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“Nonlinear Real-Time Optical Signal Processing, Annual Technical Report”
by A.A. Sawchuk, T.C. Strand, and A.R. Tanguay
June 30, 1982
The results of a one year research program in nonlinear real-time optical signal processing are described. The goal of the program is to extend fast parallel nonlinear operations to optical processing systems with large time-bandwidth and space-bandwidth products. The research has concentrated on optical mode (VGM) liquid crystal real-time spatial light modulators. Parallel and twisted nematic liquid crystal light valve (LCLV) devices have been used as a nonlinear element in a feedback arrangement in the 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. 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. Preliminary theoretical modeling work to explain these effects is given, and an improved implementation of the intensity level slice function with VGM devices has been demonstrated. The project was a joint effort between the University of Southern California Image Processing Institute (USCIPI) and the Hughes Research Laboratories (HRL), Malibu, California.