Demonstration of 1000-times switching of phase-change optical gate with Si wire waveguides

1000-times stable switching operation of an optical gate incorporating a Ge₂Sb₂Te₅ thin film with Si wire waveguides is reported. The phase of the Ge₂Sb₂Te₅ was reversibly changed from the amorphous state to the crystalline state by the application of pulsed laser irradiation. The extinction ratio was 9.7 dB on average, and did not decline throughout the entire sequence of 1000 switching events induced by irradiation. The wavelengths of the signal light and of the laser pulses were 1550 nm and 660 nm, respectively.