Threshold of a Random Laser with Cold Atoms

TL;DR

This paper predicts the threshold and characteristics of a random laser using cold atoms, showing it is achievable with current experimental setups and can occur even with low scattering.

Contribution

It introduces a quantitative prediction of the lasing threshold and emission properties for cold-atom random lasers using two transport models.

Findings

Threshold b0 around 300 predicted

Random lasing possible at low scattering

Threshold within current experimental reach

Abstract

We address the problem of achieving an optical random laser with a cloud of cold atoms, in which gain and scattering are provided by the same atoms. The lasing threshold can be defined using the on-resonance optical thickness b0 as a single critical parameter. We predict the threshold quantitatively, as well as power and frequency of the emitted light, using two different light transport models and the atomic polarizability of a strongly-pumped two-level atom. We find a critical b0 on the order of 300, which is within reach of state-of-the-art cold-atom experiments. Interestingly, we find that random lasing can already occur in a regime of relatively low scattering.