Improved multiplexing density in volume holographic memories through beam apodization

Brian M. King, Mark A. Neifeld, Xue wen Chen

Research output: Contribution to journalConference article

1 Scopus citations

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/#.

Original languageEnglish (US)
Pages (from-to)132-137
Number of pages6
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume4089
StatePublished - Jan 1 2000
EventOptics in Computing 2000 - Quebec City, Can
Duration: Jun 18 2000Jun 23 2000

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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