Abstract:We experimentally investigate the slow light enhancement of nonlinear effects such as self-phase modulation, two-photon absorption and free carriers, through dispersion-engineered silicon photonic crystal waveguides. We also observe emission of visible light through thirdharmonic generation.

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We experimentally investigate four-wave mixing (FWM) in short (80 μm) dispersion-engineered slow light silicon photonic crystal waveguides. The pump, probe and idler signals all lie in a 14 nm wide low dispersion region with a near-constant group velocity of c/30. We measure an instantaneous conversion efficiency of up to -9dB between the idler and the continuous-wave probe, with 1W peak pump power and 6 nm pump-probe detuning. This conversion efficiency is found to be considerably higher (>10 × ) than that of a Si nanowire with a group velocity ten times larger. In addition, we estimate the FWM bandwidth to be at least that of the flat band slow light window. These results, supported by numerical simulations, emphasize the importance of engineering the dispersion of PhC waveguides to exploit the slow light enhancement of FWM efficiency, even for short device lengths.

We present a technique based on the selective liquid infiltration of photonic crystal (PhC) waveguides to produce very small dispersion slow light over a substantial bandwidth. We numerically demonstrate that this approach allows one to control the group velocity (from c/20 to c/110) from a single PhC waveguide design, simply by choosing the index of the liquid to infiltrate. In addition, we show that this method is tolerant to deviations in the PhC parameters such as the hole size, which relaxes the constraint on the PhC fabrication accuracy as compared to previous structural-based methods for slow light dispersion engineering.