The insertion of a photorefractive crystal in a laser cavity leads to spectacular behaviours. The oscillating modes record a dynamic hologram. For a correctly designed cavity, this hologram acts as a spectral or/and spatial filter, which, in turn, modifies the relative losses of these modes. Through the interaction with the amplifying medium, this modification of losses redistributes the energy between the modes. This dynamic interaction is a self-adavptive process that can, after a short adaptation time, automatically force the laser to oscillate on a single transverse and longitudinal mode without any adjustment. We describe the main features of this adaptive process and its applications in various laser cavities.