Degree of polarization in anisotropic single-mode optical fibers: Theory

The degree of polarization for propagation waves in anisotropic single-mode fibers is formulated in terms of light source spectrum, incident polarization condition, and fiber parameters. The polarization degree deterioration is based on the incident wave split into two eigenpolarization modes inherent in the fiber. Since the two eigenpolarization modes have different group velocities from each other, the degree of polarization is degraded when both of the modes are excited. Polarization degree is preserved when only one of the eigen-polarization modes is excited. The degradation is determined by the mutual correlation function γ, between the two modes, which depends on the light source spectra, fiber polarization dispersion, and fiber length.