Nonlinear polarization changes in a birefringent fiber

The nonlinear evolution of the polarization state along a birefringent fiber has been numerically investigated using the Poincaré sphere representation. The polarization changes of intense light in a birefringent fiber are governed by a competition between intrinsic and intensity-induced birefringence. When the intrinsic birefringence is cancelled by the intensity-induced birefringence, the evolution of the polarization state along the fiber is sensitive to a small perturbation, i.e., a fluctuation of the birefringence. The trajectories of the polarization state exhibit a complex behavior.