Michelson interferometer thermo-optic switch on SOI with a 50-μW power consumption

We demonstrate photonic ultra-efficient thermo-optic switches on a 220-nm silicon-on-insulator platform. We used several approaches to increase the tuning efficiency of the switches. We used folded waveguides in a Michelson interferometer configuration to increase the optical interaction length of the light with the heated region, and used a suspended structure to improve thermal isolation. An ultra-low switching power of 50 μW is realized with an extinction ratio of over 26 dB for the transverse electric mode at 1550 nm. The 10%–90% response time of the switch is 1.28 ms, including a 780 μs rise time and a 500 μs fall time. Compared with the best thermo-optic switch in the literature, our device shows approximately an order of magnitude reduction in power consumption.