Reversible optical gate switching in Si wire waveguide integrated with Ge₂Sb₂Te₅ thin film

Reversible switching of an optical gate switch in a Si waveguide including a thin Ge₂Sb₂Te₅ phase-change material layer is reported. The phase-change was triggered by 660nm laser pulse irradiation onto the Ge₂Sb₂Te₅ layer with no structural damage. The switching time from the initial amorphous state to the crystalline state was 240ns, and that from the crystalline state to the amorphous state was 110ns. The maximum extinction ratios for switching-off and switching-on over the wavelength range from 1525 to 1600nm were 5.7 and 2.5dB, respectively.