Quasi-compactons in inverted nonlinear photonic crystals

TL;DR

This paper investigates large-amplitude solitary waves in inverted nonlinear photonic crystals with saturable nonlinearity, revealing stable quasi-compactons, their mobility, and collision dynamics through numerical and analytical methods.

Contribution

It introduces the concept of quasi-compactons in INPhCs with saturable nonlinearity and analyzes their stability, mobility, and interactions, which were not previously studied.

Findings

Large-amplitude solitons are stable, broad, sharply localized pulses.

The centroid of QCs switches between potential minima and maxima with increasing power.

QCs are mobile in the saturable nonlinear medium, unlike in cubic INPhCs.

Abstract

We study large-amplitude one-dimensional solitary waves in photonic crystals featuring competition between linear and nonlinear lattices, with minima of the linear potential coinciding with maxima of the nonlinear pseudopotential, and vice versa (inverted nonlinear photonic crystals, INPhCs), in the case of the saturable self-focusing nonlinearity. Such crystals were recently fabricated using a mixture of SU-8 and Rhodamine-B optical materials. By means of numerical methods and analytical approximations, we find that large-amplitude solitons are broad sharply localized stable pulses (quasi-compactons, QCs). With the increase of the totalpower, P, the QC's centroid performs multiple switchings between minima and maxima of the linear potential. Unlike cubic INPhCs, the large-amplitude solitons are mobile in the medium with the saturable nonlinearity. The threshold value of the kick necessary to set the soliton in motion is found as a function of P. Collisions between moving QCs are considered too.