A mems controlled cavity optomechanical sensing system

Abstract

A novel high optical Q Si microdisk photonic cavity sensor is integrated to read out mechanical motion of an electrostatically actuated cantilever achieving 4.6 fm/Hz1/2 displacement sensitivity for sub-μW input power. The readout gain is electrically-tunable by a factor of 200. Using cold-damping feedback we reduce the thermal mechanical vibration by a factor of >1000, flattening the mechanical transfer function, and demonstrate broadband sensing with 100 kHz bandwidth, >2.5 times the fundamental mechanical frequency. With <20 m footprint and intrinsic readout bandwidth of >500 MHz, cavity optomechanics enables a practical and flexible MEMS sensing platform with a broad application range.