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

We investigate the response times of two silicon-based thermo-optic switches with the different heating methods on a silicon-on-insulator (SOI) chip. We design two tunable thermo-optic switches. 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 less than 1.5 mu s. As a comparison, the traditional heater-on-top device's response time can exceed 15 mu s. The insertion loss of both devices is reasonable. The fast direct heating device shows a promising potential for applications in the future optical interconnects.