Ultralow-power and integrated operation of all-optical switches/memories in a photonic crystal chip

The on-chip integration of all-optical switches and random-access memories based on a photonic crystal (PhC) nanocavity having a carrier-induced optical nonlinearity are presented. 25-channel all-optical gate switching and the wavelength-division multiplexing operation by silicon PhC nanocavity arrays were demonstrated with a femto-joule energy level. For the all-optical memory, an InP-based PhC nanocavity with an ultracompact buried heterostructure (BH) works well for strong confinement of photo-generated carriers, enabling an ultralow-power memory operation with nano-watt level. Integrated operation of all-optical memories was also demonstrated for the first time. Their ultralow power consumption, small footprint, and 40-Gb/s optical signal capability might be beneficial for future optical processing.