Polarization Characteristics of Single-Mode Fiber Couplers

The polarization characteristics of fiber couplers made of birefringent single-mode fibers are studied. The effect of anisotropic interfiber coupling, fiber birefringence, angular misalignment of fibers, and twisting on the coupler characteristics are identified. The polarization characteristics of the couplers are compared with that of isolated uncoupled fibers of the same birefringence and length. The equivalent lumped element representations for three classes of fiber couplers are also presented.