Steady-state signatures of radiation trapping by cold multilevel atoms

TL;DR

This study demonstrates radiation trapping in cold rubidium atoms through steady-state fluorescence measurements, supported by a simplified model linking optical thickness to fluorescence behavior.

Contribution

It provides the first experimental evidence of radiation trapping in cold multilevel atoms using steady-state measurements and a coupled rate equation-diffusive model.

Findings

Fluorescence intensity depends non-trivially on optical thickness.

Atomic populations and spectra align with radiation trapping predictions.

Model successfully explains experimental observations.

Abstract

In this paper, we use steady-state measurements to obtain evidence of radiation trapping in an optically thick a cloud of cold rubidium atoms. We investigate the fluorescence properties of our sample, pumped on opened transitions. The intensity of fluorescence exhibits a non trivial dependence on the optical thickness of the media. A simplified model, based on rate equations self-consistently coupled to a diffusive model of light transport, is used to explain the experimental observations in terms of incoherent radiation trapping on one spectral line. Measurements of atomic populations and fluorescence spectrum qualitatively agree with this interpretation.