Hughes Aircraft Company

Keyvan Sayyah

Chiung-Sheng Wu

A photoconductive substrate is provided to voltage modulate a liquid crystal layer in response to input light. The substrate is partitioned into electrically isolated pixels to eliminate lateral spread of charge carriers therein, and increase the dynamic range of the liquid crystal light valve while preserving resolution. The substrate is partitioned by forming an interconnecting network of deep trenches in a surface thereof, and filling the trenches with an insulating material such as silicon dioxide. The opposite surface of the substrate is etched away to expose the silicon dioxide in the trenches, thereby providing the substrate with partitions which extend completely therethrough between the opposite surfaces.

Method of fabricating an isolated pixel photoconductive structure

A light valve (10) includes a layer of a liquid crystal (16), a MOS substrate structure (18) with a dielectric layer (24) and a semiconductor layer (26), and an optically isolating mirror (14) between the liquid crystal layer (16) and the substrate structure (18). An external AC biasing voltage is applied across the MOS substrate (18) and the liquid crystal layer (16). The liquid crystal layer (16) is sufficiently thick that it operates in the surface birefringent mode with a high contrast ratio and a short response time to changes in the write-in light beam, when a sufficiently high biasing voltage V.sub.p is applied.

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Los Angeles, CA, United States of America

Keyvan Sayyah