Bragg gap solitons in $\mathcal{PT}$ symmetric lattices with competing nonlinearity

TL;DR

This paper investigates the existence and stability of Bragg gap solitons in $ ext{PT}$ symmetric optical lattices with competing nonlinearity, revealing their instability and comparing robustness of on-site versus off-site solitons.

Contribution

It demonstrates the existence of gap solitons in the first Bragg gap of $ ext{PT}$ symmetric lattices with competing nonlinearity and analyzes their stability properties.

Findings

Bragg gap solitons exist in $ ext{PT}$ symmetric lattices with competing nonlinearity.

These solitons are generally unstable during propagation.

Off-site gap solitons are more robust than on-site ones.

Abstract

The effect of competing nonlinearity on beam dynamics in parity-time $(\mathcal{PT})$ symmetric potentials is investigated. By using numerical methods, the existence of gap solitons is demonstrated in the first Bragg gap of optical $\mathcal{PT}$ symmetric lattices with competing nonlinearity. Meanwhile, the stability of such solitons is analyzed through introducing a small perturbation to the solitary solutions. The abrupt annihilation of the solitons during propagation demonstrates the Bragg gap solitons in $\mathcal{PT}$ symmetric potentials are not stable. In comparison with the on-site gap solitons, the off-site gap solitons exhibit more robust properties during propagation.