Transfer of orbital angular momentum of light using two component slow light

TL;DR

This paper demonstrates a method to transfer orbital angular momentum from control laser beams to probe light in a cold atom medium, enabling vortex transfer in two-component slow light without switching off control beams.

Contribution

It introduces a double tripod atomic configuration that allows continuous vortex transfer between control and probe fields, improving upon single tripod schemes.

Findings

Successful transfer of optical vortex from control to probe fields.

Continuous vortex transfer without switching control beams.

Enhanced manipulation of slow light with orbital angular momentum.

Abstract

We study the manipulation of slow light with an orbital angular momentum propagating in a cloud of cold atoms. Atoms are affected by four copropagating control laser beams in a double tripod configuration of the atomic energy levels involved, allowing to minimize the losses at the vortex core of the control beams. In such a situation the atomic medium is transparent for a pair of copropagating probe fields, leading to the creation of two-component (spinor) slow light. We study the interaction between the probe fields when two control beams carry optical vortices of opposite helicity. As a result, a transfer of the optical vortex takes place from the control to the probe fields without switching off and on the control beams. This feature is missing in a single tripod scheme where the optical vortex can be transferred from the control to the probe field only during either the storage or retrieval of light.