Locking the Advanced LIGO Interferometers

Jax Sanders, University of Michigan
Physics – Room 481

Abstract: The goal of the Advanced LIGO interferometric gravitational-wave detectors is to achieve the first direct detection of gravitational waves on Earth. The detectors are designed to measure strains as low at 4 x 10^-24/ root Hz. This sensitivity requires the use of optical cavities that must be kept on resonance with a locking system to predictably and robustly operate the interferometer at resonance. The arms are locked with the arm-length stabilization system, while the central Michelson interferometer is locked with a modulation technique using third harmonics. This method has resulted in the successful locking of the Advanced LIGO detector, which has been brought to an operating point where detecting gravitational waves is feasible.