Radially symmetric and azimuthally modulated vortex solitons supported by localized gain

TL;DR

This paper demonstrates that localized gain can stabilize vortex solitons in nonlinear media, with gain profile topology limiting vortex charge and high gain inducing symmetry-breaking into necklace structures.

Contribution

It introduces a novel mechanism where localized gain stabilizes vortex solitons and reveals how gain topology influences vortex charge and symmetry breaking.

Findings

Localized gain stabilizes vortex solitons against azimuthal instabilities.

Gain profile topology restricts maximum vortex charge.

High gain levels cause symmetry breaking into necklace vortex solitons.

Abstract

We discover that a spatially localized gain supports stable vortex solitons in media with cubic nonlinearity and two-photon absorption. The interplay between nonlinear losses and gain in amplifying rings results in suppression of otherwise ubiquitous azimuthal modulation instabilities of radially symmetric vortex solitons. We uncover that the topology of the gain profile imposes restrictions on the maximal possible charge of vortex solitons. Symmetry breaking occurs at high gain levels resulting in the formation of necklace vortex solitons composed of asymmetric bright spots.