Supra optical nonlinearities (SON) of methyl red- and azobenzene liquid crystal-doped nematic liquid crystals

In nematic liquid crystal films doped with methyl-red dye or azobenzene liq uid crystal, we have observed extremely efficient optically induced directo r axis reorientation effects, and refractive index change coefficients > > 1 cm(2)/W. The basic mechanisms involved are determined to be optically ind uced space charge fields and flow reorientation, order parameter modificati on and molecular torques by the photo-excited dopant molecules. These supra -optical nonlinearities (SONs) enable nonlinear image conversion, optical l imiting and holographic grating formation with muW power lasers.