Capacity considerations for multiplexed holographic optical data storage

The capacity of volume holographic data storage depends on the multiplexing efficiency of input holographic data arrays or pages. We compare this page-packing capacity of two common approaches: angle, and wavelength multiplexing. For maximal page packing the angular separation between the reference and signal beam incidence in the angle and wavelength multiplexing methods should be 90 degree(s) and 180 degree(s), respectively. We find that in these optimal arrangements both methods can multiplex a similar number of paraxial data-page signals, which is comparable to conceptual storage capacity limits derived from considerations of resolution in three-dimensions. In practice, the high number of multiplexed data pages predicted here will be compromised by material-related noise sources.