Raman process under condition of radiation trapping in a disordered   atomic medium
  We consider the Raman process developing in a disordered medium of alkali-metal atoms when the scattered modes are trapped on a closed transition. Our theoretical analysis, based on numerical simulations of the Bethe-Salpeter equation for the light correlation function, which includes all Zeeman states and light polarization, lets us track the stimulated amplification as well as the losses associated with the inverse anti-Stokes scattering channel. We discuss possible conditions when this process could approach the instability point and enter the regime of random lasing. 
L. V. Gerasimov, V. M. Ezhova, D. V. Kupriyanov, Q. Baudouin, W.   Guerin, R. Kaiser
physics.atom-ph quant-ph