Optomechanical Cooling and Inertial Sensing at Low Frequencies

An inertial sensor design is proposed in this paper to achieve high sensitivity and large dynamic range in the subhertz-frequency regime. High acceleration sensitivity is obtained by combining optical cav-ity readout systems with monolithically fabricated mechanical resonators. A high-sensitivity heterodyne interferometer simultaneously monitors the test mass with an extensive dynamic range for low-stiffness resonators. The bandwidth is tuned by optical feedback cooling to the test mass via radiation pressure inter-action using an intensity-modulated laser. The transfer gain of the feedback system is analyzed to optimize system parameters towards the minimum cooling temperature that can be achieved. To practically imple-ment the inertial sensor, we propose a dynamic cooling mechanism to improve cooling efficiency while operating at low optical power levels. The overall system layout presents an integrated design that is compact and lightweight.