We propose a novel type of unitary matrix for phase-code multiplexed holographic memories, which could be quickly generated from geometric sequences. Our analysis shows that the phase-code matrices are unitary rather than orthogonal. The new matrices have complex elements. The order of unitary matrices can be any positive integer, so that we can accommodate the available spatial light modulators to obtain the maximum possible storage capacity. The cross-talk noises in phase-encoded memories with unitary matrices and with Hadamard matrices are of the same order of magnitude, which are much lower than those in holographic memories with wavelength multiplexing or angle multiplexing.
© 2006 Optical Society of America
Original Manuscript: December 23, 2005
Manuscript Accepted: January 10, 2006
Xinzheng Zhang, Gernot Berger, Mathias Dietz, and Cornelia Denz, "Unitary matrices for phase-coded holographic memories," Opt. Lett. 31, 1047-1049 (2006)