All-optical on-chip bit memory based on ultra high Q InGaAsP photonic crystal

We demonstrate all-optical bit memory operation with photonic crystal (PhC) nanocavities based on an InGaAsP substrate with a band gap at a wavelength of about 1.3 microm. The optical bistability is based on a refractive index modulation caused by carrier-plasma dispersion. The operating energy required for switching is only 30 fJ, and the minimum optical bias power for bistability is 40 microW, which is about one hundred times less than that required for laser based bistable memories.