In order to increase the optical communication bandwidth and improve the information processing rate, the research on high-speed code pattern conversion or high-speed phase switching has attracted much attention in recent years. This research direction is to study the new physical effects of photonic crystal microcavities and their microstructured waveguide systems, to study the new mechanism and key technologies of this type of all-optical switch, achieve chip integration, ultra-low pump optical power, picosecond-scale full-scale light switch.