Date of Award

12-1990

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Department of Electrical and Computer Engineering

First Advisor

Steven K. Rogers, PhD

Abstract

The introduction of two-beam coupling in photorefractive materials has resulted in an extensive amount of research into their use as optical processing/computing elements. This dissertation develops the theoretical equations for two-beam coupling in barium titanate as an optical amplifier. One of the factors which limits the optical gain in photorefractive crystals is the loss of pump beam power to the amplification of parasitic light (beam fanning). This parasitic light is produced by light scattered from the pump beam by imperfections on both the crystal face and within the crystal. Through the analysis of signal and noise amplification as functions of pump and signal beam angles relative to the crystal c-axis, an optimum pump angle is defined which maximizes signal gain and minimizes the energy lost to beam fanning. The determination of an optimum gain is based upon a desired dynamic range and the crystal scattering characteristics. A potential application for the barium titanate optical amplifier is investigated in a system which produces negative feedback using destructive interference. Applications for such a system include image restoration, linear amplification, and image filtering.

AFIT Designator

AFIT-DS-ENG-90D-3

DTIC Accession Number

ADA230532

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