<title>Holographic storage using phase-code and rotation multiplexing</title>

Abstract

Multiple holograms can be storage in a volume holographic medium such as photorefractive crystal or photopolymers by using phase-code multiplexing. However, due to the limited performance of currently available spatial phase encoders, only a small number of orthogonal phase codes can be implemented. This significantly limits the capacity of holographic systems based on phase-code multiplexing scheme. In this paper, a new multiplexing method, rotation multiplexing, is presented. After a number of holograms are stored by phase-code multiplexing, the holographic medium is rotated in the incident plane by a small angle. New holograms can then be stored by the same phase-codes without cross talk. By combining the phase-code and rotation multiplexing schemes, a high capacity 3D storage system can be built with off-the-shelf devices. An additional advantage of such a holographic storage system is its burst retrieval mode that is useful for network applications. The preliminary experimental results demonstrate the feasibility of the proposed approach.