The dynamics of direction-dependent switching in nonlinear chirped gratings

Nonlinear chirped gratings are numerically demonstrated to have a direction-dependent switching behavior. For the two incident directions, bistability exists with different switching-on powers, and the instable high transmissivity states have different critical powers. The direction-dependent bistability is due to the difference of the energy contained in the gratings for the two incident directions; the direction-dependent critical powers for instability origin from the different modulation instability threshold. Furthermore, it is first reported that for instable output there are spectral side lobes whose frequency shifts relative to carrier frequency have jumps at some input powers.