Polarisation dependent nonlinear interaction of two light beams in LiIO3 crystal

Abstract We measured the polarisation of the outgoing light beam of constant intensity induced by a nonlinear interaction with a second light beam of constant linear polarisation and variable intensity, in a thin plate of LiIO3 crystal. The change in the polarisation of the first beam depends on the direction of polarisation of the second beam and cannot be explained as a thermal phenomenon. We present a theoretical explanation of this effect based on the second-order optical nonlinearity of the LiIO3 crystal.