Phase-demodulation error of a fiber-optic Fabry-Perot sensor with complex reflection coefficients

The influence of reflector losses attracts little discussion in standard tr eatments of the Fabry-Perot interferometer yet may be an important factor c ontributing to errors in phase-stepped demodulation of fiber optic Fabry-Pe rot (FFP) sensors. We describe a general transfer function for FFP sensors with complex reflection coefficients and estimate systematic phase errors t hat arise when the asymmetry of the reflected fringe system is neglected, a s is common in the literature. The measured asymmetric response of higher-f inesse metal-dielectric FFP constructions corroborates a model that predict s systematic phase errors of 0.06 rad in three-step demodulation of a low-f inesse FFP sensor (R = 0.05) with internal reflector losses of 25%. (C) 200 0 Optical Society of America OCIS cocles: 060.2370, 120.2230.