Electronically addressed spatial light modulator

Abstract

Coherent optical data processing is recognised to be a natural solution to certain information processing problems. Attempts to exploit the benefits of optical processing are limited by the quality of available Spatial Light Modulators. Spatial Light Modulators are devices which controllably impress information onto the amplitude or phase of an optical wavefront. They are used both to input data into an opticaI system and as modulating elements within the system (often in the Fourier plane of a Fourier transform processor).

This thesis describes the successful development of an electronically addressed spatial light modulator using liquid crystal as the light modulating material and a silicon integrated circuit as the addressing medium. It is a pixelated binary spatial light modulator operating in reflection. Each pixel contains a memory element which stores the programmed logical state of the pixel. The addressing and pixel circuits were fabricated in a 1.5m nMOS technology on a 10 mm square chip.

The pixels are arranged on a square array containing 50 x 50 elements. The liquid crystal was configured to modulate the light amplitude using the hybrid field effect in a nematic liquid crystal.

The spatial light modulator is used as a Fourier plane filter in a coherent optical processing system. Its performance is assessed and the direction of future research into this type of spatial light modulator is discussed.