| The high demand is placed on data storage technology as the information and computer technology developed more and more rapidly. The promise of a next-generation optical storage technology that offers both high-density volumetric storage and fast page-oriented output has driven recent research in holographic data storage. The researchers pay more attention to making full use of the advantages of holographic storage technology focusing on the realization of high-density, large-capacity, high data-transfer rate and improving the performances of holographic storage system. Owing to the simply optical set-up and the compatibility with the compact disc storage system, three-dimensional holographic disk storage scheme and system is more suitable for huge-capacity storage in a medium with a large area, thus is more practical. With a view to fore research field of holographic storage technology and on the basis of our research group's prevenient research work, this thesis focusing on the study of realization of high-density high-fidelity and nonvolatile holographic disk storage. What's more, the optimization of the nonvolatile holographic disk storage scheme and system were carried out in order to improve the performances of holographic disk system, thus push holographic storage technology into utility. In this thesis the effects of scattering noise on input images for holographic storage in photorefractive lithium niobate crystals have been deeply investigated by means of measurements of loss of signal-to-noise ratio (LSNR). A variety of lithium niobate crystal samples with different dopants, different doping concentrations, different annealing after growth, and used for different recording geometries are studied. More attention has been paid to the characteristics of scattering noise resulting from object beams. The experimental results show that the effect of scattering noise resulting from object beam is much more significant than that of resulting from reference beam though the intensity of object beam much weaker than that of reference beam. The effect of scattering noise in oxidized crystals is less significant than that in reduced or as-grown crystals. Comparing with transmission and 90°recording geometries, reflection geometry is less subject to the effect of scattering noise. In addition to the scattering noise resulting from the defects and impurity in the crystal, photovoltaic noise resulting from bulk photovoltaic effect is also significant in photorefractive crystals. During holographic recording the presence of photovoltaic noise results in the decay of image fidelity and the photovoltaic direct current field also bring negative impact on holographic characteristics. A practical method of suppressing photovoltaic damage in iron-doped lithium niobate crystals is proposed, in which the surfaces of the crystal are coated with transparent electric-conductive material (Indium Tin Oxide, ITO) forcing the crystal to operate in a short-circuit mode. The measurements of holographic performances of several crystal samples in both open-and short-circuit modes showed that the dynamic range (M#) of crystals increased in short-circuit mode while suppressing the photovoltaic noise. Multiplexed hologram recordings in a Fe: LiNbO3 crystal, with and without ITO coating respectively verified this increase of dynamic range. We selected a disk-type photorefractive crystal as storage media for high-density high-fidelity holographic storage by evaluating the performances and the noise level of the crystal samples. A high-resolution ratio (1024×768 pixels) space light modulator (SLM) was used as page composer in order to improve the information capacity and storage density in each data page. A high sensitivity CCD camera was used as detector so that the detection noise can be suppressed effectively. Customer-designed Fourier transform and imaging optics with short focal length provide tightly confined object beam at the crystal and good image quality in the detector array. An optimized reflection configuration avoids the detrimental scattering from the crystal surface to enter the detector. All of the above system design considerations ensure the implementation of the high-density high-fidelity holographic storage. Ten thousand data pages, each containing 768×768 pixels, have been stored in a single section of a disk-shaped, iron-doped LiNbO3 crystal using spatioangular multiplexing with a convergent spherical reference beam, resulting in an areal density of 33.7bits/μm2 and a volumetric density of 6.7Gbits/cm3. The images...
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