Applying digital filter to data pages before recording to increase signal-to-noise ratio in holographic memory

Abstract

The spatial filter in the path of the signal and reconstructed beams and the sampling of reproduced data pages on a camera cause a nonuniform brightness distribution of bright symbols and degrade the signal-to-noise ratio (SNR). We thus applied a digital filter to data pages before recording to improve the reproduced data quality. The simulation results showed that a digital filter with coefficients of the neighboring horizontal and vertical taps from the center tap of −0.10 improved the brightness distribution of bright symbols and increased the SNR of the reproduced data. We experimentally investigated the effect of the digital filter in angle-multiplexed holograms. As a result, the SNR increased and the bit error rate decreased. We found that this method is effective for improving the reproduced data quality.