Photorefractive tungsten bronze materials for data storage applications

The photorefractive and electrical properties of ferroelectric tungsten bronze (T.B.) materials are reviewed with respect to optical data storage applications. Our work indicates that both the photorefractive properties (speed and coupling) and dark conductivity are sensitive to the type of T.B. host, dopants, and structural defects. The filled-lattice T.B. crystals exhibit faster response and lower dark conductivities, which are needed for data storage applications, as compared to unfilled T.B. crystals. Concepts for 3-D holographic memory applications using these materials arc discussed.