Abstract

Dense optical data storage can be achieved by angular and wavelength multiplexing of volume data holograms. In sequential hologram recording fewer holograms are multiplexed because of a reduction in the recording medium dynamic range. In simultaneous recording inter-modulation holograms are also recorded. In the present work, the reconstruction of up to 10 angular and wavelength multiplexed holograms is investigated by using the rigorous coupled-wave approach. Two types of interaction between the holograms are observed: direct cross talk and indirect cross coupling through a common reference or object beam. The effect of the angular/wavelength changes and individual grating diffraction efficiency on the direct cross talk and on the indirect cross coupling is determined. It is shown that for low diffraction efficiency holograms the principal diffraction may approach the design value by reducing the cross talk through increasing the angular/wavelength separation. For high diffraction efficiency gratings, indirect cross coupling is significant even for large angular/wavelength separation. This process limits the total number of multiplexed holograms and therefore limits the storage capacity. The issue of angular multiplexed versus wavelength multiplexed holograms is discussed. The effect of the data hologram bandwidth on the angular and wavelength multiplexing is presented.

© 1992 Optical Society of America