Observation of femto-joule optical bistability involving Fano resonances in high-Q/Vm silicon photonic crystal nanocavities

We observe experimentally optical bistability enhanced through Fano interferences in high-Q localized silicon photonic crystal resonances (Q ~ 30,000 and modal volume ~ 0.98 cubic wavelengths). This phenomenon is analyzed through nonlinear coupled-mode formalism, including the interplay of chi(3) effects such as two-photon absorption and related free-carrier dynamics, and optical Kerr as well as thermal effects and linear losses. Our experimental and theoretical results demonstrate for the first time Fano-resonance based bistable states with switching thresholds of 185 micro-Watt and 4.5 fJ internally stored cavity energy (~ 540 fJ consumed energy) in silicon for scalable optical buffering and logic

Observation of soliton pulse compression in photonic crystal waveguides

We demonstrate soliton-effect pulse compression in mm-long photonic crystal waveguides resulting from strong anomalous dispersion and self-phase modulation. Compression from 3ps to 580fs, at low pulse energies(~10pJ), is measured via autocorrelation

Ultracompact all-optical XOR logic gate in a slow-light silicon photonic crystal waveguide

We demonstrate an ultracompact, chip-based, all-optical exclusive-OR (XOR) logic gate via slow-light enhanced four-wave mixing (FWM) in a silicon photonic crystal waveguide (PhCWG). We achieve error-free operation (<10(-9)) for 40 Gbit/s differential phase-shift keying (DPSK) signals with a 2.8 dB power penalty. Slowing the light to v(g) = c/32 enables a FWM conversion efficiency, eta, of -30 dB for a 396 mu m device. The nonlinear FWM process is enhanced by 20 dB compared to a relatively fast mode of v(g) = c/5. The XOR operation requires approximate to 41 mW, corresponding to a switching energy of 1 pJ/bit. We compare the slow-light PhCWG device performance with experimentally demonstrated XOR DPSK logic gates in other platforms and discuss scaling the device operation to higher bit-rates. The ultracompact structure suggests the potential for device integration. (C) 2011 Optical Society of AmericaPublisher PDFPeer reviewe

Coupled-Mode Theory Analysis of Optical Bistability Involving Fano Resonances in High-Q/Vm Silicon Photonic Crystal Nanocavities

We study optical bistability associated with Fano resonances in high-Q/V[subscript m] silicon photonic crystal nanocavities through the nonlinear coupled-mode theory framework. The chi [superscript (3)] effects, free-carrier dynamics, thermal effects, and linear losses are included and investigated numerically. © 2007 Optical Society of America

Multi-photon absorption limits to heralded single photon sources

This work was supported in part by the Centre of Excellence (CUDOS, project number CE110001018), Laureate Fellowship (FL120100029) and Discovery Early Career Researcher Award (DE120102069, DE130101148, and DE120100226) programs of the Australian Research Council (ARC), EPSRC UK Silicon Photonics (Grant reference EP/F001428/1), EU FP7 GOSPEL project (grant no. 219299), and EU FP7 COPERNICUS (grant no. 249012).Single photons are of paramount importance to future quantum technologies, including quantum communication and computation. Nonlinear photonic devices using parametric processes offer a straightforward route to generating photons, however additional nonlinear processes may come into play and interfere with these sources. Here we analyse spontaneous four-wave mixing (SFWM) sources in the presence of multi-photon processes. We conduct experiments in silicon and gallium indium phosphide photonic crystal waveguides which display inherently different nonlinear absorption processes, namely two-photon (TPA) and three-photon absorption (ThPA), respectively. We develop a novel model capturing these diverse effects which is in excellent quantitative agreement with measurements of brightness, coincidence-to-accidental ratio (CAR) and second-order correlation function g((2))(0), showing that TPA imposes an intrinsic limit on heralded single photon sources. We build on these observations to devise a new metric, the quantum utility (QMU), enabling further optimisation of single photon sources.Publisher PDFPeer reviewe

Record 11 dB phase sensitive amplification in sub-millimeter silicon waveguides

We demonstrate phase sensitive amplification (PSA) in a 196µm silicon slow-light photonic crystal with an extinction ratio of 11dB. This record smallest phase sensitive amplifier is also the first demonstration of PSA in a photonic crystal