MULTIPLE NONLINEAR LIQUID CRYSTAL FILMS FOR OPTICAL WAVE MIXING.

The mechanism for optical beam amplifications and wave mixing in a Kerr-like medium is considered. In a thin nonlinear medium the authors have previously shown that it is possible to observe probe beam amplification even if the medium is a truly Kerr medium; i. e. , the nonlinear susceptibility is purely real. They describe theory and experiments on the extension of this effect to thicker samples, which are fabricated by stacking in tandem several independent nematic liquid-crystal thin films. This process eliminates the instabilities associated with thick films and enhances the nonlinearities of the individual film.