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Nanofiber Coupled Nanoplasmonics
Limin Tong State Key Laboratory of Modern Optical Instrumentation
College of Optical Science and EngineeringZhejiang University, Hangzhou, China
KITPC Program “Plasmonic Nanogaps and Circuits” , October 12-30, 2015, Beijing
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Outline
1. Introduction
2. Nanofiber coupled nanowire plasmonics
3. Nanofiber coupled nanorod plasmonics
4. Conclusion
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Outline
1. Introduction
2. Nanofiber coupled nanowire plasmonics
3. Nanofiber coupled nanorod plasmonics
4. Conclusion
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1. Introduction Nanoplasmonics in Metallic Nanostructures
Unique optical properties to enable routing and active manipulation of light at the nanoscale, and to bridge photonics and nanoelectronics.
M. L. Brongersma et al., Science 328, 440 (2010)
Special advantages
Size and Speed
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http://nano.imra.com/
Size and Speed
Nano Lett. 9, 4515 (2009)
Nanosphere Nanorod Nanowire
Typical low-D metal nanostructures for nanoplasmonics
1. Introduction
0-D 1-D
Nano Lett. 12, 3145 (2012)
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http://nano.imra.com/
Size
Nano Lett. 9, 4515 (2009)
Nanosphere Nanorod Nanowire
Typical low-D metal nanostructures for nanoplasmonics
1. Introduction
0-D 1-D
Nano Lett. 12, 3145 (2012)
Size Optical confinementDeep subwavelength /10 /50 @ 700 nm
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http://nano.imra.com/
Size
Nano Lett. 9, 4515 (2009)
Nanosphere Nanorod Nanowire
Typical low-D metal nanostructures for nanoplasmonics
1. Introduction
0-D 1-D
Nano Lett. 12, 3145 (2012)
Y. P. Wang et al.,Opt. Express 20, 19006
(2012)
Size Optical confinementDeep subwavelength /10 /50
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Au nanowireMode size diameter beam size possibly down to a single-molecule level
Optical confinement
Modal profiles of Au nanowires in water (a) 10 nm; (b) 20 nm @ 660 nm
In air
In water
Mode size 10 nm
Y. P. Wang et al., J. Lightwave Technol. 32, 3631 (2014)
Y. P. Wang et al., Opt. Express 20, 19006 (2012)
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Au nanowireMode size diameter beam size possibly down to a single-molecule level
Optical confinement
In air
Y. P. Wang et al., Opt. Express 20, 19006 (2012)
Large momentum mismatchLow efficiency of photon-to-
plasmon conversion
High reflectivity at the nanowire endface
R. Kolesov et al., Nat. Phys. 5, 470 (2009)
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http://nano.imra.com/
Speed
Nano Lett. 9, 4515 (2009)
Nanosphere Nanorod Nanowire
Typical low-D metal nanostructures for nanoplasmonics
1. Introduction
0-D 1-D
Nano Lett. 12, 3145 (2012)
0-D Nanoparticle (e.g., nanorod: 20nmX100nm): Plasmon life time (LSPR) 10 fs @ 700 nm
Speed
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http://nano.imra.com/
Speed
Nano Lett. 9, 4515 (2009)
Nanosphere Nanorod Nanowire
Typical low-D metal nanostructures for nanoplasmonics
1. Introduction
0-D 1-D
Nano Lett. 12, 3145 (2012)
1-D Nanowire (e.g., 100-nm-diameter Ag Nanowire 0.4 dB/μm)
Plasmon life time (PSPP) 30 fs @ 700 nm
Speed
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http://nano.imra.com/
Speed
Nano Lett. 9, 4515 (2009)
Nanosphere Nanorod Nanowire
Typical low-D metal nanostructures for nanoplasmonics
1. Introduction
0-D 1-D
Nano Lett. 12, 3145 (2012)
Speed highly desired for ultrafast optical response
e.g, Ultrafast optical modulation
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http://nano.imra.com/
Speed
Nano Lett. 9, 4515 (2009)
Nanosphere Nanorod Nanowire
Typical low-D metal nanostructures for nanoplasmonics
1. Introduction
0-D 1-D
Nano Lett. 12, 3145 (2012)
Speed but high loss and broad resonance bandwidth
e.g, Ultracompact waveguide and plasmonic sensing
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Modal profiles of Au nanowires in water (a) 10 nm; (b) 20 nm @ 660 nm
Diameter (nm) Am (μm2) ƞ Lm (μm) α (dB/μm) 10 0.0001 29% 0.10 43.43 20 0.0004 30% 0.19 22.91 50 0.0023 38% 0.54 8.08
e.g., Au nanowire
Mode size 10 nm
Ultrahigh lossY. P. Wang et al., J. Lightwave Technol. 32, 3631 (2014)
Ultra tight confinement Ultrafast speed
Ultrahigh loss
Size and Speed
1. Introduction
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Ultra tight confinement Ultrafast speed
Broad resonance bandwidth
Size and Speed
1. Introduction
e.g., Au nanorod
P. Wang et al., Nano Lett. 12, 3145 (2012)
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Trade-off: “Confinement Loss Bandwidth” e.g., in subwavelength nanofiber/nanowire waveguides
X. Guo et al., Acc. Chem. Res. 47, 656 (2014)
Tight confinement High loss
Size and Speed
1. Introduction
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1. Introduction Nanoplasmonics in Metallic Nanostructures
Unique optical properties to enable routing and active manipulation of light at the nanoscale, and to bridge photonics and nanoelectronics.
M. L. Brongersma et al., Science 328, 440 (2010)
On the other side, dielectric and semiconductor nanostructures, with miniature size and low loss, may offer opportunities to nanoplasmonics…
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1. Introduction Nanoplasmonics in Metallic Nanostructures
Unique optical properties to enable routing and active manipulation of light at the nanoscale, and to bridge photonics and nanoelectronics.
M. L. Brongersma et al., Science 328, 440 (2010)
On the other side, dielectric and semiconductor nanostructures, with miniature size and low loss, may offer opportunities to nanoplasmonics…
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1. Introduction Nanoplasmonics in Metallic Nanostructures
Unique optical properties to enable routing and active manipulation of light at the nanoscale, and to bridge photonics and nanoelectronics.
On the other side, dielectric and semiconductor nanostructures, with miniature size and low loss, may offer opportunities to nanoplasmonics…
Nanofiber Coupled Nanoplasmonics
Optical micrograph of 650-nm light guiding through a silica (D=500 nm), a ZnO (D=300 nm) and a silver (D=100 nm) nanowires in cascade
X. Guo et al., Laser Photon. Rev. 7, 855 (2013)
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http://image.baidu.com
125 μm
Hair
500 nm
Optical fiber with diameter close to or below
L. M. Tong et al., Nature 426, 816 (2003)
Optical Nanofiber
Also appeared as “microfiber, nanowire etc. ”
1. Introduction
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Glass
Polymer
P. Wang et al., Light Sci. Appl. 2, e102 (2013)
Typical materials
L. M. Tong et al., Nature 426, 816 (2003)
1. Introduction Optical Nanofiber
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X. Q. Wu et al., Nanophotonics 2, 407 (2013)
Glass: Taper drawing
Nanofiber drawing system
Fabrication
1. Introduction Optical Nanofiber
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F. X. Gu et al., Nano Lett. 8, 2757 (2008)
Polymer: Solution drawing
Fabrication
1. Introduction Optical Nanofiber
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Uniform diameter
Smooth sidewall
Surface roughness (RMS) 0.2 nm
Circular cross-section
L. Tong et al., Opt. Express 14, 82 (2006)
Fabrication
1. Introduction Optical Nanofiber
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Elastic or plastic bending
L. Tong et al., Nano Lett. 5, 259 (2005)
Annealing-after-bending
Silica nanofibers
Silica nanofibers
Manipulation
1. Introduction Optical Nanofiber
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Tensile strength @RT
Silica NF > 5 GPaSpider silk 2 GPa
300-nm-diameter silica nanofiber with a elastic bending to a 4-μm radius
High mechanical strength
Manipulation
1. Introduction Optical Nanofiber
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Waveguiding Properties
1. Introduction Optical Nanofiber
.0)(
,0)(2222
2222
hkn
ekn
Helmholtz Equations
+Boundary conditions
Analytical solutions of guided modes [1]
[1] A. W. Snyder and J. D. Love, Optical waveguide theory, Chapman and Hall, New York, 1983.
Perfect cylindrical symmetry
rnrn
rn
,
0,)(
2
1
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Propagation constants (β)
Air-clad silica microfiber @ 633 nm
L. M. Tong et al., Opt. Express 12,1025 (2004)
Waveguiding Properties
1. Introduction Optical Nanofiber
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Air-clad silica microfiber @ 633 nm
X. Q. Wu et al., Nanophotonics 2, 407
(2013)
Waveguiding Properties
1. Introduction Optical Nanofiber
Evanescent fields & Energy distribution (HE11 modes)
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D (nm)400 800 1200 1600
0.0
0.2
0.4
0.6
0.8
1.0
633 nm
1550 nm
Silica/air
Fractional power inside the core
L. M. Tong et al., Opt. Express 12,1025 (2004)
Waveguiding Properties
1. Introduction Optical Nanofiber
Evanescent fields & Energy distribution (HE11 modes)
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D (nm)400 800 1200 1600
0.0
0.2
0.4
0.6
0.8
1.0
633 nm
1550 nm
Silica/air
D=200 nm
> 90% energy is guided in the air
Evanescent field
Near-field interactionFractional power inside the core
L. M. Tong et al., Opt. Express 12,1025 (2004)
Waveguiding Properties
1. Introduction Optical Nanofiber
Evanescent fields & Energy distribution (HE11 modes)
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Effective mode size
L. M. Tong et al., Opt. Express 12,1025 (2004)
λ =633 nm
Mode area for optical confinement of 86.5% in power
silica/air
Minimum effective mode size ~ 510 nm
Real diameter
Effective diameter
Possible to realize tightly confined large fractional
evanescent waves
Waveguiding Properties
1. Introduction Optical Nanofiber
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Nanofiber coupled
1. Introduction Nanofiber Coupled Nanoplasmonics
Nanowire plasmonicsPSPP
Nanorod plasmonicsLSPR
High efficiency photon-to-plasmon conversion
Plasmon lasers and sensors
Extraordinary strong coupling effects in coupled nanorod
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Outline
1. Introduction
2. Nanofiber coupled nanowire plasmonics
3. Nanofiber coupled nanorod plasmonics
4. Conclusion
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dielectric plasmonic
1-D nanofiber/nanowire for optical waveguiding
Bound electrons Free electrons
Maxwell Equations + Boundary conditions
Supporting waveguide modes
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Dispersion relation of SPP modes
The dashed line (ω=ck) denotes the dispersion line of light in free space.
To couple light into SPP modes in a nanowire
Momentum mismatch between the photons and plasmons must be compensated
PSPP excitation in a nanowire
X. Guo et al., Laser Photon. Rev. 7, 855 (2013)
2. Nanofiber Coupled Nanowire Plasmonics
Optical Launching
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Prism coupling
Lens-focus coupling
Bulk components with relatively low efficiency e.g.,<1%
PSPP excitation in a nanowire Optical Launching
Conventional approaches
X. Guo et al., Laser Photon. Rev. 7, 855 (2013)
2. Nanofiber Coupled Nanowire Plasmonics
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X. Guo et al., Laser Photon. Rev. 7, 855 (2013)
PSPP excitation in a nanowire Optical Launching Nanofiber coupling approach
photonic nanofiberplasmonic nanowire
Why it is possible?
2. Nanofiber Coupled Nanowire Plasmonics
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X. Guo et al., Nano Lett. 9, 4515 (2009).
PSPP excitation in a nanowire Optical Launching Nanofiber coupling approach
photonic nanowireplasmonic nanowire
the small end scatters evanescent waves for compensating momentum mismatch between the two waveguides
considerable overlap between the two modes
Why it is possible?
Light guided along a photonic nanowire leaves large fractional evanescent waves
2. Nanofiber Coupled Nanowire Plasmonics
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Photon-to-plasmon coupling efficiency ~80%
Silica nanofiber: D=500 nmAg nanowire: D=240 nm, L=12µm
X. Guo et al., Nano Lett. 9, 4515 (2009)
large overlap between the photonic and plasmonic modes
Endface scattering for compensating momentum mismatch
PSPP excitation in a nanowire Optical Launching Nanofiber coupling approach
2. Nanofiber Coupled Nanowire Plasmonics
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Photon-to-plasmon coupling efficiency ~92%
Silica nanofiber Ag Nanowire
X. Y. Li et al., Opt. Express 21, 15698 (2013)
Nanofiber: 300-nm diameterAg nanowire: 120-nm diameterWavelength: 785 nm
PSPP excitation in a nanowire Optical Launching Nanofiber coupling approach
2. Nanofiber Coupled Nanowire Plasmonics
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Coupling length ~220 nm
270-nm-diameter ZnO nanowire
240-nm-diameter Ag nanowire
X. Guo et al., Nano Lett. 9, 4515 (2009)
PSPP excitation in a nanowire Optical Launching Nanowire plasmonic branch couplers
2. Nanofiber Coupled Nanowire Plasmonics
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X. Guo et al., Nano Lett. 9, 4515 (2009)
PSPP excitation in a nanowire Optical Launching Nanowire plasmonic branch couplers
2. Nanofiber Coupled Nanowire Plasmonics
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Fractional output from the Ag nanowire: 488nm —— 4%
532nm —— 8%
650nm —— 64%
Coupling efficiency ~82%
Deducting the guiding loss:
Ag about 0.43 dB/µm
ZnO lower than 0.001dB/µm
X. Guo et al., Nano Lett. 9, 4515 (2009)
PSPP excitation in a nanowire Optical Launching Nanowire plasmonic branch couplers
2. Nanofiber Coupled Nanowire Plasmonics
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X. Guo et al., Nano Lett. 9, 4515 (2009)
PSPP excitation in a nanowire Optical Launching Nanowire plasmonic Mach-Zehnder Interferometer
2. Nanofiber Coupled Nanowire Plasmonics
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(1) Mach-Zehnder Interferometer
3-2. Hybrid “Photon-Plasmon” circuits and devices
As-assembled MZI
ZnO Nanowire: D 330 nm, L 89 µm
Ag Nanowire: D 120 nm, L 6.5 µm
X. Guo et al., Nano Lett. 9, 4515 (2009)
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ZnO Nanowire: D 330 nm, L89 µm
Ag Nanowire: D 120 nm, L 6.5 µm
FSR = 2.75 nm @710 nm
Potential applications: sensors, modulators etc.X. Guo et al., Nano Lett. 9, 4515 (2009)
PSPP excitation in a nanowire Optical Launching Nanowire plasmonic Mach-Zehnder Interferometer
2. Nanofiber Coupled Nanowire Plasmonics
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ZnO nanowire: 400-nm diameter
99.5-µm length
Ag nanowire: 265-nm diameter
16.5-µm length
X. Guo et al., Nano Lett. 9, 4515 (2009)
PSPP excitation in a nanowire Optical Launching Nanowire plasmonic ring resonator
2. Nanofiber Coupled Nanowire Plasmonics
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Reducing cavity loss without sacrificing confinement of the silver nanowire
Q = 520FSR = 3.8 nm
X. Guo et al., Nano Lett. 9, 4515 (2009)
PSPP excitation in a nanowire Optical Launching Nanowire plasmonic ring resonator
2. Nanofiber Coupled Nanowire Plasmonics
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Nanowire Plasmon Laser
X. Q. Wu et al., Nano Lett. 13, 5654 (2013)
Replacing the passive nanofiber with an active semiconductor nanowire
2. Nanofiber Coupled Nanowire Plasmonics
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X. Q. Wu et al., Nano Lett. 13, 5654 (2013)
Hybrid photon-plasmon nanowire laser
Nanowire Plasmon Laser
2. Nanofiber Coupled Nanowire Plasmonics
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2. Nanofiber Coupled Nanowire Plasmonics
Hybrid photon-plasmon nanowire laser
Nanowire Plasmon Laser
X. Q. Wu et al., Nano Lett. 13, 5654 (2013)
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2. Nanofiber Coupled Nanowire Plasmonics
X. Q. Wu et al., Nano Lett. 13, 5654 (2013)
(a, c) 390-nm-diameter CdSe NW 100-nm-diameter Ag NW
(b, d) The gain of the CdSe NW and the plasmonic resonance of the Ag NW are well matched in spectra.
(e) Assemble a hybrid cavity using the CdSe and Ag NWs.
(f) Coupling photoluminescene from the CdSe NW to the Ag nanowire.
Hybrid photon-plasmon nanowire laser
Nanowire Plasmon Laser
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(a) Lasing under a pump fluence of 97 μJ cm-2 (19.4 KW cm-2). (b) Lasing spectra collected from the Ag end-facet, under pump fluences of 27-97 μJ cm-2. (d) Emission intensity versus pump fluence collected from end-facets of the CdSe and the Ag NWs @ dominant lasing peak around 723 nm.
Photon-plasmon laser mode area of 0.008λ2
X. Q. Wu et al., Nano Lett. 13, 5654 (2013)
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X. Q. Wu et al., Nano Lett. 13, 5654 (2013)
Provides spatially separated plasmonic cavity modes with mode size down to deep-subwavelength scale
Ultrafast modulate/switch the laser by plasmonic response
Optical sensing, imaging, quantum information
Hybrid photon-plasmon nanowire laser
Nanowire Plasmon Laser
2. Nanofiber Coupled Nanowire Plasmonics
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Outline
1. Introduction
2. Nanofiber coupled nanowire plasmonics
3. Nanofiber coupled nanorod plasmonics
4. Conclusion
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Typical Au nanorods
3. Nanofiber Coupled Nanorod Plasmonics Plasmonic Nanorods
Size: 20 nm*100 nm; Lifetime: 10 fs Resonance wavelength: 700 nm; Resonance bandwidth: 50 nm
P. Wang et al., Nano Lett. 12, 3145 (2012) R. Ameling and H. Giessen, Laser Photon. Rev. 7, 141 (2013)
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Typical Au nanorods
3. Nanofiber Coupled Nanorod Plasmonics Plasmonic Nanorods
Scattering from individual nanorods is clearly seen, but the excitation efficiency is low due to the small absorption cross-section of single nanorod compared with the size of the excitation beam.
P. Wang et al., Nano Lett. 12, 3145 (2012)
Free-space excitation under an optical microscopy
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P. Wang et al., Nano Lett. 12, 3145 (2012)
3. Nanofiber Coupled Nanorod Plasmonics Optical launching single Au nanorods using nanofiber
Embed nanorods inside a polymer nanofiber
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Photon-to-LSPR-conversion efficiency for single nanorod70% @ 785 nm (coincided with the LSPR peak)
P. Wang et al., Nano Lett. 12, 3145 (2012)
Replacing the free-space excitation beam by tightly confined waveguiding mode of the nanofiber
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P. Wang et al., Nano Lett. 12, 3145 (2012)
Polymer nanofiber plasmonic sensors
3. Nanofiber Coupled Nanorod Plasmonics Nanofiber coupled Au nanorod sensor
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P. Wang et al., Nano Lett. 12, 3145 (2012)
500-nm-diameter nanofiber, 785-nm-wavelength probing light
Fast response ( 0.1 s) Very low operation power (0.5 nW) No photo-bleaching
Plasmonic nanorod humidity sensor
P. Wang et al., Nano Lett. 12, 3145 (2012)
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One possible approach coupling plasmonic nanorod to a photonic cavities similar to coupling an atom to a cavity
R. Ameling and H. Giessen, Laser Photon. Rev. 7, 141 (2013)
Resonance splitting
Anti- crossing
EIT …
Strong coupling Rabi splitting
3. Nanofiber Coupled Nanorod Plasmonics Plasmonic resonance band (life time) modification
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3. Nanofiber Coupled Nanorod Plasmonics Plasmonic resonance band (life time) modification
Resonance splitting
R. Ameling and H. Giessen, Nano Lett. 10, 4394 (2010)
One example: a pair of nanorods in a microcavity
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3. Nanofiber Coupled Nanorod Plasmonics Plasmonic resonance band (life time) modification
One example: a pair of nanorods in a microcavity
Fabry-Perot cavity (1 μm apart) formed by two parallel gold-mirrors
R. Ameling and H. Giessen, Nano Lett. 10, 4394 (2010)
Multi-band resonanceBandwidth > 5 nm
Resonance splitting
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Typically, the modified plasmonic resonance band shows
R. Ameling and H. Giessen, Laser Photon. Rev. 7, 141 (2013)
coupling plasmonic nanorod to a photonic cavities
Multiple resonance peaks mode splitting is not large enough to keep only one mode but shift out
all others out of the plasmonic resonance range
Obviously large background photon-to-plasmon conversion is not highly efficient in a single cycles of
the resonance
Relatively large bandwidth relatively large loss of the coupled system
P. Wang et al., Nano Lett. (In press)
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R. Ameling and H. Giessen, Laser Photon. Rev. 7, 141 (2013)
coupling plasmonic nanorod to a photonic cavities
Seeking a photonic microcavity with high Q, small size, and high photon-to-plasmon conversion efficiency
P. Wang et al., Nano Lett. (In press)
Typically, the modified plasmonic resonance band shows Multiple resonance peaks mode splitting is not large enough to keep only one mode but shift out
all others out of the plasmonic resonance range
Obviously large background photon-to-plasmon conversion is not highly efficient in a single cycles of
the resonance
Relatively large bandwidth relatively large loss of the coupled system
to single-band, narrow bandwidth, free background LSPR
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3. Nanofiber Coupled Nanorod Plasmonics Plasmonic resonance band modification
Again, microfiber or nanofiber becomes an excellent choice.
P. Wang et al., Nano Lett. (In press)
Tightly confined large fractional evanescent field 0.2-nm-level roughness Optical microcavity with high Q
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OMFC 1: using the fundamental (lowest-order) guiding mode
Optical Microfiber Cavity (OMFC)
X. Q. Wu et al., Nanophotonics 2, 407 (2013)
typical cavity length > 50 μm
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Bottle type
M. Sumetsky, Opt. Lett. 35, 2385 (2010)
Cylindrical microfiber
M. Pöllinger et al., Phy. Rev. Lett. 103, 053901 (2009)
possible to offer cavity length 5 μm
OMFC 2: using the whispering gallery (highest-order) mode
Optical Microfiber Cavity (OMFC)
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M. Sumetsky, Opt. Lett. 35, 2385 (2010)
Here, we choose cylindrical microfiber cavity
Easy fabrication No spatial requirement on nanorod
position Relatively high Q, despite of the
leakage “only 2.542 times less than that of a spheroidal microresonator”
Reasons
OMFC 2: using the whispering gallery (highest-order) mode
Optical Microfiber Cavity (OMFC)
Most importantly, cavity length < 5 μm : 10-fs single-cycle flying time of a photon comparable to life time of plasmon in a Au nanorod
Critical to obtain strong-coupling-induced large mode splitting P. Wang et al., Nano Lett. (In
press)
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Configuration & Structure
3. Coupled Microfiber-Nanoparticle System
Schematic: coupled microfiber-nanorod system
Coupled photonic WGMs of a microfiber and LSPR modes of a nanorod
P. Wang et al., Nano Lett. (In press)
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Configuration & Structure
3. Coupled Microfiber-Nanoparticle System
Fabrication: coupled microfiber-nanorod system
Silica microfiberAu nanorods P. Wang et al., Nano Lett. (In press)
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Configuration & Structure
3. Coupled Microfiber-Nanoparticle System
Characterization
Experimental setup
Broadband CW light
P. Wang et al., Nano Lett. (In press)
Page 75
Configuration & Structure
3. Coupled Microfiber-Nanoparticle System
Characterization
WGM mode excited by a single nanorod
Experimental setup P. Wang et al., Nano Lett. (In press)
Page 76
Weak Coupling
3. Coupled Microfiber-Nanoparticle System
large microfiber diameter (D>10 μm) Splitting/Linewidth <1
D=25.4 μm
P. Wang et al., Nano Lett. (In press)
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Weak Coupling
3. Coupled Microfiber-Nanoparticle System
large microfiber diameter (D>10 μm) Splitting/Linewidth <1
D=25.4 μm D=11.2 μm
Increase D Increase FSR P. Wang et al., Nano Lett. (In
press)
Page 78
Weak Coupling
3. Coupled Microfiber-Nanoparticle System
large microfiber diameter (D>10 μm) Splitting/Linewidth <1
Diameter-dependent FSR
Experimental data are in good agreement with the calculation
Experimental
Calculation
P. Wang et al., Nano Lett. (In press)
Page 79
3. Coupled Microfiber-Nanoparticle System Mode Splitting
When D is reduced below 10 μm single-cycle flying time <100 fs Mode splitting observed
e.g., D=5.6 μm
Splitting/Linewidth 1
P. Wang et al., Nano Lett. (In press)
Page 80
3. Coupled Microfiber-Nanoparticle System Strong Coupling smaller microfiber diameter (D<5 μm)
Splitting/Linewidth >1
Strong coupling occurs large mode splitting
P. Wang et al., Nano Lett. (In press)
Page 81
3. Coupled Microfiber-Nanoparticle System Strong Coupling smaller microfiber diameter (D<5 μm)
Splitting/Linewidth >1
D=1.46 μm
Strong coupling occurs large mode splitting
P. Wang et al., Nano Lett. (In press)
Page 82
3. Coupled Microfiber-Nanoparticle System Strong Coupling smaller microfiber diameter (D<5 μm)
Splitting/Linewidth >1
Splitting 42.9 nmLinewidth 2 nm
Splitting/Linewidth 20Splitting energy 133 meV
Strong coupling occurs large mode splitting
D=1.46 μm
The narrowest LSPR linewidth reported in a nanorod
Almost free background
Single-band
P. Wang et al., Nano Lett. (In press)
Page 83
3. Coupled Microfiber-Nanoparticle System Strong Coupling smaller microfiber diameter (D<5 μm)
Splitting/Linewidth >1
Strong-coupling induced 2-nm-linewidth single-band plasmonic resonance in a Au nanorod !
P. Wang et al., Nano Lett. (In press)
Page 84
3. Coupled Microfiber-Nanoparticle System Strong Coupling smaller microfiber diameter (D<5 μm)
Splitting/Linewidth >1
Strong-coupling induced 2-nm-linewidth single-band plasmonic resonance in a Au nanorod !
Shining 2-nm-linewidth light to launch LSPR in an uncoupled Au nanorod
What’s the difference?
650-nm laser light P. Wang et al., Nano Lett. (In
press)
Page 85
3. Coupled Microfiber-Nanoparticle System Strong Coupling smaller microfiber diameter (D<5 μm)
Splitting/Linewidth >1
Strong-coupling induced 2-nm-linewidth single-band plasmonic resonance in a Au nanorod !
Shining 2-nm-linewidth light to launch LSPR in an uncoupled Au nanorod
What’s the difference?
650-nm laser light
Dotted line: excitated under same spectral density
P. Wang et al., Nano Lett. (In press)
Page 86
3. Coupled Microfiber-Nanoparticle System Strong Coupling smaller microfiber diameter (D<5 μm)
Splitting/Linewidth >1
Agrees very well with calculation
Normalized electric field distribution
Nanorod
P. Wang et al., Nano Lett. (In press)
Page 87
3. Coupled Microfiber-Nanoparticle System Strong Coupling smaller microfiber diameter (D<5 μm)
Splitting/Linewidth >1
Agrees very well with calculation
Normalized electric field distribution
Nanorod
P. Wang et al., Nano Lett. (In press)
Page 88
3. Coupled Microfiber-Nanoparticle System Strong Coupling smaller microfiber diameter (D<5 μm)
Physical underlying Radiation to free space
Coherently pulled back into WGMs
D=1.46 μm P. Wang et al., Nano Lett. (In
press)
Page 89
3. Coupled Microfiber-Nanoparticle System Strong Coupling smaller microfiber diameter (D<5 μm)
Physical underlying
Significantly increased life time > 200 fs
650-nm laser light 10 fs
Better coherence
Radiation to free space
Coherently pulled back into WGMs
D=1.46 μm P. Wang et al., Nano Lett. (In
press)
Page 90
3. Coupled Microfiber-Nanoparticle System Strong Coupling smaller microfiber diameter (D<1 μm)
D=860 nm
Higher bending loss
P. Wang et al., Nano Lett. (In press)
Page 91
3. Coupled Microfiber-Nanoparticle System Strong Coupling smaller microfiber diameter (D<1 μm)
Higher bending loss
D=860 nm P. Wang et al., Nano Lett. (In
press)
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3. Coupled Microfiber-Nanoparticle System Strong Coupling smaller microfiber diameter (D<1 μm)
D=510 nm
No WGM availableBack to 50-nm
P. Wang et al., Nano Lett. (In press)
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3. Nanofiber Coupled Nanorod Plasmonics
Narrow-linewidth single-band plasmonic resonance
Plasmonic sensing & detection Better spectral resolution Higher sensitivity Lower detection limit
Potential applications
Deep-sub- plasmon laser Narrower linewidth Lower threshold Higher efficiency
Many others …
Route and manipulate light at the nanoscale with longer lifetime, better coherence, higher field enhancement and lower loss.
P. Wang et al., Nano Lett. (In press)
Page 94
Outline
1. Introduction
2. Nanofiber coupled nanowire plasmonics
3. Nanofiber coupled nanorod plasmonics
4. Conclusion
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Nanofiber coupled
4. Conclusion Nanofiber Coupled Nanoplasmonics
Nanowire plasmonicsPSPP
Nanorod plasmonicsLSPR
High efficiency photon-to-plasmon conversion
Plasmon lasers and sensors
Extraordinary strong coupling effects in coupled nanorod
Single-band 2-nm-linewidth LSPR
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X. Q. Wu et al., Nanophotonics 2, 407 (2013)
Outlook
96
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X. Q. Wu et al., Nanophotonics 2, 407 (2013)
Outlook
97
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Nanophotonics Group @ ZJU 2015 www.nanophotonics.zju.edu.cn
Current and former group members
Acknowledgement
Page 99
Collaborators
Acknowledgement
Prof. Qihuang Gong,
Yunfeng Xiao, Guowei Lu
Peking Univ, China
Prof. Eric Mazur Harvard University (USA)
Prof. Min QiuZhejiang University (China)
Prof. C. Z. NingASU (USA)
Prof. Jimin BaoUniversity of Houston (USA)
Prof. Younan XiaGatech (USA)
Page 100
National Science Foundation of China ( NSFC)
National Basic Research Program of China
Ministry of Education, China
etc.
Research Funds from
Acknowledgement