Feedback control of multiple mechanical modes in coupled micromechanical resonators

Abstract

Simultaneous control of multiple mechanical modes is demonstrated in AlGaAs/GaAs resonators by an optomechanical active feedback due to the photothermal stress. Four mechanical modes can be amplified with a single feedback loop, which is formed by a combination of an optical detector, an electrical delay line, and an optomechanical feedback source. The feedback polarities are tailored through the electric delay line, which enables individual control of the linewidths of each mechanical mode. Linewidth narrowing and damping control of multiple mechanical modes will be used for improving the detection sensitivity of mechanical sensor arrays and for controlling their ring-down speed.