Miniature Mid-Infrared Thermooptic Switch with Photonic Crystal Waveguide Based Silicon-on-Sapphire Mach-Zehnder Interferometers

Ultracompact thermooptically tuned photonic crystal waveguide (PCW) based Mach-Zehnder interferometers (MZIs) working in silicon-on-sapphire in mid-infrared regime have been proposed and demonstrated. We designed and fabricated a PCW based silicon thermo-optic (TO) switch operating at 3.43 mu m. Both steady-state and transient thermal analyses were performed to evaluate the thermal performance of the TO MZIs. The required pi phase shift between the two arms of the MZI has been successfully achieved within an 80 mu m interaction distance. The maximum modulation depth of 74% was demonstrated for switching power of 170 mW.