Cross-phase modulation induced modulation instability in negative index metamaterial with saturable nonlinear response

Abstract

The influence of nonlinear dispersion (originating from the dispersive permeability as well as from the nonlinear polarization) on cross-phase modulation (XPM) induced modulational instability (MI) in the negative index domain of metamaterials (MMs) with saturable nonlinearity is investigated numerically. The study explores various possible regimes of normal and anomalous group velocity dispersion and their combinations, which the two copropagating waves could experience in the negative refractive index domain of a MM. It has been shown that, under certain conditions, the first-order nonlinear dispersion, i.e., self-steepening (SS) and the second-order nonlinear dispersion (SOND), may lead to a considerable change in the MI gain spectrum. In addition, it is shown that, at higher perturbation frequencies, the SS effect causes considerable structural changes in the MI gain spectrum.