摘要: This review presents a reflection-type holographic memory using three-dimensional(3D) speckle-shift multiplexing. First, the schematic of the proposed memory system was described. Then, experimental demonstrations of multiplexing in plane and along the depth direction were presented. The estimated storage capacity of single layer recording was introduced and the maximum storage capacity was discussed. To increase the storage capacity, the multi-layered recording was described. In the multi-layered recording, the storage capacity can be increased by appropriate arrangement of holograms in each layer.