Fabry-Perot cavities with birefringent single-mode fibers and their applications as polarimetric sensors

The fields and resonance conditions of Fabry-Perot (FP) cavities containing several birefringent single-mode fibers are analyzed in terms of the fiber birefringence and misalignment of birefringent axes. For FP cavities with birefringent materials, two sets of fringes, corresponding to two cavity modes, are observed. Information is extracted from the separation between adjacent peaks of cavity modes of the same polarization as well as those of different polarizations. Thus an FP cavity containing birefringent fibers can be used as an optical-fiber polarimetric sensor without the use of polarization analyzers. Polarimetric sensors of this type are constructed and tested. The change of fiber birefringence due to a lateral stress applied to low-birefringence fibers is measured and the experimental results are shown to be in good agreement with the theoretical estimates