Current-driven phase-change optical gate switch using indium–tin-oxide heater

We proposed and fabricated a current-driven phase-change optical gate switch using a Ge 2 Sb 2 Te 5 (GST225) thin film, an indium–tin-oxide (ITO) heater, and a Si waveguide. Microfabrication technology compatible with CMOS fabrication was used for the fabrication of the Si waveguide. The repetitive phase changing of GST225 was obtained by injecting a current pulse into the ITO heater beneath the GST225 thin film. The switching operation was observed by injecting a 100-ns current pulse of 20 mA into the ITO heater. The average extinction ratio over the wavelength range of 1,525 to 1,625 nm was 1.2 dB.