We present a signal extraction scheme for longitudinal sensing and control of an interferometric gravitational-wave detector based on a multiple-frequency heterodyne detection technique. Gravitational-wave detectors use multiple-mirror resonant optical systems where resonance conditions must be satisfied for multiple degrees of freedom that are optically coupled. The multiple-carrier longitudinal-sensing technique provides sensitive signals for all interferometric lengths to be controlled and successfully decouples them. The feasibility of the technique is demonstrated on a tabletop-scale power-recycled Michelson interferometer with Fabry–Perot arm cavities, and the experimentally measured values of the length-sensing signals are in good agreement with theoretical calculations.
© 1998 Optical Society of America
Daniel Sigg, Nergis Mavalvala, Joseph Giaime, Peter Fritschel, and David Shoemaker, "Signal Extraction in a Power-Recycled Michelson Interferometer with Fabry-Perot Arm Cavities by Use of a Multiple-Carrier Frontal Modulation Scheme," Appl. Opt. 37, 5687-5693 (1998)