Mixed-gap vector solitons in PT-symmetric lattices with saturable nonlinearity

TL;DR

This paper explores the formation and stability of mixed-gap vector solitons in PT-symmetric lattices with saturable nonlinearity, revealing how nonlinearity strength affects soliton properties and stability.

Contribution

It introduces the study of mixed-gap vector solitons in PT-symmetric lattices with saturable nonlinearity, highlighting the effects of nonlinearity strength on soliton existence and stability.

Findings

Vector solitons emerge from specific spectral gaps depending on nonlinearity type.

Stronger saturable nonlinearity narrows the existence domain of solitons.

Increased dipole component weight destabilizes solitons, while stronger nonlinearity can suppress instability.

Abstract

We have investigated mixed-gap vector solitons involving incoherently coupled fundamental and dipole components in a parity-time (PT) symmetric lattice with saturable nonlinearity. For the focusing case, vector solitons emerge from the semi-infinite and the first finite gaps, while for the defocusing case, vector solitons emerge from the first finite and the second finite gaps. For both cases, we find that stronger saturable nonlinearity is relative to sharper increase/decrease of soliton power with propagation constant and to narrower existence domain of vector solitons. This finding is helpful for realizing high-power solitons with limited range of propagation constant. Additionally, our numerical calculations show that increasing the weight of dipole component results in destabilization of vector solitons, while stronger saturable nonlinearity to certain extent suppresses the instability of vector solitons.