Abstract

In this review we discuss photorefractive effects associated with holographic storage in ferroelectrics from a materials, optical architecture and systems viewpoint. As a guide to the discussion a holographic storage system based on phase encoding for multiple superposition of interconnect patterns is presented. System performance is evaluated in terms of storage capacity, cross talk between superimposed patterns, S/N ratio, erasure upon readout, recording, erasure, and cycle times, and sensitivity. These performance characteristics are intimately related to materials properties and photorefractive processes in ferroelectrics. For example, cross talk between superimposed interconnect patterns is dependent, among other things, upon striations in the medium, the specifics of the multiplexing scheme, and the application of fixing procedures. Material inhomogeneities may be overcome by using phase conjugate readout techniques, and phase encoding allows many more holograms to be superimposed than is practical with angular encoding. Fixing may be achieved by recording at elevated temperatures, and the efficiency and duration of readout is affected by application of an electric field. These phenomena are re viewed in terms of the dependence of fundamental electro-optic properties on such parameters as applied field and temperature. Examples are given of experimental and modeling results.

© 1992 Optical Society of America