2-D Signal Processing and Coding for Digital Page-Oriented Memories

Digital page-oriented Volume Holographic Storage (VHS) is a promising digital storage technology because of its high data storage density, high data rate and short access times. As the storage density increases, the performance of volume holographic storage channels is degraded due to increased two- dimensional (2-D) intersymbol interference (ISI) and noise. The output detector array in VHS detects the intensity of the incident light wave-front leading to sign information loss. This sign loss precludes the applicability of conventional equalization/detection schemes to mitigate ISI. In this book, we first address channel modeling under the quadratic nonlinearity and then develop 2-D equalization/detection methods such as linear minimum mean square (LMMSE) equalization, iterative magnitude square decision feed back equalization (IMS¬DFE) and partial response maximum likelihood (PRML) to mitigate 2-D ISI under quadratic nonlinearity. We also evalu¬ate the effect of modulation coding, particularly balanced codes and low pass coding. We finally investigate the performances of the equalization/detection methods under optical magnification error.