FEEDBACK CONTROLLED OPTOMECHANICAL FORCE SENSOR

摘要

We present a new servo controllable force sensor that exploits photon momentum forces for the identification, calibration, and control of its dynamic properties. The sensor comprises a millimeter-scale glass cantilever, a low-noise fiber interferometer for detection of the cantilever deflection, and a high-power, intensity-modulated fiber laser to apply optical actuation forces. Combined with appropriate digital and analog signal processing, the sensor has been operated as a feedback-cooled low-noise force sensor, and as a self-excited oscillator governed by the familiar Rayleigh equation. Operated in this self-excited Quber mode, it appears well suited for noncontact, frequency modulated force gradient detection such as in atom discrimination. Here, we briefly lay out the principles of the sensor and provide examples of its performance, including the demonstration of feedback cooling and the ability to induce controlled limit cycle oscillations with atomic scale amplitudes.