Supra optical nonlinearities of photosensitive nematic liquid crystals

A critical review of laser induced nonlinear index changing mechanisms in l iquid crystals is presented. In some azo-compound doped nematic films, we h ave observed nonlinear index coefficient much greater than 1 cm(2)/W. The s upra optical nonlinearities are attributed to photorefractivity, order para meter modification and dopant-nematic intermolecular torques, Using these n ematic films, we show that it is possible to perform image processing with muW/cm(2) optical intensity, and optical limiting with muW power lasers.