Advanced channel modeling of holographic data storage considering degradation shapes of reconstructed image

Page-based holographic data storage (HDS) is very sensitive to disturbances such as tilt and media positioning because of extremely high density of HDS. As a result, reconstructed images are also affected by disturbances, which is represented as degradation of image and signal-to-noise ratio (SNR). Therefore, it is important to detect and compensate the disturbances of HDS. In order to detect and compensate the disturbances, there have been many researches using degradation shapes of reconstructed image. However, it is hard to obtain and analyze the degradation shapes because complex and iterative experiments are required. Furthermore, experiments also have to be done for applying detection and compensation algorithms. Because of inefficiency of experiments, channel model of HDS which can model degradation shapes with respect to disturbances is important. Channel model can reduce the number of experiment and improve efficiency of research. In previous research, channel model of holographic data storage was proposed, but detailed description of the mathematical model and degradation shapes with respect to disturbances direction and amplitude were not modeled. In this paper, advanced channel model which is possible to model degradation shapes is proposed. Proposed channel model considers three causes which effect to media positioning and tilt: Bragg mismatch, imperfect phase conjugation, and media deformation due to temperature. In order to represent degradation of diffraction efficiency caused by Bragg mismatch and media deformation, k-sphere model whose vector concept is expanded to field to use in overall data page with each signal vectors revised by Rodrigues rotation formula is applied.