Enhancement of level-crossing resonances in rubidium atoms by frequency control of the exciting radiation field

TL;DR

This study investigates how controlling the frequency of laser radiation enhances magneto-optical resonances in rubidium atoms, with a detailed theoretical model matching experimental results across various conditions.

Contribution

It introduces a comprehensive theoretical model that accurately describes excited-state level crossings in rubidium, incorporating hyperfine interactions, magnetic sublevel mixing, laser coherence, and Doppler effects.

Findings

Resonance contrast is highly sensitive to laser frequency changes of tens of megahertz.

The theoretical model aligns well with experimental data across different laser power densities.

Frequency control can significantly enhance the visibility of level-crossing resonances.

Abstract

We studied magneto-optical resonances caused by excited-state level crossings in a nonzero magnetic field. 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. Good agreement between the experimental measurements and the theoretical model could be achieved over a wide range of laser power densities. We further showed that the contrasts of the level-crossing peaks can be sensitive to changes in the frequency of the exciting laser radiation as small as several tens of megahertz when the hyperfine splitting of the exciting state is larger than the Doppler broadening.