SPATIOANGULAR-MULTIPLEXING SCHEME FOR DENSE HOLOGRAPHIC STORAGE

A novel multiplexing scheme for dense holographic storage in photorefr active crystals, spatioangular multiplexing, is described in detail. C ompared with spatial multiplexing, spatioangular multiplexing increase s the storage capacity by fully utilizing the volume of the storage me dium. On the other hand, spatioangular multiplexing reduces the number of holograms overlapping any one hologram in a given volume and so in creases the diffraction efficiency achievable as compared with angular multiplexing. Using this scheme, we succeeded in storing 756 high-res olution patterns in an Fe:LiNbO3 crystal of volume 1 cm(3), with an av erage diffraction efficiency of 0.5%. This large database is designed for practical use in a novel associative-memory system, called a high- order feedback neural network.