Optomechanical instabilities in laser interferometer gravitational wave detectors

A laser interferometer gravitational wave detector stores about megawatts of optical power inside the cavities to improve the detector sensitivity. The strong coupling between the high intensity light field and the cavity mirror motions gives rise to optomechanical instabilities. This thesis investigates systematically these instabilities: the angular instability caused by the interaction between radiation pressure and the mirror angular control system, and the parametric instability due to the interaction between the cavity optical modes and the mirror internal modes fuelled by high optical power. All the works were carried out in Gingin High Optical Power Test Facility.