Radiative losses due to pulse interactions in birefringent nonlinear optical fibers.

The transient evolution of two-polarization pulses in a birefringent nonlinear optical fiber, governed by coupled nonlinear Schrödinger (NLS) equations, is considered. The evolution is studied using a trial function consisting of coupled solitonlike pulses with varying parameters augmented by a radiative shelf in the Lagrangian formulation of the coupled equations, which yields ordinary differential equations for the pulse parameters. It is shown that including mass and momentum fluxes due to the radiative shelf is a requirement to obtain good agreement with full numerical solutions of the governing equations.