Two-Dimensional Modulation for Holographic Data Storage Systems

Abstract

Page-oriented holographic data storage systems (HDSSs) generally use spatial light modulators (SLMs) to generate twodimensional (2D) digital patterns, so-called data pages. These data pages are stored via interference patterns of the object and reference beam in the holographic medium and are retrieved from the medium by exposing it to the reference beam. The reconstructed data pages are then detected by a matrix detector. One important challenge in designing an HDSS is to develop a suitable modulation, which takes into account the specific characteristics of the transfer channel and enables high data capacity, high data transfer rate and low symbol error rate (SER). In this paper, we present a new method for modulating data in an HDSS. The main idea is to adapt the general concept of 2D run-length limited modulation (RLL) to a numerically more efficient implementation usable for HDSS. We demonstrate that this 2D block coding method with a constant weight and a sparse code increases the amount of user data per data page, while the SER remains low compared with standard sparse modulation coding. This results in a higher data rate and higher data density.

Data Detection Methods for Holographic Data Storage Systems

“…In this paper, we restrict our discussion on block modulation codes with a constant white rate and compare a sparse code with a balanced code -in our case, involving 4 Â 4 blocks with three or eight on-pixels. 8) This indicates a restriction to binary data pages not considering gray-scale modulation schemes.…”

“…This method is based on the correlation detection (see an example in the publication of Motoyama et al 7) ) of pseudo-random patterns with a white rate equal to the block modulation white rate and with a size of 2 Â 2 data blocks. 8) The second step of the data detection procedure is decimation. In our case, decimation means the geometric transformation of the detector data area into the size of the original SLM data area.…”

Modulation Codes for Optical Data Storage

“…One constraint sets upper and lower bounds to run-length of zeros in both horizontal and vertical directions (Kamabe, 2007). The other one sets upper and lower bounds to 2-D spatial distance between any two ON pixels (Malki et al, 2008;Roth et al, 2001). See Fig.…”

“…In (Malki et al, 2008), a fixed number of all-ON sub-blocks are present in each code block. This scheme lets the proposed code comply with the constant-weight constraint automatically.…”

Iterative Decoding between Two-Dimensional Soft Output Viterbi Algorithm and Error Correcting Modulation Code for Holographic Data Storage

“…1,2) In order to reduce 2D ISI, researches have been conducted to eliminate fatal isolated patterns (i.e., where the pattern is surrounded by different pixels). [3][4][5][6][7] However, they do not have extra coding gain, unlike modulation codes with a trellis structure. [8][9][10] In particular, Kim et al introduced an error correcting the modulation code for holographic data storage.…”