Molecular-Field-Enhanced Optical Kerr Effect in Absorbing Liquids

A large enhancement of the optical Kerr nonlinearity associated with light-induced molecular orientation is observed in a liquid of anisotropic organic molecules when it is doped with a small amount of dye. The effect is ascribed to a photoinduced intermolecular force field, whose orienting action adds to the direct optical field action. The experimental results are in agreement with a model based on such interpretation. The proposed mechanism is in principle very general, and should work in all absorbing liquids made of anisotropic molecules.