Fiber-optic nonlinear coherent coupler

A new type of fiber-optic nonlinear coherent coupler consisting of a low-birefringence fiber and a fiber-optic polarization beam splitter is proposed. The principle of operation is based on nonlinear polarization change in the low-birefringence fiber. The characteristics of the fiber coupler are analyzed using the Stokes parameters formalism on the Poincaré sphere. The coupler is shown to be capable of acting as an intensity discriminator, pulse reshaper, and all-optical gate.