Phase-image-based sparse-gray-level data pages for holographic data storage

Abstract

We propose a method for implementation of gray-scale sparse block modulation codes with a single spatial light modulator in phase mode for holographic data storage. Sparse data pages promise higher recording densities with reduced consumption of the dynamic range of the recording material and reduced interpixel cross talk. A balanced sparse-gray-level phase data page gives a homogenized Fourier spectrum that improves the interference efficiency between the signal and the reference beams. Construction rules for sparse three-gray-level phase data pages, readout methods, and interpixel cross talk are discussed extensively. We also explore theoretically the potential storage density improvement while using low-pass filtering and sparse-gray-level phase data pages for holographic storage, and demonstrate the trade-off between code rate, block length, and estimated capacity gain.