Active, Switchable and Nonlinear Photonic Metamaterials

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1 Active, Switchable and Nonlinear Photonic Metamaterials Kevin F. MacDonald, and Nikolay, I. Zheludev Optoelectronics Research Centre & Centre for Photonic Metamaterials University of Southampton, UK Centre for Photonic Metamaterials

2 The 1 st Photonic Revolution Global Telecommunications Laser Medicine Optical Data Storage Laser Manufacturing

Disruptive Technologies of the 21 st Century - The next photonic revolution Nano US$ 1,000B by

6B by 2014 Photonics US$ 500B by 2021 Global market report by MarketsandMarkets there is much

These new materials, known as metamaterials or nanophotonic materials, are materials that can be

3 Disruptive Technologies of the 21 st Century - The next photonic revolution Nano US$ 1,000B by 2015 Nano- Photonics US$ 3.6B by 2014 Photonics US$ 500B by 2021 Global market report by MarketsandMarkets there is much promise in tailoring existing materials in novel ways to produce innovative results. These new materials, known as metamaterials or nanophotonic materials, are materials that can be developed to exhibit new optical properties that the original materials themselves would not naturally possess. National Research Council of the National Academies, USA (August 2012)

4 Metamaterials: mimicking nature, step 1 Metamaterial is a manmade media with all sorts of unusual functionalities that can be achieved by artificial structuring smaller than the length scale of the external stimulus. [N. I. Zheludev, Nature Materials 7, 420 (2008)] Atoms Plasmonic Resonators Natural Solid Electromagnetic Metamaterial

5 Metamaterials: mimicking nature, step 2 Plasmonic Resonators Active/nonlinear medium Superconducting quantum interference devices Electromagnetic Metamaterial Reconfigurable metamaterial Quantum Metamaterial

Centre for Photonic Metamaterials, University of Southampton Optoelectronics Research

Nikolay Zheudev (Director) Nanophotonics & Metamaterials Prof.

Dan Hewak Physics & Chemistry of Novel Glasses Prof.

Vassili Fedotov (EPSRC Career Acceleration Fellow) Metamaterials Electronics and Computer

Peter de Groot Superconductivity & Nano-magnetism Mathematics Prof.

6 Centre for Photonic Metamaterials, University of Southampton Optoelectronics Research Centre Prof. Nikolay Zheludev (ORC) Prof. Nikolay Zheudev (Director) Nanophotonics & Metamaterials Prof. Rob Eason Microstructured Materials 6.2M over 6 years Prof. Dan Hewak (ORC) Prof. Dan Hewak Physics & Chemistry of Novel Glasses Prof. Peter Ashburn (ECS) Physics and Astronomy Dr. Vassili Fedotov (EPSRC Career Acceleration Fellow) Metamaterials Electronics and Computer Science Prof. Janne Ruostekoski (Maths) Prof. Peter de Groot Superconductivity & Nano-magnetism Mathematics Prof. Janne Ruostekoski Quantum Optics Theory Prof. Peter Ashburn Nanofabrication & nano-devices Prof. Peter de Groot (Physics) Prof. Rob Eason (ORC) + ~25 research staff, PhD students & visitors Dr. Vassili Fedotov (ORC) Dr. Kevin MacDonald (ORC) Dr. Stewart Jenkins (Maths) Dr. Eric Plum (ORC) Dr. NikitasPapasimakis (ORC)

7 Metamaterial Tree of Knowledge 2010 Nonlinear MM Switchable MM Quantum MM Sensor MM Gain MM Metamaterials: artificial media with unique properties achieved by structuring on a scale smaller than the operational wavelength. Designer Dispersion MM Artificial Magnetism Transformation Optics & light localization Negative Index MM Chiral MM [Zheludev The Road Ahead for Metamaterials, Science, 328, 582 (2010)] Microwave Frequency Selective Surfaces

8 Metamaterial Tree of Knowledge Superconducting / quantum MM 2012 Nonlinear MM Organic MM Metadevices : devices with unique functions achieved by structuring on a scale smaller than the operational wavelength. Sensor MM MM light sources Light localization in MM Phasechange MM N/MEMS metamaterials Transf. Optics Artificial Magnetism Negative Index Chiral Designer Dispersion Microwave Frequency Selective Surfaces

9 Metamaterial light sources New tuneable and coherent nanoscale sources Electron beam Light emission Can we pump metamaterials light sources with free-electrons? Low-divergence, threshold-free, collective mode emission driven by electron beam Adamo, et al., Phys. Rev. Lett. 109, (2012) 50 nm Au ASR array 100 nm Si 3 N 4 Amplification of electron evanescent fields light collection electrons Electrons

10 Superconducting metadevices New platforms for THz and mm-wave modulation Quantum-level functionality: flux-exclusion metamaterials Sapphire EO sub-thz modulator YBCO film 200 μm Savinov, et al., Scientific Reports 2, 450 (2012) Control current Nb on sapphire

11 NEMS (Reconfigurable) metamaterials Dr. Eric Plum Session III (13:30 today) Low-dimensional carbon Optical forces Light localization Stereo & Toroidal Microscopic theory

12 Phase-Change and Nonlinear Metamaterials

13 Challenge: Nanoscale optical modulation ICT progression: Smaller, Faster, More efficient Control (Induces change Δn and/or Δκ) L ~tens of nm Signal Active medium N = n +iκ IBM concept: 3D processor with on-chip nanophotonics X Extended interaction lengths X Interferometers X Cavities

Absorption Solution: Photonic metamaterials ICT progression: Smaller, Faster, More efficient Control (Induces change Δn and/or Δκ) L ~tens of nm Photonic metamaterial Signal <λ Active medium N = n

14 Absorption Solution: Photonic metamaterials ICT progression: Smaller, Faster, More efficient Control (Induces change Δn and/or Δκ) L ~tens of nm Photonic metamaterial Signal <λ Active medium N = n +iκ IBM concept: 3D processor with on-chip nanophotonics Energy X Extended interaction lengths X Interferometers X Cavities Metamaterial hybridization Small Δn or Δκ Large change in resonant properties

15 Chalcogenide Phase-change Metamaterials: Non-volatile, reversible, all-optical switching B. Gholipour, J. Zhang, K. F. MacDonald, D. W. Hewak, and N. I. Zheludev Centre for Photonic Metamaterials

Chalcogenides: A material platform for future photonics Compounds of heavier Group 16 elements (S, Se, Te) Compositionally tuneable of properties amazingly flexible materials.

16 Chalcogenides: A material platform for future photonics Compounds of heavier Group 16 elements (S, Se, Te) Compositionally tuneable of properties amazingly flexible materials... perpetually underestimated in terms of their practical potential Yablonovitch (2004) Optical nonlinearity: ultrafast, low-power, all-optical signal processing, λ conversion IR transparency: out to 20 µm generation, guiding, modulation, detection of light Phase-change functionality Optically/electrically-induced amorphous <-> crystalline transitions. Fast, low-power, non-volatile switching. Optical discs P-RAM

Chalcogenide metamaterial modulator structure Chalcogenide

Capping layer GST Inert capping layer: 100 nm ZnS/SiO 2

Thickness < λ/150 Buffer layer Metamaterial 500 nm Plasmonic

17 Chalcogenide metamaterial modulator structure Chalcogenide phasechange layer: nm Ge:Sb:Te (GST) Thickness < λ/100 Capping layer GST Inert capping layer: 100 nm ZnS/SiO 2 Thickness < λ/15 Inert buffer layer: nm ZnS/SiO 2 Thickness < λ/150 Buffer layer Metamaterial 500 nm Plasmonic metamaterial: 50 nm Au on CaF/SiO 2 patterned by FIB / photolith. Thickness = λ/100 - λ/30

18 300 nm Large area, single-pulse, reversible optical phase switching Single 660 nm diode pulses uniform switching over 2000 μm 2 Amorphize 50 ns 0.25 mw/µm 2 Probe Crystallise 100 ns 0.1 mw/µm 2 Amorphous GST domain Amorphous Crystalline GST Metamaterial Metamaterial: 50 µm x 50 µm >15,000 ASR unit cells High Low transmission

19 A/C ratio Non-volatile, near/mid-ir, all-optical metamaterial modulators 400 nm metamaterial unit cell Device thickness 175 nm (~λ/9) 600 nm 220 nm (~λ/27) Contrast - NIR 4 Mid-IR 4 Trans. Ref. 2 Ref. Trans nm µm

20 Chalcogenide non-volatile, metamaterial switches Functional material platform with proven technological pedigree Robust switching performance beyond that of other phase-change media Metamaterial hybridization opens new exploitation horizons Nanoscale all-optical switching [4:1 contrast at λ/27 thickness] Memory meta-devices ; IR spatial light modulation Operational band adjustable across broad chalcogenide VIS-IR transparency range EO switching: Sámson, et al., Appl. Phys. Lett. 96, (2010) All-optical: Gholipour, et al., Adv. Mater. (in press) Centre for Photonic Metamaterials

21 Engineering Gold s Nonlinearity: Metamaterial framework as a functional medium M. Ren*, B. Jia, J. Y. Ou, E. Plum, J. Zhang, K. F. MacDonald, A. E. Nikolaenko, J. Xu*, M. Gu, and N. I. Zheludev * Nankai University, China Swinburne University of Technology, Australia Centre for Photonic Metamaterials

22 Gold nonlinearity sp-conduction band E F ΔE = 2.4 ev Virtual state ħω s ħω p xhlaseroptics.com Nonlinear? d-band Two Photon Absorption (2PA) Absorption between d- and sp-states via virtual intermediate state (lifetime < 1 fs) Ultrafast pump-probe response (photons must coincide in time) β ~10-8 m/w Metamaterial structuring enables enhancement and control over dispersion and sign of nonlinearity!

β (10-6 m/w) Gold nonlinearity enhancement Suppression Nonlinear absorption Nonlinear bleaching y 425 nm 8 7.

23 β (10-6 m/w) Gold nonlinearity enhancement Suppression Nonlinear absorption Nonlinear bleaching y 425 nm x 10-6 m/w [300x β Au ] x 6 50 nm Au on SiO 2 patterned by FIB Ti:Sapphire z-scan; 115 fs pulses; 6 µm focus 4 Flat gold β (x50) ~ Metamaterial β 2 Structuring 300x RESONANT ENHANCEMENT of gold s nonlinear absorption 0 Nonlinearity clear at ~3 mw avg. (peak I ~ few GW/cm 2 ) Ultrafast <100 fs response Wavelength, nm Ren, et al., Adv. Mater. 23, 5540 (2011)

Tuneability & application Cell size Absorption saturation fs modelocking 880 Experiment ~ β 930 nm 900 890 - Ultrafast optical limiting - fs all-optical switching System % T

24 Tuneability & application Cell size Absorption saturation fs modelocking 880 Experiment ~ β 930 nm Ultrafast optical limiting - fs all-optical switching System % T modulation Fluence, µj/cm 2 Response time, fs Gold metamaterial <100 Metamaterial + α-silicon >750 Metamaterial + CNTs <400 Plasmonic nanorods ~1000

25 Perfect Absorption and Transparency: Controlling light-with-light without nonlinearity J. Zhang, K. F. MacDonald, and N. I. Zheludev Centre for Photonic Metamaterials

26 Superposition principle light beams travelling in different and even opposite directions pass though one another without mutual disturbance. [Christian Huygens, Abhandlung über das Licht 1678 ] Action of light-on-light requires a nonlinear medium Nonlinear medium

27 Metamaterial perfect absorption and transparency Perfect transmission Strong Absorption Sub-wavelength thin film at NODE Sub-wavelength thin film at ANTI-NODE

28 Modulating light with NODE absorber zero thickness ANTI-NODE Heat [Single-beam A max = 50%] absorber Changing phase/intensity of one beam changes absorption (and so transmission) of the other

silica Single laser source provides coherent signal &

29 Modulating light-with-light without nonlinearity Metamaterial nano-absorber: 50 nm gold (~λ/13) on silica Single laser source provides coherent signal & control beams Control beam phase and/or intensity can be modulated

30 Modulating light-with-light without nonlinearity Total transparency Perfect absorption

31 Time-domain intensity modulation Control beam ON --> Total transparency for both Control beam OFF --> signal absorption khz demonstration; THz modulation possible

32 Light-by-light control without nonlinearity Perfect absorption AND transparency in a planar (<<λ) metamaterial 0 100% absorption controlled by phase/intensity Operational wavelength selected by design anywhere in VIS/NIR range THz modulation bandwidth Potential applications: All-optical modulation Pulse restoration Coherence filtering Zhang, et al. Nature - Light: Science & Applications 1, e18 (2012)

33 Photonic metamaterials: Nanoscale switching & modulation technologies 1. Chalcogenide hybrid metamaterials Proven material platform for electro/all-optical, non-volatile switching/memory devices Resonant contrast enhancement in sub-wavelength structures 2. Nonlinear nanostructured metal Resonant nonlinear absorption enhancement/suppression/inversion Femtosecond modelocking, optical limiting, switching 3. Perfect absorption and transparency Ultra-thin absorbers by design Light-by-light control at arbitrarily low intensity Centre for Photonic Metamaterials

34 Centre for Photonic Metamaterials

From Metamaterials to Metadevices

From Metamaterials to Metadevices Nikolay I. Zheludev Optoelectronics Research Centre & Centre for Photonic Metamaterials University of Southampton, UK www.nanophotonics.org.uk 13 September 2012, Southampton