PHASE-CONJUGATION IN CRITICAL MICROEMULSIONS

We present a model to describe degenerate four-wave mixing in critical binary liquid mixtures and we analyze it through an experimental stud y of phase conjugation in critical microemulsions. The two concentrati on gratings related to the four-wave-mixing configuration give contrib utions to the conjugated signal which can be separated from their diff erent formation and relaxation times. The model quantitatively describ es the amplitude and the dynamics of the gratings and thus of the conj ugate signal when one approaches the critical point. The theoretical p redictions fit very well with the experimental data. Close to the crit ical point a 10% reflectivity has been obtained in this medium using a beam power of 1 W from a cw Ar+ laser. The limitations of these refle ctivities at higher powers are discussed.