PHASE-SENSITIVE DETECTION OF LIGHT REFLECTED FROM A FABRY-PEROT-INTERFEROMETER

We present an analysis of the Fabry-Perot response to a phase-modulate d light in the reflection mode, by considering the general problem of the lock-in detection at the pth harmonics of the rf modulating freque ncy. Suitable frequency modulation conditions for servo-locking purpos es are obtained and the values of modulation index which maximize the sensitivity for the first, third, and fifth harmonics are found. Moreo ver, we investigate the effects of the residual amplitude modulation i ntroduced by the electro-optic frequency modulator, the presence of la ser amplitude and frequency noise, and the dependence of the achievabl e closed-loop frequency fluctuation spectrum on the modulation index a nd detection noise. (C) 1996 American Institute of Physics.