The reduction of nonlinear response in near-surface layers by adjusting the electric field amplitude

Abstract

Abstract In this work, we use a special nonlinear dependence of dielectric permittivity to study theoretically the effect of a decrease in the nonlinear response in near-surface layers of a medium, which occurs with an increase in the amplitude of the electric field. We propose a model of nonlinearity in which the Kerr-type nonlinearity abruptly disappears with an increase in the field, and the dielectric permittivity becomes constant and independent of the field. Increasing the electric field leads to the formation of a local zone (optical domain) near the surface with linear optical properties where the dielectric permittivity becomes independent of the electric field. We formulate a nonlinear equation with stepwise dependence of the dielectric permittivity on electric field, and obtain its two types of exact solutions corresponding to the surface waves in media with positive (self-focusing) and negative (defocusing) nonlinear responses. We calculate and analyze the total power flows of thesurface waves of both types. We discuss in detail the features of the obtained solutions in comparison with previously published results. It is shown that the choice of a crystal with an appropriate nonlinear response makes it possible to increase or decrease the field intensity near the crystal surface with practically the same thickness of the near-surface layer with altered optical properties.