Nonreciprocal frequency mixing in the nonlinear ΡΓ-symmetric hyperbolic metamaterials

The dispersion properties and combinatorial frequency generation by the PT-symmetric stack composed of hyperbolic metamaterial layers separated by dielectric media with balanced loss and gain have been investigated. It has been shown that the nonlinear response of the stack is strongly enhanced as the pumping wave frequency corresponds to the hyperbolic regime for nonlinear metamaterial layer. The effect of the pump wave nonreciprocal reflectance on the efficiency of the three-wave mixing process is illustrated by the simulation results. We have demonstrated that the rate of gain/loss in dielectric layers amplifies the intensity of the frequency mixing process.