Stabilization of one-dimensional Townes solitons by spin-orbit coupling in a dual-core system

TL;DR

This paper demonstrates that spin-orbit coupling-like effects can stabilize one-dimensional Townes solitons in a dual-core optical system with quintic self-focusing, expanding the understanding of soliton stabilization mechanisms.

Contribution

It introduces a novel stabilization method for 1D Townes solitons using SOC-like terms in a dual-core waveguide with quintic nonlinearity, supported by numerical and analytical analysis.

Findings

SOC-like terms stabilize 1D Townes solitons.

Skew-symmetric solitons are stable in certain bandgaps.

Moving solitons are unstable and evolve into breathers.

Abstract

It was recently demonstrated that two-dimensional Townes solitons (TSs) in two-component systems with cubic self-focusing, which are normally made unstable by the critical collapse, can be stabilized by linear spin-orbit coupling (SOC), in Bose-Einstein condensates and optics alike. We demonstrate that one-dimensional TSs, realized as optical spatial solitons in a planar dual-core waveguide with dominant quintic self-focusing, may be stabilized by SOC-like terms emulated by obliquity of the coupling between cores of the waveguide. Thus, SOC offers a universal mechanism for the stabilization of the TSs. A combination of systematic numerical considerations and analytical approximations identifies a vast stability area for skew-symmetric solitons in the system's main (semi-infinite) and annex (finite) bandgaps. Tilted ("moving") solitons are unstable, spontaneously evolving into robust breathers. For broad solitons, diffraction, represented by second derivatives in the system, may be neglected, leading to a simplified model with a finite bandgap. It is populated by skew-antisymmetric gap solitons, which are nearly stable close to the gap's bottom.