Self-trapping and splitting of bright vector solitons under inhomogeneous defocusing nonlinearities

TL;DR

This paper demonstrates that in bimodal systems with spatially increasing defocusing nonlinearity, stable two-component solitons with separated components can form, including complex multipole structures, depending on the XPM interaction strength.

Contribution

It introduces the concept of stable vector solitons with separated components in inhomogeneous defocusing nonlinear media, highlighting the role of XPM interaction in their stability.

Findings

Stable two-component solitons with separated components are possible.

High XPM interaction leads to instability of overlapping solitons.

Complex multipole solitons can also be stable.

Abstract

We show that bimodal systems with a spatially nonuniform defocusing cubic nonlinearity, whose strength grows toward the periphery, can support stable two-component solitons. For a sufficiently strong XPM interaction, vector solitons with overlapping components become unstable, while stable families of solitons with spatially separated components emerge. Stable complexes with separated components may be composed not only of fundamental solitons, but of multipoles too.