Thermooptically Tuned Photonic Crystal Waveguide Silicon-on-Insulator Mach–Zehnder Interferometers

Ultracompact thermooptically tuned photonic crystal waveguide (PCW) silicon-on-insulator Mach–Zehnder interferometers (MZIs) have been proposed and fabricated. A novel thermal design was employed to improve the device switching performance. Both steady-state and transient thermal analyses were performed to evaluate the thermal performance of the thermooptic MZIs. A switching time less than 20 $\mu$ s has been experimentally achieved, which clearly demonstrated the speed advantage using the new heating approach. The active length of the PCW-based MZIs was 80 $\mu$ m, nearly one order of magnitude shorter than the conventional silicon waveguide-based MZIs. A maximum modulation depth of 84% for a switching power of 78 mW was obtained at a wavelength of 1548 nm.