Hamiltonian dynamics of solitons in optical fibers

A nonlinear optical fiber whose dispersion relation is weakly anisotropic in polarization can cause propagating pulses to undergo a self-induced rotation of polarization. The coupling of the cross-polarized optical fields is described by a pair of nonlinear Schrödinger equations and is studied as a Hamiltonian perturbation to an exactly integrable system with soliton solutions. Simplified descriptions involving low-dimensional dynamical systems for near-soliton evolutions are derived which explain the basic rotation of polarization and indicate a possible instability via interaction with the spatial pulse structure. The results of these dynamical approximations are compared with numerical computations for the full wave equations.