Polarization Coherence Theorem in Birefringent Nonlinear Single-Mode Optical Fibers

Eberly et al. [1] introduced the polarization coherence theorem (PCT): P-2 = V-2 + D-2, where the polarization P, visibility V, and distinguishability D are joined. In this work, we study the PCT in birefringent nonlinear single-mode optical fibers by considering circularly polarized input light fluctuating in amplitude. We analyze the behavior of the output PCT as a function of the linear birefringence and average input power. We demonstrate that the output light field undergoes a reduction of P and V but an increase of D when the linear birefringence approaches a critical value defined by the average input power; otherwise, P, V, and D remain unaffected. We also show how the average input power impacts P, V, and D by enhancing the linear birefringence.