Solitary modes in nonlocal media with inhomogeneous self-repulsive nonlinearity

TL;DR

This paper demonstrates the existence and stability of fundamental and dipole bright solitons in one-dimensional nonlocal media with inhomogeneous self-repulsive nonlinearity, highlighting the competition between spatial scales and multi-channel configurations.

Contribution

It introduces the first analysis of multi-channel soliton states in nonlocal media with inhomogeneous nonlinearity, including analytical solutions and stability conditions.

Findings

Stable multi-soliton states exist with sufficient spacing.

Analytical asymptotic solutions are derived.

Stable Josephson oscillations between channels are observed.

Abstract

We demonstrate the existence of two species of stable bright solitons, fundamental and dipole ones, in one-dimensional self-defocusing nonlocal media, with the local value of nonlinearity coefficient having one or several minima and growing at any rate faster than |x| at large values of coordinate x. The model can be derived for a slab optical waveguide with thermal nonlinearity. The most essential difference from the local counterpart of this system is the competition between two different spatial scales, the one determining the modulation pattern of the nonlinearity coefficient, and the correlation length of the nonlocality. The competition is explicitly exhibited by analytically obtained asymptotic form of generic solutions. Particular exact solutions are found analytically, and full soliton families are constructed in a numerical form. The multi-channel settings, with two or three local minima of the nonlinearity coefficient, are considered here for the first time, for both local and nonlocal models of the present type. States with multiple solitons launched into different channels are stable if the spacing between them exceeds a certain minimum value. A regime of stable Josephson oscillations of solitons between parallel channels is reported too.