Nonlinear switching and pulse propagation in phase-shifted cubic quintic grating

We investigate numerically the nonlinear switching characteristics and pulse propagation behavior in the phase-shifted cubic quintic grating (CQG). The continuous-wave nonlinear switching curve shows an interesting feature whereby two switching thresholds and consequently double bistability hysteresis are formed in a certain detuning window. We show the unique bistability (U-bistability) region close to the upper-switching threshold in each of the hysteresis, where the high state in U-bistability can be reached when input is coming from low to high with fast rise time. For medium peak intensity Gaussian pulse propagation in phase-shifted CQG, the full-width at half-maximum of the output pulse varies in upward parabolic manner as the peak intensity increases, whereas for high peak intensity Gaussian pulse propagation, the output pulse will experience distortion from the Gaussian shape because of the compression in its leading edge and broadening in its trailing edge concurrently.