Fast thermo-optic switch using direct current flow through waveguide in SOI

We investigate the response time of silicon-based thermo-optic switches under different device configurations. We design two tunable thermo-optic switches on a silicon-on-insulator (SOI) chip. One uses a waveguide embedded phase shifter based on direct heating due to electric current flow through waveguide. The other traditional switch structure has a metallic heater on top of the waveguide. Owing to direct current injection to heat the waveguide, which avoids the heat conduction from heater to waveguide, the switching time would reduce significantly. The experimental result shows that the direct heating device realizes a fast response time close to 1.5μs. As a comparison, the traditional heater-on-top device’s response time is over 10μs. That is to say, switching time of the direct-current-injection device is over ten times less. The insertion loss of both devices are reasonable. The fast heating device shows a potential for applications in the future optica interconnects.