Narrow band amplification of light carrying orbital angular momentum

Abstract

We report on the amplification of an optical vortex beam carrying orbital angular momentum via induced narrow Raman gain in an ensemble of cold cesium atoms. A 20\% single-pass Raman gain of a weak vortex signal field is observed with a spectral width of order of 1 MHz, much smaller than the natural width, demonstrating that the amplification process preserves the phase structure of the vortex beam. The gain is observed in the degenerated two-level system associated with the hyperfine transition $6S_{1/2}(F=3)\leftrightarrow 6P_{3/2}(F^{\prime }=2)$ of cesium. Our experimental observations are explained with a simple theoretical model based on a three-level $\Lambda$ system interacting coherently with the weak Laguerre-Gauss field and a strong coupling field, including an incoherent pumping rate between the two degenerate ground-states.

9 pages, 4 figures

References in corpus (5)

• Collapses and revivals of stored orbital angular momentum of light in a cold atomic ensemble
• A reversible optical memory for twisted photons
• Computation of topological charges of optical vortices via non-degenerate four-wave-mixing
• Off-axis retrieval of orbital angular momentum of light stored in cold atoms
• Topological stability of stored optical vortices

Cited by in corpus (2)

• High Helicity Vortex Conversion in a Rubidium Vapor
• Gaussian Beam-Propagation Theory for Nonlinear Optics - Featuring an Exact Treatment of Orbital Angular Momentum Transfer