Optical vortices of slow light using tripod scheme

TL;DR

This paper explores the use of a tripod atomic scheme to propagate, store, and retrieve slow light with optical vortices, enabling vortex transfer and minimizing losses during the process.

Contribution

It introduces a novel tripod configuration allowing vortex transfer between control beams and the probe, enhancing slow light storage and retrieval capabilities.

Findings

Efficient transfer of optical vortex from control to probe beam.

Conditions identified for lossless vortex transfer.

Part of the probe remains as atomic spin excitations.

Abstract

We consider propagation, storing and retrieval of slow light (probe beam) in a resonant atomic medium illuminated by two control laser beams of larger intensity. The probe and two control beams act on atoms in a tripod configuration of the light-matter coupling. The first control beam is allowed to have an orbital angular momentum (OAM). Application of the second vortex-free control laser ensures the adiabatic (lossles) propagation of the probe beam at the vortex core where the intensity of the first control laser goes to zero. Storing and release of the probe beam is accomplished by switching off and on the control laser beams leading to the transfer of the optical vortex from the first control beam to the regenerated probe field. A part of the stored probe beam remains frozen in the medium in the form of atomic spin excitations, the number of which increases with increasing the intensity of the second control laser. We analyse such losses in the regenerated probe beam and provide conditions for the optical vortex of the control beam to be transferred efficiently to the restored probe beam.