We describe and demonstrate a method to control a detuned movable-mirror Fabry-Pérot cavity using radiation pressure in the presence of a strong optical spring. At frequencies below the optical spring resonance, self-locking of the cavity is achieved intrinsically by the optomechanical (OM) interaction between the cavity field and the movable end mirror. The OM interaction results in a high rigidity and reduced susceptibility of the mirror to external forces. However, due to a finite delay time in the cavity, this enhanced rigidity is accompanied by an antidamping force, which destabilizes the cavity. The cavity is stabilized by applying external feedback in a frequency band around the optical spring resonance. The error signal is sensed in the amplitude quadrature of the transmitted beam with a photodetector. An amplitude modulator in the input path to the cavity modulates the light intensity to provide the stabilizing radiation pressure force.
Publication Source (Journal or Book title)
Physical Review A
Cripe, J., Aggarwal, N., Singh, R., Lanza, R., Libson, A., Yap, M., Cole, G., McClelland, D., Mavalvala, N., & Corbitt, T. (2018). Radiation-pressure-mediated control of an optomechanical cavity. Physical Review A, 97 (1) https://doi.org/10.1103/PhysRevA.97.013827