Small-sized optical gate switch using Ge2Sb2Te5 phase-change material integrated with silicon waveguide

An optical gate switch using Ge2Sb2Te5 phase-change material integrated with a silicon waveguide is reported. The switch is very small (similar to 2 mu m) owing to the large difference in absorption coefficient between the crystalline state and the amorphous state. The prototype switch has been fabricated and successfully switched from the transparent on-state to the opaque off-state by laser pulse irradiation. An extinction ratio of more than 12.5 dB was achieved over a wavelength range of 75 nm.