Variable Grating Mode Liquid Crystal Device for Optical Processing Computing

Abstract

Certain nematic liquid crystal mixtures are observed to form a “variable grating mode” (VGM) for appropriate choices of cell design and applied voltage. In this mode of operation, a phase grating in the plane of the cell arises from a periodic variation in the orientation of the liquid crystal director. The grating spatial frequency is observed to vary linearly as a function of the applied voltage above the formation threshold. Liquid crystal and device parameters characteristic of the observed variable grating mode are presented. Utilization of the VGM effect in a photo-conductively-addressed device is shown to provide an intensity-to-spatial frequency conversion. Applications of this unique type of optical transducer to arbitrary nonlinear optical processing problems are described. Results of level slicing experiments and implementation of optical logic functions are presented.