All-optical bistable band-edge Bloch modes in a two-dimensional photonic crystal

We demonstrate experimentally all-optical bistable operation in an InP-based two-dimensional photonic crystal slab lying on top of a Bragg reflector. Bistability is obtained around $1550\mathrm{nm}$ , using a low group velocity mode at the band edge of the photonic dispersion characteristic. The origin of the bistable regime is shown to be the fast ($275\mathrm{ps}$ relaxation time), electronically induced nonlinear refraction index. A low intensity threshold of $4\mathrm{kW}∕{\mathrm{cm}}^2$ was observed, with a contrast of 65% between the high and low reflectivity states.