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Proceedings Paper

Improved multiplexing density in volume holographic memories through beam apodization
Author(s): Brian M. King; Mark Allen Neifeld; Xuewen Chen
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Paper Abstract

Volume holographic memories (VHM) achieve large storage capacities by multiplexing many holographic data pages in a small volume. On retrieval, a reference beam addresses the optical memory reconstructing the desired hologram with a large diffraction efficiency. In addition, all the other multiplexed holograms also reconstruct at a very low diffraction efficiency as determined by the Bragg selectivity function (BSF) of the VHM. To achieve low crosstalk the multiplexing scheme stores pages on the periodic nulls of the BSF. Absorption in the crystal corrupts the nulls requiring an increased multiplexing spacing between pages. Analysis of grating formation in photorefractive crystals relates the BSF to the transverse spatial electric field of the reference beam. This permits apodization of the reference beam as a method to shape the Bragg selectivity function and hence control the crosstalk noise. Furthermore, apodization can be incorporated into the VHM system metric, M/#, by considering the adjusted recording slope and reconstruction illumination. Theoretical predictions show that apodization can strongly attenuate the crosstalk noise allowing high multiplexing density in exchange for a small loss in the system M/#.

Paper Details

Date Published: 24 May 2000
PDF: 6 pages
Proc. SPIE 4089, Optics in Computing 2000, (24 May 2000); doi: 10.1117/12.386816
Show Author Affiliations
Brian M. King, Optical Sciences Ctr./Univ. of Arizona (United States)
Mark Allen Neifeld, Optical Sciences Ctr./Univ. of Arizona (United States)
Xuewen Chen, Optical Sciences Ctr./Univ. of Arizona (United States)

Published in SPIE Proceedings Vol. 4089:
Optics in Computing 2000
Roger A. Lessard; Tigran V. Galstian, Editor(s)

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