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“Nonlinear Real-Time Optical Signal Processing, Annual Technical Report”
by A.A Sawchuk, T.C. Strand, and A.R. Tanguay
December 1983
The results of the second year of a two year research program in nonlinear real-time optical signal processing are described. The research has concentrated on optical sequential logic systems for parallel digital processing and on variable grating mode (VGM) liquid crystal real- time spatial light modulators. The goal of the program is to extend fast parallel nonlinear operations to optical processing systems with large time- bandwidth and space-bandwidth products. Parallel and twisted nematic liquid crystal light valve (LCLV) devices have been used as a nonlinear element in a feedback arrangement in the binary sequential logic system. A computer generated hologram fabricated on an e-beam system serves as a beam steering interconnection element. A completely optical oscillator and frequency divider have been experimentally demonstrated, and various circuit interconnection techniques have been explored. Research has continued on variable-grating mode (VGM) liquid crystal devices that perform local spatial frequency modulation as a function of the incident intensity. These devices can be used for nonlinear processing by selection and recombination of these spatial frequency components. These devices have many interesting physical effects with useful applications in both analog and numerical optical signal processing. Results on the physical modeling of VGM devices are given, with particular emphasis on experimental measurements of the Jones matrix describing polarized light propagation through the VGM cell.