Self-distributed feedback lasing in a system of cold atoms

We present a semiclassical analysis of lasing with an injected signal in a system of cold two-level atoms where the effects of atomic recoil are included self-consistently. This analysis predicts that the atoms may bunch under the effects of dipole forces to produce a density grating. This grating produces distributed feedback which can induce lasing action even when the gain of the atomic medium is less than the cavity losses.