp. 19844-19859 (2010).

129


Direct femtosecond-writing of Yb:ZBLAN waveguide lasers

Guido Palmer, Simon Gross, Alexander Fuerbach, David Lancaster and Michael Withford


Department of Physics and Astronomy, Macquarie University, Sydney

Phone: +61-2-9850-9078


Novel waveguide structures such as depressed ring-claddings have been investigated in Yb-doped ZBLAN glass towards

improved laser performance in integrated laser waveguides. Therefore the question will be addressed if waveguides written

in the cumulative heating regime by high repetition rates can provide better long term stability than waveguides previously

written with KHz-laser systems. Accordingly, first laser results of Yb:ZBLAN waveguides will be presented.

Throughout the last decade there has been a substantial commercial and scientific interest in integrated

waveguide lasers in various fields. This mainly owes to distinct properties such as a significant laser

miniaturization, efficient performance and high stability but also an excellent compatibility with other photonic

networks [1]. While different fabrication methods are established the direct writing of waveguides with

femtosecond pulses reveals the opportunity to directly create 3-dimensional structures in a single fabrication

step. Here the refractive index of the material is permanently altered in regions affected by the high laser

intensities. However for Yb-doped phosphate glass it has been shown that the waveguide laser structures

fabricated by means of laser systems with KHz-repetition rates tend to degrade with operation time [2]. Further

investigations revealed that this annealing of the waveguides is most likely due to absorption of the “blue” Yb-

co-operative luminescence by induced colour centers in the guides.

This work will focus on the improvement of long-term stability for waveguide lasers written with “faster” fs-

sources at MHz-repetition rates. The high repetition rates lead to cumulative heating where the change in

refractive index is based on different effects compared to the KHz-writing [3]. Many glass hosts exhibit a

negative change in refractive index under cumulative heating where light cannot be guided directly. However

by writing multiple negative structures around an unchanged centre according to Lancaster and Gross et al [4]

allows for the fabrication of low loss waveguides (3D-writing, Fig.1). The most promising material candidate for

this method is the utilized Yb:ZBLAN. Here uniform circular reproducible structures can be written. For

waveguide writing the laser pulses of a commercial fs-laser (Femtolaser: XL-500, repetition rate: 5.1 MHz, pulse

duration: 40 fs, pulse energy: 500 nJ) were focused via an 100 x immersion oil objective (Olympus) into the glass

samples which in turn, were moved through the writing-beam by a computer driven high-precision translation

stage (Aerotech). Embedding a 6-ring hexagon depressed cladding we could observe single mode guiding for

both the pump wavelength at 980 nm and the laser wavelength from 1030 – 1060 nm. Core diameters from 9 to

14 μm yielded mode field diameters (MFD) around 13 μm. First laser results will be presented at the workshop.

Fig.1: Depressed cladding waveguide (a) and according MFD-image (b) at 980 nm

References:

[1] Christos Grivas, “Optically pumped planar waveguide lasers, Part I: Fundamentals and fabrication techniques,” Progress in Quantum Electronics

Vol. 35 (2011) 159–239

[2] P. Dekker, M. Ams, G. D. Marshall, D. J. Little and M. J. Withford, “Annealing dynamics of waveguide Bragg gratings: evidence of femtosecond

laser induced colour centres,” Opt. Exp. Vol.18, 3274—3283 (2010)

[3] Douglas J. Little, Martin Ams, Simon Gross, Peter Dekker, Christopher T.Miese, Alex Fuerbach and Michael J. Withford, “Structural

changes in BK7 glass upon exposure to femtosecond laser pulses,” J. Raman Spectrosc. (2010)

[4] D. G. Lancaster, S. Gross, H. Ebendorff-Heidepriem, K. Kuan, T. M. Monro, M. Ams, A. Fuerbach, and M. J. Withford, “Fifty percent

internal slope efficiency femtosecond direct-written Tm3+:ZBLAN waveguide laser,” Opt. Lett. Vol. 36, 1587—1589 (2011)

130


Near-field probing of slow Bloch modes on photonic crystals with a nanoantenna

Thanh-Phong Vo1,5*, M. Mivelle3, S.Callard1, A. Rahmani2, F. Baida3, D.

Charraut3, A. Belarouci1, D. Nedeljkovic4, C.Seassal1, G.W. Burr5, T. Grosjean3 1Universite de Lyon, Institut des nanotechnologies de Lyon INL-UMR 5270,CNRS, Ecole

Centrale de Lyon, Avenue Guy de Collongue, F-69134 Cedex, France 2School of Mathematical Sciences, University of Technology, Sydney, NSW 2007, Australia

3Departement d’Optiq e P.M. D ffie x, Instit t FEMTO-ST, UMR CNRS 6174, Universite de

Franche-Comte, 16 route de Gray, 25030 Besanon cedex, France 4Lovalite s.a.s.,18 rue Alain Savary, 25000 Besanon



Phone: (+61) 02 98 50 41 64


We report on near-field investigation of the Slow Bloch Mode (SBM) associated with the Г-point of the Brillouin zone for an

active honeycomb lattice photonic crystal using Near-field scanning optical microscopy (NSOM). Bowtie-aperture

nanoantenna (BAN) tip based NSOM provides the near-field optical images of these modes with the higher spatial

resolution (λ/20) and enhanced collection efficiency (two orders of magnitude) compared to the conventional ones.

The high sensitivity of the BAN to the electric field and its polarization filtering properties have been

demonstrated recently [1-3]. Therefore the BAN-based optical near-field probes might yield a high spatial

resolution and enhanced collection efficiency compared to conventional, metal coated optical fiber probes. Their

abilities to discriminate between near-field polarization states on a sub-wavelength scale was experimentally

demonstrated by measuring the SBM spatial profile associated at the Γ–point of honeycomb photonic crystal [4-

5] and comparing it to 3D FDTD simulations. An excellent agreement was found which highlights the fact that

the BAN near-field probe does not generate any significant perturbation of the optical mode of the photonic

crystal. We have also proved that the BAN can overcome one of the main limitations of NSOM, linked to the

well-known trade off between resolution and signal-to noise ratio.

Figure: (a) SEM image of bowtie aperture nano-antenna engineered at the apex of a polymer tip. Scaling bar is 200nm. (b)

and (c) the optical images of E2x and E2y-components of SBM in unit cells (white circles) respectively.

In future studies, the coupling of BAN probes with heterodyne detection SNOM would allow for the full

vectorial characterization of optical modes at the surface of PCs, for both the electric and magnetic fields. The

present investigation also paves the way for emerging nanophotonic architectures aiming at integrating

nanoantennas [6] on top of a PC resonator. Nanoantenna-on-fiber devices could also be seen as an optimized

interface for out-coupling optical energy from PC structures toward fiber networks.

[1] L. Novotny and B. Hecht, Principle of Nano-Optics (Cambridge University Press, 2006).

[2] L. Wang and X. Xu,“High transmission nanoscale bowtie-shaped aperture probe for near-field optical imaging,”Appl.Phys.Lett.90 (2007).

[3] M. Mivelle, I. A. Ibrahim, F. Baida, G. W. Burr, D. Nedeljkovic, D. Charraut, J.-Y. Rauch, R. Salut, and T. Grosjean, “Bowtie nano-aperture

as interfacebetween near-fields and a single-modefiber,” Opt. Exp. 18, 15964–15974 (2010).

[4] J. Joannopoulos, S. Johnson, J. Winn, and R. Meade, Photonic Crystals: Molding the Flow of Light (Second Edition) (Princeton University

Press, 2008).

[5] T.-P. Vo, A. Rahmani, A. Belarouci, C. Seassal, D. Nedeljkovic, and S. Callard, “Near-field and far-field analysis of an azimuthally

polarized slow bloch mode microlaser,” Opt. Exp. 18, 26879–26886 (2010).

[6] M. Barth, S. Schietinger, S. Fischer, J. Becker, N. Nüsse, T. Aichele, B. Löchel, C. Sönnichsen, and O. Benson, “Nanoassembled

plasmonic-photonic hybrid cavity for tailored light-matter coupling,” Nano Lett. 10, 891–895 (2010)

b) c)


131


Super-resolution photoinduction-inhibited nanofabrication based on the two-photon

absorption process

Yaoyu Cao1, Zongsong Gan 1, Richard A. Evans 2, and Min Gu 1

1Centre for Micro-Photonics and Centre for Ultrahigh bandwidth Devices for Optical Systems

(CUDOS), Faculty of Engineering and Industrial Science, Swinburne University of Technology,

Hawthorn, VIC 3122 2CSIRO Molecular and Health Technologies, Clayton South, Victoria 3169

Phone: (03)92144735


We demonstrate the SPIN technique based on two-photon absorption process, which is able to produce the dot and the line

of the feature size of 33 nm and 32 nm, equal to /24 and /25, respectively.

The emerging super-resolution photoinduction-inhibtited nanofabrication technique (SPIN) has demonstrated

impressive feature size reduction down to the nano-scale in the field of the direct laser writing. The key idea is to

introduce a second laser beam with a Gauss-Laguerre “doughnut” mode to locally inhibit the resist

polymerisation. With employing the process of the photogeneration of inhibitor radicals [1], the feature size of

40 nm has been realized in the single-photon SPIN technique [2] by fabricating dots on the cover slip. However,

it has inherent drawbacks in the fabrication of three-dimensional structures.

As for the two-photon fabrication technique, which is well known for its ability in the fabrication of three-

dimensional mircostructures, there exists a great material challenge to achieve photoinitiation and

photoinhibition simultaneously in the photoresist by the irradiation of the inhibiting laser beam and the

initiating beam. In this paper, we demonstrate the SPIN technique based on two-photon absorption process. We

applied a femtosecond pulsed laser beam at a wavelength of 800 nm to initiate the polymerisation and a CW

laser beam at a wavelength of 375 nm to activate the inhibitor. In this case, we have achieved dots of 33 nm and

lines of 32 nm, which is 1/24 and 1/25 of the wavelength of the initiating laser beam, respectively, as shown in

Fig. 1.

Figure 1 (a) Dot sizes are plotted as a function of the exposure time. (b) The SEM image of polymer dots fabricated with the

exposure of initiating laser and inhibiting laser beams of the power levels of 15 mW and 0.6 W, respectively, at the exposure

time of 10 ms. (c) Linewidths are plotted as a function of the scanning speed. (d) The SEM image of polymer lines fabricated

with the exposure of initiating laser and inhibiting laser beams of the power levels of 18 mW and 0.6 mW, at the scanning

speed of 140 m/s.

References [1] T. F. Scott, B. A. Kowalski, A. C. Sullivan, C. N. Bowman, and R. R. Mcleod, “Two color single photon photoinitiation and photoinhibition for

subdiffraction photolithography”, Science, 324, 913, (2009).

[2] Y. Y. Cao, Z. S. Gan, B. H. Jia, R. A. Evans and M. Gu, “High-photosensitive resin for super-resolution direct-laser-writing based on photoinhibited

polymerization”, Opt. Express, 18, 19486, (2011).

a b

50 nm

33nm

c d


132


Functional three-dimensional nonlinear nanostructures in gold ion nanocomposite

Baohua Jia, Dario Buso, Zhengguang He, Min Gu

Center for Micro-Photonics and CUDOS, Swinburne University of Technology,

John Street Hawthorn, Victoria 3122, Australia


We developed a novel nanocomposite consisting of an organic-inorganic hybrid polymer and gold ion nanoparticles. The

nanocomposite is suitable for functional three-dimensional nanostructure fabrication due to the dominant formation of the

nanoparticles triggered in the post bake process after nanofabrication. The nanocomposite has high third-order nonlinearity

due to the localised field enhancement of the gold nanoparticles.

Organic-inorganic hybrid polymers have been demonstrated to be promising materials for multi-photon

fabrication of functional miniaturized photonic structures [1-3]. The incorporation of highly nonlinear gold

nanoparticles can transform the plain polymer into a multi-functional active medium thus opening various

possibilities for achieving novel active photonic devices [4]. Gold nanoparticles are well-known for their large

third-order nonlinearity attributed to the plasmonic enhancement of the localised field [5]. Nanocomposites

incorporated with metal nanoparticles have been reported extensively [6], but highly nonlinear photosensitive

nanocomposites suitable for two-photon polymerization (2PP) has not yet been established.

In this paper, we demonstrate the functionalization of the organic-inorganic polymer, namely Ormocer, by

incorporation of gold ion nanoparticles. It has been shown (Fig. 1) through the open and close aperture Z-Scan

measurement that the nanocomposites have ignorable two-photon absorption at the investigated wavelength

but possess Ultrahigh Kerr nonlinearity when annealed after the fabrication process to form gold nanoparticles.

The nonlinear nanocomposite has been proven to be suitable for the fabrication of three-dimensional (3D)

micro/nano photonic device using the 2PP method, as shown in Fig. 1.

Fig. 1: (a) SEM image of the fabricated 3D photonic crystal in the nanocomposites. (b) TEM image of the gold nanoparticle

formation inside the nanocomposites. (c) Close aperture Z-scan measurement of the nonlinear refraction of the

nanocomposite.

References 1. J. Serbin, A. Egbert, A. Ostendorf, B.N. Chichkov, R. Houbertz, G. Domann, J. Schulz, C. Cronauer, L. Frohlich, and M. Popall,

Femtosecond laser-induced two-photon polymerization of inorganic-organic hybrid materials for applications in photonics. Opt. Letts. 28.

301-303, (2003).

2. B. Jia, J. Li and M. Gu, “Two-photon polymerisation for three-dimensional photonic devices in polymer and nanocomposites,” Australian

Journal of Chemistry, 60, 484-495 (2007).

3. J. Li, B. Jia, G. Zhou, J. Serbin, C. Bullen, M. Gu, “Spectral redistribution in spontaneous emission from quantum-dot-infiltrated 3D

woodpile photonic crystals for telecommunications,” Adv. Mater. 19, 3276-3280 (2007).

4. B. Jia, D. Buso, J. van Embden, J. Li and M. Gu, “Highly Non-Linear Quantum Dot Doped Nanocomposites for Functional Three-

Dimensional Structures Generated by Two-Photon Polymerization,” Adv. Mater. 22 (22), 2463 - 2467 (2010).

5. P. Lu, K. Wang, H. Long, M. Fu, and G. Yang, "Size-related third-order optical nonlinearities of Au nanoparticle arrays," Opt. Express 18,

13874-13879 (2010), http://www.opticsinfobase.org/abstract.cfm?URI=oe-18-13-13874C.

6. Masanori Sakamoto, Takashi Tachikawa, Mamoru Fujitsuka, and Tetsuro Majima, “Photochemical Formation of Au/Cu Bimetallic

Nanoparticles with Different Shapes and Sizes in a Poly(vinyl alcohol) Film,” Adv. Funct. Mater. 17, 857–862 (2007).

133


Selective silver coating for nanoplasmonic structures

Elisa Nicoletti, Mark D. Turner, and Min Gu


Centre for Micro-Photonics, Faculty of Engineering of Industrial Sciences, Swinburne University of

Technology

Phone:


We report on selective silver deposition over polymer that can be used to realize complex nanoplasmonic structures. An

electroless silver coating method is used to deposit a thin silver film onto sensitized polymeric structures while the glass

slide is covered with a hydrophobic thin film to avoid silver coating of the substrate.

A lot of interest has recently arisen in plasmonic devices due to their unique properties of extreme light

localisation and light-emission enhancement from active photonic devices via coupling to surface plasmons

(SPs). A number of applications have been recently demonstrated in different fields, including plasmonic

waveguides [1], nanocircuits [2], switching devices [3], nanoantennas [4], and photovoltaic devices [5].

Considerable effort has been concentrated in fabrication of high quality metallic nanostructures. However to be

able to truly explore and exploit the unique properties of the nanoplasmonic structure the surface chemistry

should be selective.

Here we report on a selective metallization protocol that can be applied to polymeric structures with arbitrary

geometries. The fabrication process consists in different steps described in Fig. 1.

A hydrophobic film is deposited on the substrate by dip-coating (Fig. 1(a)). The photoresist (IP-L) is dropped

onto the substrate and patterned via direct laser writing (DLW) (Fig. 1(b)). The polymer surface is activated by

dipping in a solution of SnCl2 in EtOH to improve the metal deposition and adhesion (Fig. 1(c))[6]. The dielectric

template was coated with a thin layer of metal silver film via electroless silver plating (Fig. 1(d)). Fig. 1 (e) show

a drop of IP-L coated with silver on the hydrophobic substrate. The metal is deposited homogeneously on the

IP-L surface without coating the substrate.

Fig. 1 Schematic illustration of the realization of nanoplasmonic structures on a transparent substrate. a) Deposition of the

hydrophobic film by dip-coating. b) Fabrication of the structures by two photon polymerization (TPP). c) Activation of the

polymeric surface with SnCl2. d) Electroless silver plating. e) Photo of a drop of IP-L selectively coated.

References 1. Maier, S.A., et al., Plasmonics - A route to nanoscale optical devices. Advanced Materials, 2001. 13(19): p. 1501-1505.

2. Engheta, N., Circuits with light at nanoscales: Optical nanocircuits inspired by metamaterials. Science, 2007. 317(5845): p. 1698-1702.

3. Onuki, T., Y. Ohtera, and T. Tokizaki, Study of surface plasmon polaritons near the photonic-bandgap edge for interphotonic band

switching devices. Journal of Microscopy, 2008. 229(3): p. 447-451.

4. Large, N., et al., Photoconductively loaded plasmonic nanoantenna as building block for ultracompact optical switches. Nano Letters,

2010. 10(5): p. 1741-1746.

5. Atwater, H.A. and A. Polman, Plasmonics for improved photovoltaic devices. Nature Materials, 2010. 9(3): p. 205-213.

6. Radke, A., et al., Three-dimensional bichiral plasmonic crystals fabricated by direct laser writing and electroless silver plating. Advanced

Materials, 2011.

e) a) c) b) d)

134


Optimisation of super-resolution photo induction-inhibited nanolithography

Michael James Ventura, Yaoyu Cao, Zongsong Gan, and Min Gu


Centre for Micro-Photonics, Swinburne University of Technology

Phone: 03 9214 5181


In this paper we present experimental optimization of a super-resolution photo induction-inhibited nanolithography system.

Super-resolution photo induction-inhibited nanolithography (SPIN) is an all optical technique allowing for the

fabrication of three-dimensional arbitrary structures with nanoscale resolution [1]. Using optical principles

established in stimulated emission depletion imaging microscopy [2], SPIN achieves fabrication optical

resolutions beyond the diffraction limit. The combination of specialised optical materials and structured foci,

SPIN can generate features on the order of λ/24. SPIN materials consist of specific ratios of photo-inductors,

photo-inhibiters and monomers, optimised for mechanical strength and photostability. Photo-polymerisation,

the conversion of the monomer to a stable polymer is initiated by the photo-inductor and suspended by the

photo-inhibitor. By spatially overlapping a diffraction limited point spread function that induces

polymerisation with a donut beam which terminates the polymerisation process, SPIN fabrication is achieved.

To achieve resolution of tens of nanometers in three-dimensions using SPIN requires precise control over many

experimental parameters. Mechanical stability, optical alignment, and laser stability must all be optimised and

maintained through the fabrication process. Optimisation of optical parameters, including power, exposure and

wavelength have been conducted resulting in a parameter window that allows for the fabrication of

mechanically stable, free standing three-dimensional elements beyond the diffraction limit.

Fig. 1: Schematic diagram of SPIN setup. Visible achromatic doublets (L1,L2,L5,L6); UV AR-coated double convex lenses

(L3,L4); Mechanical shutters (S1, S2); Neutral density filters (ND1, ND2); Spatial filtering pinholes (P1-P3); Phase plate (PP);

Broadband mirror (M1, FM1); Color glass filter (CF); Dichroic mirrors (DC1, DC2); Charged coupled device (CCD).

References [1] Y. Cao, Z. Gan, B. Jia, R. A. Evans, and M. Gu, "High-photosensitive resin for super-resolution direct-laser-writing based on photoinhibited

polymerization," Opt. Express 19, 19486-19494 (2011).

[2] S. W. Hell, and J. Wichmann, "Breaking the diffraction resolution limit by stimulated emission: stimulated-emission-depletion fluorescence

microscopy," Optics Letters 19, 780-782 (1994).


135


Circular Dichroism in Biological Photonic Crystals & Cubic Chiral Nets

G. E. Schröder-Turk1, M. Saba1, M. Thiel2, M. D. Turner3, S. T. Hyde4, M. Gu3, K. Grosse-

Brauckmann5, D. N. Neshev6, and K. Mecke1 1 Theoretische Physik, University Erlangen, 91058 Erlangen, Germany

2 Center for Functional Nanostructures, Karlsruhe Institute of Technology, Karlsruhe, Germany 3 Centre for Micro-Photonics & CUDOS, Swinburne University of Technology, VIC 3122, Australia

4 Applied Mathematics, Research School of Physics & Eng, Australian National University, ACT 5 Fachbereich Mathematik, Technische Universität Darmstadt, 64289 Darmstadt, Germany

6 Nonlinear Physics Centre, Research School of Physics & Eng., Australian National University,

ACT

Phone: +49 175 9265792


Nature provides impressive examples of chiral photonic crystals, with the notable example of the cubic so-

called srs network (the label for the chiral degree-three network modeled on SrSi2) or gyroid structure realized

in wing scales of several butterfly species [1]. By a circular polarization analysis of the band structure of such

networks, we demonstrate strong circular dichroism effects [2]: The butterfly srs microstructure, of cubic I4132

symmetry, shows significant circular dichroism for blue to ultraviolet light, that warrants a search for biological

receptors sensitive to circular polarization. A derived synthetic structure based on four like-handed silicon srs

nets exhibits a large circular polarization stop band of a width exceeding 30%. These findings offer design

principles for chiral photonic devices, some of which have been realised by direct laser writing [3].

Fig. 1: (Left) Gyroid constant-mean curvature network realised in chitin wing-scales of butterfly C. rubi. (Middle)

Photograph of C. rubi and electron micrographs of its wing-scales. (Right) Structure composed of four interthreaded

Gyroid/srs nets.

References

[1] G.E. Schröder-Turk, S. Wickham, H. Averdunk, F. Brink, J.D. Fitz Gerald, L. Poladian, M.C.J. Large, S.T. Hyde, “The chiral structure of

porous chitin within the wing-scales of Callophrys rubi”, J. Struct. Biol. 174, 290-295 (2011).

[2] M Saba, M. Thiel, M.D. Turner, S.T. Hyde, M. Gu, K. Grosse-Brauckmann, D.N. Neshev, K. Mecke, and G.E. Schröder-Turk, “Circular

Dichroism in Biological Photonic Crystals and Cubic Chiral nets”, Phys. Rev. Lett 106, 103902 (2011).

[3] M Turner, G.E. Schröder-Turk, and M. Gu, “Fabrication and characterization of three-dimensional biomimetic chiral composites”, Optics

Express 19(10), 10001 (2011).

136

SELECTED PRESENTER PROFILES

Igal Brener obtained his B.A. in Physics, B.Sc. in Electrical Engineering and D.Sc. in Physics

from the Technion, Haifa, Israel. He has held the position of Nanophotonics Thrust Leader,

Center for Integrated Nanotechnologies at Sandia National Laboratories, Albuquerque,

since 2008.

Igal's research at CINT deals with fundamental and applied aspects of metamaterials,

plasmonics and related nanophotonics phenomena. Recent examples include novel

metamaterial designs in the infrared (active and passive), the integration of

nanoparticles and nanofabricated photonic structures, uses of plasmonics and

metamaterials in sensing, and the control of emission and absorption of light at the

nanoscale. For his research, he uses extensively the nanofabrication facilities and a

variety of spectroscopic techniques (linear, non-linear and time-resolved) all available at

CINT. He also contributes to the development of new optical instrumentation such as

broadband THz and superresolution optical microscopies.

Alfredo De Rossi graduated from the University of Rome, Italy in 1997. Since 2000 he has

been with Thales Research and Technology (Thales Corporate Research Laboratory)

where he has been working in nonlinear optics, semiconductor photonic devices,

infrared detectors and lasers. The present focus of his research is on photonic crystals for

all-optical processing. Alfredo is author of about 70 papers and is named on more than

10 patents.

Shanhui Fan is an Associate Professor of Electrical Engineering at the Stanford University.

He received his Ph.D. in 1997 in theoretical condensed matter physics from the

Massachusetts Institute of Technology (MIT), and was a research scientist at the Research

Laboratory of Electronics at MIT prior to his appointment at Stanford. His research interests

are in computational and theoretical studies of solid state and photonic structures and

devices, especially photonic crystals, plasmonics, and meta-materials. He has published

over 230 refereed journal articles that were cited near 14,400 times, has given over 180

invited talks, and was granted 39 US patents. Dr. Fan is a Fellow of IEEE, APS, OSA and

SPIE. He received a National Science Foundation Career Award (2002), a David and

Lucile Packard Fellowship in Science and Engineering (2003), the National Academy of

Sciences Award for Initiative in Research (2007), and the Adolph Lomb Medal from the

Optical Society of America (2007).

Wolfgang Freude received the Dipl.Ing. (M.S.E.E.) and the Dr.Ing. (Ph.D.E.E.) degrees in

Electrical Engineering from the University of Karlsruhe, respectively, and was awarded an

Honorary Doctorate of Kharkov National University of Radioelectronics, Ukraine. He is

Professor at the Institute of Photonics and Quantum Electronics, at the Institute of

Microstructure Technology, and in the Network of Excellent Retired Scientists, Karlsruhe

Institute of Technology (KIT). His research activities are in the area of optical high-data

rate transmission, high-density integrated-optics with a focus on silicon photonics,

photonic crystals and semiconductor optical amplifiers, and in the field of low-energy

opto-electronic devices and protocols for optical access networks. He has published

more than 200 papers, delivered more than 240 lectures in Germany and abroad, and

authored or coauthored a book and three book chapters on optical communications,

multimode fibres, photonic crystals and semiconductor optical amplifiers. He is a member

of OSA, IEEE, and VDE.

137


John Harvey has a Ph.D. in Theoretical Physics from the University of Surrey (UK). He is

presently Professor of Physics at the University of Auckland and a Principal of Southern

Photonics, a company that has developed a reputation over the last five years for

building innovative instrumentation for high speed telecommunications research. He has

worked in a variety of areas encompassing Laser Physics, Cell Biology, Biochemistry and

Engineering. Since 1990 his research work has moved increasingly into laser physics and its

applications, particularly in telecommunications with a continuing interest in other

biophysical projects. Recent work is concentrated in the area of nonlinear fibre optics,

and high speed optical communications systems and devices. His group will collaborate

with CUDOS to develop novel instrumentation based around chalcogenide fibres.

Ortwin Hess holds the Leverhulme Chair in Metamaterials in the Department of Physics at

Imperial College London and is Co-Director of the Centre for Plasmonics & Metamaterials.

Ortwin studied physics at the University of Erlangen and the Technical University of Berlin.

Following pre- and post-doctoral times in Edinburgh and at the University of Marburg

Ortwin has been (from 1995 to 2003) Head of the Theoretical Quantum Electronics Group

at the Institute of Technical Physics in Stuttgart, Germany. He has a Habilitation in

Theoretical Physics at the University of Stuttgart (1997) and became Adjunct Professor in

1998. Since 2001 he is Docent of Photonics at Tampere University of Technology in Finland.

Ortwin has been Visiting Professor at Stanford University (1997 - 1998) and the University of

Munich (2000 - 2001). From 2003-2010 he held the Chair of Theoretical Condensed Matter

and Optical Physics in the Department of Physics and the Advanced Technology Institute

at the University of Surrey in Guildford, UK where he is now a Visiting Professor.

Ortwin’s research interests and activities are focused on metamaterials, nano-plasmonics

and quantum photonics.

David Miller received a B.Sc. in Physics from St. Andrews University, and performed his

graduate studies at Heriot-Watt University where he was a Carnegie Research Scholar.

After receiving the Ph.D. degree in 1979, he continued to work at Heriot-Watt University,

latterly as a Lecturer in the Department of Physics. He moved to AT&T Bell Laboratories in

1981 as a Member of Technical Staff, and from 1987 to 1996 was a Department Head,

latterly of the Advanced Photonics Research Department. He is currently the W. M. Keck

Foundation Professor of Electrical Engineering at Stanford University, and is Director of the

the Solid State and Photonics Laboratory at Stanford, and a Co-Director of the Stanford

Photonics Research Center. He also served as the Director of the E. L. Ginzton Laboratory

at Stanford University from 1997-2006.

He is a Member of the National Academy of Sciences and of the National Academy of

Engineering, a Fellow of the Royal Society of London, the Royal Society of Edinburgh, the

IEEE, the Optical Society of America and the American Physical Society. He was awarded

the 1986 Adolph Lomb Medal of the OSA, was co-recipient of the 1988 R. W. Wood

Medal, and received the 1991 Prize of the International Commission for Optics.

Nikitas Papasimakis completed his undergraduate studies in the Physics Department of

the Athens National University, Greece in 2005 and his Ph.D. studies in the Optoelectronics

Research Centre at the University of Southampton in 2009. In the same year, he was

awarded a Ph.D. Plus fellowship to continue his research as a postdoctoral fellow and in

2010 he was appointed Leverhulme Advanced Research Fellow at the same institution.

His current research focus is on Planar Metamaterials.

http://www3.imperial.ac.uk/plasmonmeta

138


Michaël Roelens completed his Ph.D. in Optoelectronics at the University of Southampton

in 2006, and then joined CUDOS to work with Prof. Eggleton at the University of Sydney on

the initial ARC linkage project with Optium (now Finisar). In this project he successfully

adapted the Wavelength Selective Switch technology into a multi-functional optical

pulse shaper.

He moved to Finisar in 2008, where he commercialised this device (WaveShaper) and

now heads the engineering team in the Optical Instrumentation Group. He continues to

collaborate with Dr. Schröder at CUDOS during the second Linkage project, in which the

advanced high speed test bed at the University of Sydney is used to develop novel

approaches for simulating, measuring and compensating impairments on coherent

modulation formats, such as DPSK signals. For 2012-2015, a third ARC linkage project has

been funded to expand the technology into the field of modal switching.

Gunther Roelkens was born in Ghent, Belgium, in 1979. He received a degree in electrical

engineering from Ghent University, Belgium, in 2002 and a Ph.D. from the same university

in 2007, at the Department of Information Technology (INTEC), where he is currently a

tenure track research professor. In 2008, he was a visiting scientist in IBM TJ Watson

Research Center, New York. He is currently also part-time assistant professor at Eindhoven

University of Technology, The Netherlands.

His research interest includes the heterogeneous integration of III-V semiconductors and

other materials on top of silicon waveguide circuits, for high performance photonic

integrated circuits. Currently he is holder of an ERC starting grant (MIRACLE), to start up

research in the field of integrated mid-infrared photonic integrated circuits. He has

published over 40 journal papers and holds several patents. He is a member of IEEE

Photonics Society.

John Sipe currently holds the position of Professor, Department of Physics at the University

of Toronto and is a Partner Investigator in CUDOS. His expertise is in the areas of

theoretical physics of quantum and nonlinear optics, optical and spin properties of

semiconductors, and the optical properties of artificially structured materials.

His current research focuses on coherent control and transport of carriers, spins, currents,

and spin currents in bulk and nanostructure semiconductors: optical properties of ring

resonators and other artificially structured materials, and their use in quantum and

nonlinear optics; application of structures with optical resonances to problems in

biosensing; foundational problems in quantum mechanics.

Mark Thompson is a lecturer and researcher fellow at the University of Bristol within the

departments of Physics and Electrical Engineering. He holds a master degree in Physics

from University of Sheffield and a Ph.D. in Electrical Engineering from the University of

Cambridge. Prior to his Ph.D. he was a researcher scientist at Bookham Technology Inc

developing silicon-based integrated photonic components for the telecommunications

industry. His Ph.D. studies focused on semiconductor laser dynamics and ultra-short pulse

generation in quantum-dot mode-locked lasers diodes, and in 2006 he was appointed a

research fellowship position at the University of Cambridge. He won the 2009 Toshiba

Fellowship award and held a visiting researcher position at the Toshiba research

headquarters in Japan, developing silicon photonic components for computing

applications. Since 2008 he has held a permanent position at the University of Bristol

where he leads a team of researchers developing integrated quantum photonic

technologies. He has been involved in many national and international projects, and is

coordinator of the EU-FP7 project QUANTIP”.

Workshop Handbook Project Presenstations and Poster Abstracts … version.pdf · Co-Director Stanford Photonics Research Centre W. M. Keck Foundation Professor of Electrical Engineering,

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