Characterization of Quality-Factor Tunable Integrated Silicon

Microresonators are basic building blocks for compact photonic integrated circuits (PICs). The performance of the microresonators depends on their intrinsic and loaded quality factors (Q). Here we demonstrate the optical characterization of a single crystalline silicon microtoroidal resonator with integrated MEMS-actuated tunable optical coupler. The device is realized on a two-layer silicon-on-insulator (SOI) structure. It is fabricated by combining hydrogen annealing and wafer bonding processes. The device has been demonstrated to be operated in all three coupling regimes: under-coupling, critical coupling, and over-coupling. At an actuation voltage of 114 V, the extinction ratio at the resonant wavelength of 1548.18 nm reaches 22.4 dB. To characterize these quality-factor tunable microtoroidal resonators, we have also developed a comprehensive model based on time-domain coupling theory. The intrinsic and loaded Qs are extracted by fitting the experimental curves with the model. The intrinsic Q is 110,000. And the loaded Q is continuously tunable from 110,000 to 5,400. This device has potential applications in variable bandwidth filters, reconfigurable add-drop multiplexers, and optical sensors