| Holographic data storage is considered as a very promising method to replace the existing optical disc storage technology. It can reach a very fast transfer rate and a high storage density. The development of holographic storage media is a key factor to constrain the commercialization of holographic storage devices. Organic photochromic dye-doped polymer media, with a rewritable, high-resolution, low price, fast response and other characteristics, attracted great deal of attention in holographic storage. Spirooxazine (SO) is a kind of photochromic compound with a high thermal stability and fatigue resistance. Spirooxazine occurs in the C-O bond cleavage irradiated by ultraviolet (UV) light, transformed from colorless spiro structure into a colored open merocyanine structure; while merocyanine molecules can revert to the initial spiro forms photochemically or thermally. Spiro structure molecules have a poor nonlinear optical property, while merocyanine molecules have better due to its non-centro-symmetric structures. Its electric dipole moment is one of the biggest several categories among the known organic compounds.In the thesis, two different spirooxazine compounds (SO1 and SO2) were synthesized rapidly through microwave method. Spirooxazines doped poly methyl methacrylate (S01(2)/PMMA) thin films as a holographic storage medium (memory medium) were fabricated, prepared by spin-coating. The research work was divided into four parts:1. Photochromism. The absorption spectra of two kinds of memory media (SO1(2)/PMMA) were measured with UV-Visible spectrophotometer. Thermal rate constants were obtained through the two-level energy model fitting, indicating that the thermal stabilities of the two memory media exit significant difference. Fluorescence characteristics of two kinds of memory media pre-irradiated by UV light were measured with the spectrofluorometer. The effects of thermal stability on the fluorescence spectra versus time were analyzed.2. Photo-induced anisotropy. Photo-induced anisotropy is characterized as photo-induced birefringence of SO1/PMMA memory medium measured by pump-probe method. Dynamics of photo-induced anisotropy was explained by Angular Hole Burning (AHB), Angular Redistribution (AR) and Angular Diffusion (AD). When the pumping beam irradiated the memory medium, the effect of AHB on the photo-induced birefringence is dominant at first, then that of AR become stronger. While, driven by thermal randomization, the effect of AD on the photo-induced birefringence is obvious. Based on the analysis above, a photo-induced anisotropy kinetic equation for SO1/PMMA memory medium was established, proposing the dual role of photo-orientation and photo- isomerization of the pumping beams. The competition of photo-orientation and thermal randomization was also described. The model well explained the temporal evolution of photo-induced birefringence relative to pumping beam intensity and polarization angular. We also point out that Constant Model only fits to the low power irradiation, while Thermal Effect Model is suitable for the high power irradiation.3. Polarization holography. Polarization holographic gratings were classified and mathematically described by Jones matrix. The general expressions of diffraction efficiency in different interference patterns were derived. We qualitatively point out the trend of the diffraction efficiency dynamics, We presented the experimental results of S-S and S-P polarization holographic recording and that of erasure process of S-S holographic grating in SO1(2)/PMMA memory media, under UV light irradiation. The phenomenological equation curves agree well with the experimental results. It was pointed out that the grating growth dynamics is controlled by the competition between orientation and isomerization. For the SO1/PMMA memory medium, the S-S holographic grating erase contains the formation of transient orientation grating.4. Optical switch. Optical signal of SO1/PMMA memory medium was controlled effectively by the intensity and polarization of pumping beams, indicating that the application of the memory medium in all-optical switching device exist possibility in the future.Finally, the research work was summarized. The prospects for further work were also proposed.
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