Low-Power Thermooptical Tuning of SOI

A wavelength selective optical switch is developed based on a high- racetrack resonator making use of the large thermooptic coefficient of silicon. The racetrack resonator was fabricated using a silicon-on-insulator (SOI) single-mode rib waveguide. The resonator shows a high factor of 38 000 with spectral sidelobes of 11 dB down and can be thermooptically scanned over its full free-spectral range applying only 57 mW of electrical power. A low power of 17 mW is enough to tune the de- vice from resonance to off-resonance state. The device functions as a wavelength selective optical switch with a 3-dB cutoff frequency of 210 kHz. Index Terms—Integrated optics, resonator, thermooptical switch, thermooptical tuning, silicon-on-insulator (SOI) tech- nology.