Polarization dispersion in randomly varying birefringence fiber

Abstract

Polarization dispersion of single-mode fibers with random birefringence is studied statistically. The extent of coupling between local polarization eigenmodes depends on the relative strength of the twist length and the beat length of the fiber. When the beat length is much shorter than the twist length, weak coupling theory applies.1 However, in regions where the fiber birefringence is nearly zero, the beat length is much longer than the twist length, so that the polarization eigenmodes are strangely coupled. In previous work, the region of zero birefringence has been modelled by a sudden random rotation of the fiber at regular interval. In this work, arbitrary random birefringence is considered. The correlation length of the electric fields is calculated in terms of that of the random variation of the fiber.