Threshold of a Random Laser with Cold Atoms

Luis S. Froufe-Pérez (1) , William Guerin (2) , Rémi Carminati (3) , Robin Kaiser (2)

1 ICMM - Instituto de Ciencia de Materiales de Madrid
2 INLN - Institut Non Linéaire de Nice Sophia-Antipolis
3 Laboratoire Photons Et Matière

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.

Domaines: Physique Atomique [physics.atom-ph]; Systèmes désordonnés et réseaux de neurones [cond-mat.dis-nn]; Optique [physics.optics]

Luis S. Froufe-Pérez, William Guerin, Rémi Carminati, Robin Kaiser. Threshold of a Random Laser with Cold Atoms. Physical Review Letters, 2009, 102, pp.173903. ⟨hal-00343356v4⟩