Effect of random coupling of orthogonal modes on polarization characteristics of single-mode fiber optical waveguides (SMF) and SMF-based ring interferometers. I. Change in the degree of polarization of nonmonochromatic radiation propagating through a single-mode fiber optical waveguide

We propose a method for calculating the degree of polarization of nonmonochromatic radiation as it propagates through a single-mode fiber optical waveguide (SMF), based on dividing the length of the fiber into segments equal to the depolarization length of the radiation in the SMF. We have obtained the dependences of the degree of polarization of the radiation on the length of the fiber for an SMF with strong and weak anisotropy. In the case of anisotropic SMF's characterized by weak coupling of orthogonal modes, the results match those obtained previously by other calculation methods. The results for weakly anisotropic SMF's characterized by strong coupling of orthogonal modes are obtained here for the first time.