Ultrafast nonlinear optical processing in photonics integrated circuits: Slow light enhanced Benjamin Eggleton ARC Laureate Fellow Director, CUDOS - Australian Centre of Excellence Centre for Ultrahigh-bandwidth Devices for Optical Systems Institute of Photonics and Optical Science (IPOS) School of Physics, University it of Sydney
Eggleton group Ultrafast coherent communications Quantum integrated photonics Nonlinear optical Phononics (SBS) Nonlinear optics Nanophotonics
Eggleton s research
Chip-based ultrafast nonlinear optics The photonic equivalent of an ultrafast integrated circuit: Femtosecond optical response Millimetre scale optical circuits To achieve these, we need: Ultrafast light-light interaction (10-12 s) Optical response Waveguides in novel nonlinear materials Photonic crystals (slow light enhanced NL)
Ultra-fast Kerr nonlinearity Nonlinear optics provides ultra-fast manipulation of light (e.g. switching,) P (1) (2) (3) 0 E EE EEE... n = n 0 + n 2 I (Intensity dependent refractive index) 2 n 2 A eff Self-phase modulation (SPM) Cross-phase modulation (XPM) Phase matched processes (Four-wave mixing) Third harmonic generation Raman Scattering Brillouin Scatttering
Planar waveguides As 2 S 3 Deposition of As 2 S 3 film Thermal evaporation Photolithography & dry etching n 2 ~110 silica Effective Area: ~1-5 µm 2 γ=2000 25,000 W -1 km -1 Prop. loss ~0.05-0.2db/cm Dispersion engineered Serpentine waveguide = 22 cm (~3dB loss)
Slow-light enhancement of NL effects Longer interaction time with material v g ~v phase v g <<v phase Effective nonlinearity ~ (slow-down factor) 2 Spatial pulse compression Enhanced interaction (path length) Ultra-compact operations and potentially energy efficient
Planar photonic crystal waveguides Planar photonic crystal: Slab (220nm)+2D PhC (air hole lattice a~400nm) Sub-µm optical confinement A ω ~0.4 µm 2 Light (k, ) Vlasov et al. Nature 2005 Even mode Coherent backscattering v g k Flat band 0 k [2 /a] 0.5 = Slow light Krauss J. Phys. D 2007
Slow light dispersion engineered waveguides Slow light versus resonator nonlinear enhancement Resonators: bandwidths from khz to at most a few GHz... 1µm v g ~c/40 10% 10nm (1.2 THz) band 26µm «Flat-band» Slow light 1µm Carmon et al. Nature Physics 2007 Narrow linewidth cw demonstrations Application to high bit rate all-optical signal processing Galli et al. Opt Express 18, 26613 (2010) Conversion efficiency ~2.10-8 (100 W in cw)
High bandwidth of the slow light PhC wgd 60 10 640Gb/s 33% RZ Corcoran et al. Opt Express 18, 7770 (2010) 50 0 (n g ) Gro oup Index 40 30 20 640Gb/s 33% RZ -10-20 -30-40 Po ower (dbm ) 10-50 0 3dB BW ~ 7.5nm 1545 1550 1555 1560 1565 1570 Wavelength (nm) -60
<100 micron optical switch
Enhanced third harmonic generation
Principle of OPM monitoring 40 Gbit/s to 640Gbit/s signal Slow Si Photodiode ħω T ħω T ħω ħω In-band ASE noise Constant Total Av. power ~ 100mW (input)/ ~10mW (coupled) Corcoran et al. Opt Express 18, 7770 (2010)
OSNR/dispersion Monitoring 160Gbit/s 14% 160Gbit/s 14% duty cycle THG induced green light: A clear function of the dispersion/osnr induced distortion of the signal 640Gbit/s 33% Corcoran et al. Opt Express 18, 7770 (2010)
PSA in Silicon PhC Waveguides propagating phase Gain PSA gain ω i ω p ω s 0 ϕ π PhC + TPA = PSA? Slow light enhances nonlinearity 10 TPA limits nonlinearity ph hase shift ( / / ) 5 No TPA TPA 0 Krauss J. Phys. D 40 2666 (2007) 0 5 10 Power (W)
PSA setup 30 nm TE Laser 40 MHz SPS EDFA SPS PC OSA Pump: 15ps, 1W(peak) Signal/idler:8ps, 10/20mW(peak)
In ntensity (db) -30-40 -50-60 -70-80 1552 1554 1556 1558 1560 (nm) PSA in Silicon PhC Waveguides (postdeadline OECC 2013) 0.7 0.5 0.2 4 2 0.2 +Gain 4 Gain (db) 0-2 -4-6 -8 10 db -Gain -10 0 02 0.2 04 0.4 06 0.6 08 0.8 1 / Gain: Gain (db) 2 0-2 -4 Max gain 11 db -6-8 Min gain -10 0 0.5 1 1.5 Peak Power (W)
Solitons compression in Bragg gratings and photonic crystals
Soliton compression in silicon photonic crystals N > 1 (compression regime) N 2 = L d / L NL L d =T 02 / 2 L NL =1 / ( eff P 0 ) -- Frequency-resolved gating --Increasing power EXPERIMENT (Time domain) Power coupled to PhC E o ~ 10 pj, c ~ 2 1.7 ps Key Points: -- Solitons possible in Si (i) (strong FC disturb ideal Kerr-GVD dynamics) (ii) Spectral blue shift due to free-carriers [1,2] (iii) Time domain acceleration [1] -- Picojoule pulse energies Challenging to measure these small pulse energie (< pj collected off-chip) --NLSE modelling underway Silicon Dr. Chad Husko (DECRA fellow) Andrea Blanco (Marie Curie Visiting Ph.D.) Dan Eades (Undergrad) 3.65 ps See also: [1] Husko et al., Scientific Reports 3, 1100 (2013) GaInP PhC solitons [2] Husko et al, CLEO US - QF1D.5 (Friday 9:15 AM) [3] Ding et al (Bath), Opt. Exp. 18, 26625 (2010) Si wire WG
Create world s first photonic platforms for practical, scalable quantum information operations for secure communications based on single photons Quantum integrated photonics photonics Quantum integrated t Quantum integrated photonics Tb/s coherent communications Free space optics Mid IR integrated photonics Zeilinger et al, Quantum teleportation experiment Photon pair generation by nonlinear mixing Hybrid integration Nanophotonics Integrated platform
Heralded single photon sources (3): Spontaneous four-wave mixing (SFWM) 2 Pump photons (3) medium Herald Detectors Input SFWM! Silica PCF Rarity, Opt. Express (2005). Silicon Waveguide Sharping, Opt. Express (2006). Silicon Rings Clemmen, Opt. Express (2009). Silicon Nanowire Harada, IEEE JSTQE (2010) Chalcogenide p Waveguide Xiong, i Opt. p Letters s (2010) i Silicon Photonic Crystal Xiong, Optics Letters (2011). Silicon CROW Davanço, APL (2012). Output p s Single Photon
Postdeadline CLEO 2011, Baltimore Postdeadline ECOC 2012 Amstedam Input ~centimeters Spatially compressed pump pulse Idler and signal = pairs of correlated photons Output p Fast light Slow light i p s Slow light Enhancement of the nonlinear FWM efficiency Ultra-compact sources (~100 m)
Eggleton s research
Fully integrated multiplexed single photon source SPDs C. Schuck, et. al., APL 102, p. 051101, 2013. RF CMOS electronic logic Pulsed pump laser input N Silicon PhCW s Integrated AWG s Heralded single photon outputnoise http://www.singlequantu port Low m.com/ loss D. Fiber Dai et. al., OpEx, Delay 9, no. 15, PLZT p. 14130, 2011. Nx2 switch
Multiplexing allows us to take probabilistic photon-pair sources and make a deterministic single photon source.
Further Integration Collins et al. Nature Communications, in-press. 63.1% enhancement 196µm g (2) (0) = 0.17 v g λ
Eggleton s research
Highly nonlinear chalcogenide glass Our work: As 2 S 3, As 2 Se 3, Ge 11 As 22 Se 67 High nonlinearity (ultra-fast ~ 50 fs response) n 2 ~ 100-1000 x silica Ultrafast pure Kerr effect (no free-carriers) Low two-photon absorption Compatible with Photonic integration Ultra-strong Raman/Brillouin scattering Mid-infrared transparent (2-10 m)
(TPA free) (Postdeadline paper, ECOC September 2012) 29
Heralded single-photon generation Coincidence to accidental ratio (CAR) Si PhCW CAR > 350 L = 196 µm ϒ ~ 4000 W -1 m -1 1. A. Clark et al, New J. Phys. 97, 211109 (2011) 2. C. Xiong et al, Appl. Phys. Lett. 98, 051101 (2011) 3. C. Xiong et al, Opt. Lett. 36, 3413 (2011)
Solution: Spatial multiplexing Spontaneous nonlinear process: nondeterministic Ultra-compact on-chip single-photon sources high photon number state On demand pump pulses (all from 1 laser) Nonlinear Sources Detectors Balance by multiplexing l i Fast feed-forward optical switch Sources that randomly generate photons Single mode On demand Single photons! Migdall Phys. Rev.A 66, 053805 (2002) PROPOSAL
Single photons enable Quantum communication Single photon Quantum key distribution Quantum teleportation Quantum computation Integrated Optics! Free space optics X. Jin, J. Ren, et al., Nature Photonics 4, 376-381 (2010) University of Bristol Politi, et al., Science 320, 646 (2008)