Mathematical Simulation of Random Coupling between Polarization Modes in Single-Mode Fiber Waveguides: I. Evolution of the Degree of Polarization of Nonmonochromatic Radiation Traveling in a Fiber Waveguide

摘要

The evolution of the degree of polarization of nonmonochromatic radiation traveling in single-mode fiber waveguides (SMWs) in the presence of random coupling between orthogonally polarized modes is analyzed. A model of random inhomogeneities in SMWs is proposed. The model takes into account a random twist of axes of natural linear birefringence of SMWs. The twist for the subsequent random section of a fiber is assumed to be independent of the twist for the preceding section, which corresponds to the Markovian random process. Using this model as the base, the dependence of the h parameter, which characterizes the coupling of polarization modes, on the magnitude of linear birebringence of SMWs is determined. The comparison of this dependence with the experimental results of various works shows that the model gives an adequate description of the problem. Using the Monte Carlo method, the dependence of the mean value and the mean-square deviation of the degree of polarization of nonmonochromatic radiation on the fiber length for SMWs with different birefringences is calculated. The theoretical dependences are compared with the results of experimental mea-surements of degree of polarization for nonmonochromatic adiation in SMWs. The theoretical results are found to be in good agreement with the experimental data.