Polarizer-and analyzer-induced noise in fiber-optic polarization-sensitive intermodal interferometers

A theoretical and experimental study on the influence of imperfect polarizer/analyzer and their nonideal orientation along fiber axes on the generation of noise in bimodal polarization-sensitive interference is presented in this paper. It is shown that the polarimetric responses of each mode, the intermodal response of the orthogonal polarization as well as the crossed terms are superimposed upon the intermodal response considered to be the useful signal. The theoretical analysis is based on the use of spatial interferometric Stokes parameters and the Muller matrix method. Exact analytical expressions for the noise contributions are derived. Experimental data confirms the basic theoretical results and shows that the greatest noise contribution for a polarization-sensitive intermodal interferometer comes from the polarimetric and the crossed term.