High Helicity Vortex Conversion in a Rubidium Vapor

Abstract

The orbital angular momentum (OAM) of light is a quantity explored for communication and quantum technology, its key strength being a wide set of values offering a large basis for q-working. In this context we have studied the vortex conversion from a red optical vortex to a blue one, for OAMs ranging -30 to +30. The conversion is realized in a rubidium vapor, via the $5S_{1/2}-5D_{5/2}$ ${}^{85}Rb$ two-photon transition done with a Gaussian beam at 780 nm plus a Laguerre-Gaussian beam at 776 nm with the OAM $\ell$, producing a radiation at 420 nm. With co-propagating input beams, we demonstrate a conversion from red to blue for high-$\ell$ input vortices. We show that the output blue vortex respects the azimuthal phase matching, has a size determined by the product of the input beams and a power decreasing with $\ell$ in agreement with their overlap. Its propagation indicates that the generated blue wave is a nearly pure Laguerre-Gaussian mode. The vortex converter thus permits a correct OAM transmission.

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Cited by in corpus (11)

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• Interference effect and Autler-Townes splitting in coherent blue light generated by four-wave mixing
• Rapid readout of terahertz orbital angular momentum beams using atom-based imaging
• Spatial distribution of two symmetric four-wave mixing signals induced by Gaussian beams
• Dynamic Stark shift in a Doppler-broadened four-wave mixing
• Poincaré sphere symmetries in four-wave mixing with orbital angular momentum
• Spatial correlations in four-wave mixing with structured light
• Polychromatic forward-directed sub-Doppler emission from sodium vapour