Two-Dimensional 5:8 Modulation Code for Holographic Data Storage

We present a two-dimensional (2D) 5:8 modulation code which does not allow isolated pixel patterns for holographic data storage. We compare it with 6:8 code and uncoded cases. Bit error rates (BERs) are measured by the threshold detection and the 2D soft-output Viterbi algorithm (SOYA) collaborated with 2D equalizer at the blur of 1.85. The proposed 2D 5:8 modulation code is simpler than conventional 6:8 code and removes all the isolated 2D ISI patterns. As a result, when the 2D SOVA is applied and the data is quantized to 1 or 2 bits, the SNR of the proposed 5:8 code is approximately 3 dB better than that of the 6:8 code at 10(-5) BER. When the data is quantized to 3 or 4 bits, both codes show similar performance. (C) 2009 The Japan Society of Applied Physics DOI: 10.1143/JJAP.48.03A031