Steady-state nonlinear stimulated emission from a laser with a distributed feedback

A derivation is given of the equations describing steady-state stimulated emission from a laser with a distributed feedback which is ensured by interference, in the active medium, of two partly coherent optical pump beams. The threshold and output amplitude are calculated as a function of the pump rate and coherence, and the gain is found. It is shown that under certain conditions a laser of this kind can exhibit hard excitation conditions, which are of practical importance.