NONLINEAR-OPTICAL SWITCHING IN BIREFRINGENT GRATINGS

We consider polarization mixing in birefringent fibers with imposed bi refringent gratings. For polarizations near the fast axis, the grating suppresses the well-known strong instability and mode mixing until a threshold power is reached, and then there is a sharp transition from linear to enhanced nonlinear behavior. The exact degree of grating bir efringence is not critical.