Novel speckle angular-shift multiplexing for high-density holographic storage

The volume holographic optical data storage has been an important and exciting area of research. Recently the more interested study for a high-density holographic memory is focused on the speckle wave used as a coded reference wave in various multiplexing techniques. In this paper, a novel speckle holographic storage scheme is proposed, which a random phase diffuser is added in the front of storage medium along the reference optical path of the original 90 degree storage geometry. In this scheme the incident angle of the reference beam and the place of the random phase diffuser illuminated by the reference beam can be changed simultaneously. The joint action of these changes generated a dynamic speckle wave for the reference beam in holographic storage. A theoretical model has been derived to describe the storage properties of this scheme based on the cross- correlation of dynamic speckle and the diffractive theory. The storage density influenced by the properties of the speckle patterns has been analyzed and experimentally confirmed. The results indicate that this scheme allows an increase in the data storage density with simple storage- retrieval architecture.