Spatio-spectral vector light created by optical activity in rubidium vapor

TL;DR

This paper demonstrates a novel pump-probe technique using rubidium vapor to create spatio-spectral vector light, enabling spatially resolved polarization spectroscopy with potential applications in precision measurement.

Contribution

It introduces a new method combining optical activity in rubidium vapor with vector vortex beams to map frequency-dependent polarization effects onto spatial light structures.

Findings

Observed a 98 mrad per MHz image rotation on resonance.

Mapped optical activity onto spatial polarization structures.

Enabled spatially resolved polarization spectroscopy.

Abstract

We demonstrate a pump-probe scheme in which an atomic vapor is optically pumped with circularly polarized light and probed with a vector vortex beam. The pump induces a macroscopic magnetization in the medium, which gives rise to frequency-dependent circular dichroism and birefringence. The vortex probe, characterized by spatially varying polarization, maps this optical activity onto the spatial structure of the transmitted light, thereby generating correlations between the frequency, polarization, and spatial degrees of freedom. Measuring the intensity profile in a suitable polarization component then allows us to perform spatially resolved polarization spectroscopy. We demonstrate the translation of frequency shifts into an image rotation, observing on resonance a rotation in the order of 98 mrad per MHz. These findings may find applications in high-precision spectroscopy, magnetometry, and the generation of hybrid entanglement.