Gray-scale data pages for digital holographic data storage

Geoffrey W. Burr, Gabriele Barking, Hans Coufal, John A. Hoffnagle, C. Michael Jefferson, Mark A. Neifeld

Research output: Contribution to journalArticlepeer-review

37 Scopus citations


The prospects for gray-scale (or multilevel) digital holographic data storage are theoretically and experimentally investigated. A simple signal-to-noise ratio (SNR) partitioning argument shows that when SNR scales as 1 over the number of holograms squared, five gray levels (log2 5 bits/pixel) would be expected to result in a 15% capacity increase over binary data pages. However, the additional signal-dependent noise sources present in practical systems create a baseline SNR that reduces both the optimal number of gray levels and the resulting gain in capacity. To implement gray-scale recording experimentally, we adapt the predistortion technique previously developed for binary page-oriented memories [Opt. Lett. 23, 289 (1998)]. Several new block-based modulation codes for decoding gray-scale data pages are introduced. User capacity is evaluated by an experimental technique using LiNbO3:Fe in the 90° geometry. Experimental results show that a balanced modulation code with three gray levels provides a 30% increase in capacity (as well as a 30% increase in readout rate) over local binary thresholding.

Original languageEnglish (US)
Pages (from-to)1218-1220
Number of pages3
JournalOptics letters
Issue number15
StatePublished - Aug 1 1998

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


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