Theory and Applications of Wave-Mixings in Photorefractive Crystals

Citation

Kwong, Sze-Keung (1986) Theory and Applications of Wave-Mixings in Photorefractive Crystals. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/atwv-t152. https://resolver.caltech.edu/CaltechTHESIS:10182019-170044100

Abstract

This thesis is an experimental and theoretical investigation of wave-mixing in photorefractive crystals and applications thereof. In the first part, the physics of the photorefractive effect is described. The figures of merit useful in characterizing various photorefractive crystals are also discussed.

In the second part, the coupled wave theory of two interacting optical waves in photorefractive crystals is reviewed. Both the energy coupling and the phase delay of the two beams are analyzed.

In the third part, the coupled wave formalism is extended to four wave mixing in photorefractive crystals. Aspects of real-time holography and phase conjugation are discussed. The coupled wave equations are solved in two special cases: (1) single grating and undepleted pump approximation; and (2) single grating and negligible absorption. The theory is then compared with the experimental results. The solutions of the phase of phase conjugation are presented. The recent developments in self-pumped phase conjugate mirrors are also discussed.

In the fourth part, new types of oscillators ultilizing the photorefractive gain are described and demonstrated. Two approaches to derive the conditions for unidirectional ring oscillation are presented and compared. The theory and experimental demonstration of a double phase conjugate resonator are described. Two applications, the optical path length to frequency conversion interferometer and the one-way real time wave front converters, are also described.

In the last part, some applications of the previous studies are described. Two novel bistable devices using the self-pumped phase conjugate mirror are demonstrated. Mathematical operations on images, such as real time 'exclusive or' operation, image subtraction, differentiation, and intensity inversion are demonstrated using an interferometer with a self-pumped phase conjugate mirror. Finally, the theory and the experimental demonstration of an all-optical associative holographic memory are discussed . Methods of extending the number of stored messages are also discussed.

Thesis Files