Intermittent spatial chaos in the polarization of counterpropagating beams in a birefringent optical fiber

Two counterpropagating intense light beams linearly polarized along the fast axis of a birefringent fiber may constitute a spatially unstable polarization eigenarrangement. Chaotic behavior in the steady-state polarization evolution of the waves occurs for input powers in a certain interval of values. By evaluating Lyapunov exponents we show intermittent trapping of irregular trajectories around regular islands. The characteristic length scale of this spatial disorder is typically of the order of one beat length.