Non-linear effects in NLC media undergoing two beams irradiation

A Nematic Liquid Crystal crossed by the overlap of multiple laser beams gives rise to different phenomena, such as the cancellation of reorientation and critical reorientation. A nonlinear 2D theoretical model is presented to describe these effects in the case of two laser beams impinging on a homeotropically aligned cell. By comparing the theoretical estimation of the re-orientational effect to the observed optical divergence of one beam, it is shown that they depend on the same phenomenon, although they are not directly correlated. Solutions given by the model show a good agreement with experimental results.