Robust self-trapping of vortex beams in a saturable optical medium

TL;DR

This paper demonstrates the first experimental observation of stable self-trapping of vortex beams in a saturable nonlinear medium, supported by numerical simulations, revealing stability limits at higher intensities.

Contribution

It provides the first experimental evidence of vortex beam self-trapping in a saturable medium and validates findings with numerical simulations including nonlinear effects.

Findings

Vortex beams with topological charge m=1 remain self-trapped over ~5 Rayleigh lengths.

Stability is maintained at moderate intensities but breaks at higher intensities.

Numerical simulations agree closely with experimental results.

Abstract

We report the first observation of robust self-trapping of vortex beams propagating in a uniform condensed medium featuring local saturable self-focusing nonlinearity. Optical vortices with topological charge m=1, that remain self-trapped over ~ 5 Rayleigh lengths, are excited in carbon disulfide using a helical light beam at 532 nm and intensities from 8 to 10 GW/cm^2. At larger intensities, the vortex beams lose their stability, spontaneously breaking into two fragments. Numerical simulations based on the nonlinear Schr\"odinger equation including the three-photon absorption and nonpolynomial saturation of the refractive nonlinearity demonstrate close agreement with the experimental findings.