Multicharged optical vortices induced in a dissipative atomic vapor system

TL;DR

This paper numerically studies the evolution of optical vortex beams in a dissipative atomic vapor under EIT conditions, revealing vortex formation, dynamics, and conservation of net topological charge, with implications for light behavior akin to liquids.

Contribution

It introduces a comprehensive numerical analysis of vortex dynamics in a dissipative atomic vapor considering multiple susceptibilities and EIT, providing new rules for vortex formation and evolution.

Findings

Vortices are induced in pairs with opposite charges during propagation.

The initial beam form and size significantly influence vortex dynamics.

Net topological charge remains conserved despite complex vortex interactions.

Abstract

We investigate numerically the dynamics of optical vortex beams carrying different topological charges, launched in a dissipative three level ladder type nonlinear atomic vapor. We impose the electromagnetically induced transparency (EIT) condition on the medium. Linear, cubic, and quintic susceptibilities, considered simultaneously with the dressing effect, are included in the analysis. Generally, the beams slowly expand during propagation and new vortices are induced, commonly appearing in oppositely charged pairs. We demonstrate that not only the form and the topological charge of the incident beam, but also its growing size in the medium greatly affect the formation and evolution of vortices. We formulate common rules for finding the number of induced vortices and the corresponding rotation directions, stemming from the initial conditions of various incident beams, as well as from the dynamical aspects of their propagation. The net topological charge of the vortex is conserved during propagation, as it should be, but the total number of charges is not necessarily same as the initial number, because of the complex nature of the system. When the EIT condition is lifted, an enhancement region of beam dynamics if reached, in which the dynamics and the expansion of the beam greatly accelerate. In the end, we discuss the liquid like behavior of light evolution in this dissipative system and propose a potential experimental scheme for observing such a behavior.