A Wide-Tuning Silicon Ring-Resonator Composed of Coupled Freestanding Waveguides

A wide-range wavelength-tunable silicon microring resonator is proposed using a microelectromechanical actuator. The microring consists of two U-shaped silicon freestanding waveguides and two directional couplers. The circumference of the microring is varied by the actuator. The wavelength dependence of the couplers is compensated by adjusting the coupling length while varying the circumference. The initial circumference of the microring is 19.1 μm and the free spectral range is 21 nm. The resonant wavelength of the microring is varied by 27 nm at the applied voltage of 25 V with negligible power consumption.