Tunable Grating Coupler by Thermal Actuation and Thermo-Optic Effect

We demonstrate a tunable grating coupler on a Si-on-insulator platform through the use of both thermal actuation and thermo-optic effect. The grating coupler is designed to have beams that are fully etched and subsequently suspended to ensure that actuation is possible. By depositing aluminum oxide on alternate beams of the grating coupler, a directional actuation is ensured when the beams are heated. By combining both thermal actuation and thermo-optic effect, the central wavelength of the grating coupler can be tuned by 11.3 nm when the temperature difference is 30 K. Compared to tuning the grating coupler with just thermo-optic effect, the tunability of the grating coupler is increased by approximately 10 times.