HOLOGRAPHIC STORAGE - THE QUEST FOR THE IDEAL MATERIAL CONTINUES

Throughout the 30-year history of holographic storage, an enormous number of material systems have been studied for use as the recording medium. In spite of the years and effort expended, the ideal material has not been identified and interest in holographic storage has waned. Recently, however, advances in both organic and inorganic photorefractive materials has rekindled interest in volume holography, not only for information storage but also as a technology that may be important for optical interconnects, neural networks and optical computing. Interest is further enhanced by continuing development in some of the enabling technologies, such as CCD arrays and spatial light modulators, necessary to make a viable storage product. After a brief introduction to holographic storage, this paper will concentrate on defining the systems requirements that drive material selection and review recent advances in photorefractive materials and techniques that address key issues. Included will be a discussion of multiplexing methods as well as various means to inhibit, or at least manage, destructive writing and reading. The paper will conclude with a discussion of the remaining critical issues as a focus for continued research and development.