Silicon microtoroidal resonators with integrated MEMS tunable coupler

A single crystalline silicon microtoroidal resonator with integrated MEMS-actuated tunable optical coupler is demonstrated for the first time. It is fabricated by combining hydrogen annealing and wafer bonding processes. The device operates in all three coupling regimes: under-, critical, and over-coupling. We have also developed a comprehensive model based on time-domain coupling theory. The experimental and theoretical results agree very well. The quality factor (Q) is extracted by fitting the experimental curve with the model. The unloaded Q is as high as 110 000, and the loaded Q is continuously tunable from 110 000 to 5400. The extinction ratio of the transmittance is 22.4 dB. This device can be used as a building block of resonator-based reconfigurable photonic integrated circuits.