This volume is a collection of many of recent developments in area of photorefractive effects and materials. The photorefractive effect is now firmly established as one of the highest sensitivity, nonlinear optical effects, making it attractive for many optical holographic processing applications. As with all technologies based on advanced materials, the rate of progress in the development of photorefractive applications has been principally limited by the rate at which breakthroughs in materials science have supplied better materials. This book has been written to be accessible to materials scientists who are not experts in photorefractive materials, while at the same time providing the most up-to-date information for specialists. Students should find in it a clear introduction and reference, and it is also designed as a resource for researchers interested in learning about the most advanced discoveries of photorefractive effects, and applications of knowledge in the laboratory. References to over 400 original papers represent the personal selection of the contributing authors, identifying sources of additional information which will help guide the reader.