Three-dimensional confocal optical memory using photorefractive materials

Research on 3-D optical memory with photorefractive materials is described for ultra-high density/capacity memory exceeding the classical limit of conventional optical memory. In this system bit data are recorded by a focused laser beam as refractive digital bits in 3-D volume. A confocal laser-scan microscope is used for reading the recorded bit-data. In this paper, we show the system and the methods for writing and reading data, the materials we used, and some devices for practically realizing this type of memory. Some experimental examples obtained through the preliminary experiments are shown and the problems to be solved in future research and development are discussed.

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