Speckle-shift multiplexing along axial direction in reflection-type holographic memory

in reflection-type holographic memory, speckle-shift multiple recording along the axial direction of a storage medium is investigated experimentally and numerically. We record three data pages along the axial direction of an iron-doped lithium niobate medium with a thickness of 0.5 mm and an interval of the first null distance of shift selectivity, and each hologram was read out at the recording position. We also numerically evaluate the multiple recording along the axial direction. The numerical analysis supports the fact that the speckle size determines the three-dimensional recording interval. The numerical results are in qualitative agreement with the experimental results. We numerically examine the bit error rate as a function of the recording interval. The results show that multiplexing along the axial direction can increase the storage capacity.