Recent progress in photorefractive nonlinear wave mixing

We describe recent results which show the hyper-adaptive behavior of nonlinear photorefractive wave mixing: The first one is a passive transverse mode-locking effect. It is demonstrated for oscillations in a cavity formed by two phase conjugate mirrors which contains a saturable absorber. It gives a collapse of the cross section of the oscillating beam near the absorber. In a second experiment, a cavity extension of laser diode arrays is used for an active mode-locking and frequency tuning of the laser.