An analysis of Kerr nonlinearity in negative index material and its effect on material characteristics

Abstract

Optics of negative index material is known for its unconventional results. In the perspective of nonlinear optics, it has a revolutionary impact. We, thus, investigate the effect of Kerr nonlinearity on the characteristics of a representative isotropic, frequency independent negative index material by defining an intensity-dependent effective permittivity and compare it to that in positive index material. Using the intensity-dependent permittivity, responses of essential characteristic features like phase and group velocities are studied and found to exhibit unconventional behavior with incident field intensity in the negative index material. At a threshold intensity, i.e., at an intensity at which effective permittivity vanishes, the material shows features of epsilon near zero and/or near zero index materials i.e., a diverging phase velocity with zero group velocity. The study shows the prospect of altering or tailoring characteristic features of a negative index material by tuning the field intensity of the propagating wave or pulse in the material.