Alignment-to-orientation conversion in a magnetic field at nonlinear excitation of the $D_2$ line of rubidium: experiment and theory

TL;DR

This study investigates how magnetic fields induce alignment-to-orientation conversion in rubidium's D2 line, combining detailed experimental measurements with a comprehensive theoretical model to understand the underlying atomic processes.

Contribution

It provides a combined experimental and theoretical analysis of alignment-to-orientation conversion in rubidium, accounting for hyperfine interactions, magnetic field effects, laser coherence, and Doppler broadening.

Findings

Observed signals depend on laser power density.

Identified structures in circular polarization components.

Theoretical model agrees with experimental data.

Abstract

We studied alignment-to-orientation conversion caused by excited-state level crossings in a nonzero magnetic field of both atomic rubidium isotopes. Experimental measurements were performed on the transitions of the $D_2$ line of rubidium. These measured signals were described by a theoretical model that takes into account all neighboring hyperfine transitions, the mixing of magnetic sublevels in an external magnetic field, the coherence properties of the exciting laser radiation, and the Doppler effect. In the experiments laser induced fluorescence (LIF) components were observed at linearly polarized excitation and their difference was taken afterwards. By observing the two oppositely circularly polarized components we were able to see structures not visible in the difference graphs, which yields deeper insight into the processes responsible for these signals. We studied how these signals are dependent on laser power density and how they are affected when the exciting laser is tuned to different hyperfine transitions. The comparison between experiment and theory was carried out fulfilling the nonlinear absorption conditions.