PT-symmetric periodic structures with the modulation of the Kerr nonlinearity.

We study the PT-symmetric periodic layered structure with the modulated Kerr nonlinearity. We demonstrate that such systems can be transformed from the full to the broken PT symmetry or in the opposite direction. These transitions in the periodic structure with a finite length may be observed indirectly with the help of the dependence of the transmitted wave intensity on the incident wave intensity. Furthermore, the bistability properties depend on a gain and loss value and the choice of an input surface. The reduction of a feedback between counterpropagating waves is the main impact of the complex PT-symmetric refractive index variation on a bistability curve.