Enhancing performance of metre-class telescopes by using ... · using photonic devices Nemanja Jovanovic, Simon Gross, Robert Williams, Michael Ireland, Jon Lawrence, and Michael

Enhancing performance of metre-class telescopes by

using photonic devices

Nemanja Jovanovic, Simon Gross, Robert Williams, Michael Ireland, Jon Lawrence, and Michael Withford

MQ Photonics Research Centre, Department of Physics and Astronomy, Macquarie University

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

University Australian Astronomical Observatory (AAO)

National Astronomical Observatory of Japan, Subaru Telescope1

Izabela Spaleniak

Outline

• (Some) Photonics in astronomy• Photonic lanterns• Photonic lanterns as spectral filters

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Photonics in astronomy• Astrophotonics: lies at the interface

between astronomy and photonics• Photonics: manipulating photons• Multimode fibres

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Optical fibre – principle• Single-mode fibre • Multimode fibre

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Photonics in astronomy

• Integrated photonic spectrograph

N. Cvetojevic et al. Opt. Express 20, 2062-2072 (2012).

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Photonics in astronomy

• IPS on sky

The H-Band spectrum of Pi 01 Gru, with a cut showing the CO molecular lines. N. Cvetojevic et al. A&A 544 (2012).

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Photonics in astronomy• Frequency combs

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Photonics in astronomy• Fibre Bragg gratings

2B effnλ = × Λ

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Photonics in astronomy• Fibre Bragg gratings – GNOSIS instrument

• Knocks-out 103• Complex

• λB temperature sensitive

C. Trinh et al. A&A 544 (2012).

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Photonics in astronomy

• GNOSIS on sky

Spectrum of the night sky with (black) and without (red) OH suppression. The spectrum comes from 21 exposures (8.75 hr total) from 1-4 September at various locations on the sky. The reduction in the OH lines in the range 1.5-1.7 micron is clear showing the CO molecular lines. C. Trinh et al. A&A 544 (2012).

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Photonics in astronomy• Photonic devices accept only single-

mode light

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Adaptive optics

correction

wavefront profile after coming

through atmosphere

Diffraction limited (single-mode) instrument

?

How to overcome the atmosphere…

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… expensive, not fast enough for the visible, small angle

Adaptive optics

correction

wavefront profile after coming

through atmosphere

Diffraction limited (single-mode) instrument

Seeing-limited to diffraction-limited image conversion

?

Single mode spectrograph: compact, stable, cheap(er)

How to overcome the atmosphere…

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… expensive, not fast enough for the visible, small angle

Fibre photonic lantern

• Operates in 1550 nm • 7, 19 or 61 channels

D. Noordegraaf, et al., "Multi-mode to single-mode conversion in a 61 port Photonic Lantern." Opt. Express, 18(5): p. 4673-4678 (2010)

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Challenges of moving to visible

2

⋅≈

λθseeingtelD

Nm

Anglo-Australian Telescope siteθSeeing = 1”; Dtel = 3.9 m; Nm(λ = 1550 nm) ≈ 148Nm(λ = 600 nm) ≈ 993Nm(λ = 400 nm) ≈ 2234

Number of modes due to atmosphere :

Bulky Temperature sensitive Complex to make Complex to handle

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Laser direct write technique

glass sample

moving stage

laser beamwaveguides

objective lens

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Laser direct write technique

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Integrated photonic lanterns

Thomson, R., et al., Optics Express, 19, 6, 5698-5705 (2011)

Thomson, R., et al., Optics Letters, 37, 12, 2331-2333 (2012)

Losses: 2 dB Losses: 7 dB

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MM input

Transition

SM reformatted output

Isolated SM waveguides

Design of high throughput structures

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Jovanovic, N., et al., Proc. of SPIE, 7739-73, (2010).

1.1 MM input waveguides – old results

Design of high throughput structures

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Design of high throughput structures1.2 MM input waveguides – new approach

Jovanovic, N., et al., Opt.Express 20, 17029–17043 (2012).

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2. Modelling different transitionsa)Transition geometry

Linear Raised Sine Cosine

b) Transition length

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Design of a high throughput structure

MM inputTransition

Modelling results

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>90% transmission for a transition length >5 mm

Fabricated devices

50 µm

50 µm

Direction of writing laser

Writing parameters:Objective: 100x, NA 1.25Pulse energy: 35 nJTranslation speed: 750 mm/min (2 s per waveguide)

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Experimental throughput results

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Transition length

Experimental throughput results

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Multimode pitch

Slit reformatting devices

Dispersion directionSM slit

MM guide

Isolated SM guides

Slit of SM guides

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Slit reformatting devices – results

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OH suppression with integrated photonic lanterns

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OH suppression with integrated photonic lanterns – design

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OH suppression with integrated photonic lanterns – results

Efficient and symmetrical gratings in the photonic lantern Robust Easy to handle Stronger gratings possible in longer chips Application in a post-dispersion low resolution spectrographs

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On-going work

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Single-mode bulk spectrograph – RHEA – Small, stable, cheap (Mike Ireland & Tobias Feger)

Visible photonic lanterns

Many tiny (~4 um) waveguidesAnnealing technique

A. Arriola et al. Opt. Express 21, 2978-2986 (2013).

Summary• Integrated photonic lanterns are

potentially most scalable solution for photonic lanterns

• High efficiency can be obtained if you optimize the devices

• Promising results for miniaturising seeing-limited to diffraction-limited conversion devices.

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Thanks and acknowledgments

This research was supported by the Australian Research Council Centre of Excellence for Ultrahigh Bandwidth Devices for Optical Systems (project number CE110001018).

This work was performed in part at the OptoFab node of the Australian National Fabrication Facility, ANFF.

Nemanja Jovanovic, Simon Gross,

Nick CvetojevicMichael Ireland, Jon Lawrence,

and Michael Withford

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