Polarization effects in birefringent Bragg gratings with a Kerr nonlinearity

We show that a Kerr nonlinear, birefringent Bragg grating allows the investigation of three regimes of nonlinear pulse propagation. The regimes are entered by tuning the frequency of the pulse relative to the stop band of the grating. Detuning away from the stop band lowers the intensity required for solution formation, but increases the intensity required to observe polarization instability. We demonstrate numerically that it should be possible to observe a vector solitary wave in a long grating. We show experimentally that polarization instability is a strong function of the phase lag between the orthogonal polarizations.