We report on a novel high-sensitivity method to characterize and improve mode matching into optical cavities. This method is based on heterodyne detection of cylindrical transverse cavity modes. A specially designed annular-segmented photodiode is used to measure the amplitude of nonresonant modes reflected by the cavity. Our measurements allow us to optimize cavity mode matching to nearly 99.98% and will play an important diagnostic role in gravitational-wave detectors.
© 2000 Optical Society of America
(040.2840) Detectors : Heterodyne
(120.0120) Instrumentation, measurement, and metrology : Instrumentation, measurement, and metrology
(120.2230) Instrumentation, measurement, and metrology : Fabry-Perot
(140.4780) Lasers and laser optics : Optical resonators
Guido Mueller, Qi-ze Shu, Rana Adhikari, D. B. Tanner, David Reitze, Daniel Sigg, Nergis Mavalvala, and Jordan Camp, "Determination and optimization of mode matching into optical cavities by heterodyne detection," Opt. Lett. 25, 266-268 (2000)