Polariton spectrum in nonlinear dielectric medium

TL;DR

This paper theoretically analyzes the phonon-polariton spectrum in a nonlinear dielectric medium with Kerr-type nonlinearity, revealing how field intensity influences spectrum branches and leads to nonlinear wave phenomena.

Contribution

It introduces a theoretical model for the polariton spectrum considering third-order nonlinearity and explores the emergence of new spectrum branches due to dispersion effects.

Findings

New polariton spectrum branches appear in the gap at high intensities.

Dispersion of third-order susceptibility influences the spectrum structure.

Modulation instability leads to cnoidal waves and solitons.

Abstract

We obtain theoretically the phonon-polariton spectrum in nonlinear dielectric medium with the third order Kerr-type nonlinearity. We investigate the dependence of number of the polariton spectrum branches on the intensity of electromagnetic field and demonstrate that the appearance of new branches located in the polariton spectrum gap is caused by the influence of dispersion of the third order dielectric susceptibility at intensity field in the medium. The modulation instability of new branch waves leading to appearance of cnoidal waves and solitons.