Spontaneous symmetry breaking and vortices in a tri-core nonlinear fractional waveguide

TL;DR

This paper investigates a novel tri-core nonlinear fractional waveguide system, analyzing spontaneous symmetry breaking and vortex formation, with findings on stability, bifurcations, and mobility influenced by fractional dispersion and system parameters.

Contribution

It introduces a new model of coupled fractional waveguides and explores symmetry breaking and vortex stability, extending understanding of nonlinear fractional optical systems.

Findings

Identification of symmetric and asymmetric soliton states

Bifurcation diagrams showing regions of symmetry breaking

Analysis of vortex soliton mobility under fractional dispersion

Abstract

We introduce a waveguiding system composed of three linearly-coupled fractional waveguides, with a triangular (prismatic) transverse structure. It may be realized as a tri-core nonlinear optical fiber with fractional group-velocity dispersion (GVD), or, possibly, as a system of coupled Gross--Pitaevskii equations for a set of three tunnel-coupled cigar-shaped traps filled by a Bose-Einstein condensate of particles moving by L\'evy flights. The analysis is focused on the phenomenon of spontaneous symmetry breaking (SSB) between components of triple solitons, and the formation and stability of vortex modes. In the self-focusing regime, we identify symmetric and asymmetric soliton states, whose structure and stability are determined by the L\'evy index of the fractional GVD, the inter-core coupling strength, and the total energy, which determines the system's nonlinearity. Bifurcation diagrams (of the supercritical type) reveal regions where SSB occurs, identifying the respective symmetric and asymmetric ground-state soliton modes. In agreement with the general principle of the SSB theory, the solitons with broken inter-component symmetry prevail with the increase of the energy in the weakly-coupled system. Three-components vortex solitons (which do not feature SSB) are studied too. Because the fractional GVD breaks the system's Galilean invariance, we also address mobility of the vortex solitons, by applying a boost to them.