New approach of beam fanning in BaTiO3 to improve a DPCM.

We propose here a new approach of a Double Phase Conjugate Mirror (DPCM) optimization in terms of stability and based on the study of the beam-fanning phenomenon for each interacting beam. This allows to chose the best angular configuration of both incident beams in DPCM. We took into account the influence of different parameters such as the power, the width and the angle of incidence of the laser beam for the two opposite entry faces perpendicular to the ferroelectric axis. In order to interpret the experimental data, we have developped a bidimensional model based on a Two Wave Mixing process, which is known to amplify the seed scattered by inhomogeneities of the crystal. The method is successfully used to determine the optimum DPCM configuration.