DRIFT INSTABILITY FOR A LASER-BEAM TRANSMITTED THROUGH A RUBIDIUM CELL WITH FEEDBACK MIRROR

We present the characteristics of the spatio-temporal instability that occurs when rubidium atoms interact with an incident laser beam and w ith the beam reflected from a tilted feedback mirror. We show that the re is a drift of the roll pattern that appears above threshold. Measur ements of the drift frequency are in excellent agreement with recent p redictions. An experiment done with two incident waves shows a more co mplex spatio-temporal behaviour.