Kinetics And Storage Characteristics Of Holographic Gratings In Photopolymers

As one of the most promising materials for high density holographic storage, photopolymer has great advantages:high diffraction efficiency,wide dynamic range, real-time dry processing and low cost,which has become the hot topic of research in recent years.The research on photopolymer is developing rapidly in foreign country, but it is still at the beginning stage in our country,which involves mainly in experimental investigations on the measurement of holographic characteristics of materials.There are only a few reports of the study on the formation of holographic gratings in the photopolymer.Based on the summarizing of the research and progress of holographic storage and photopolymers,the following studies are included in the thesis on the photochemical mechanism,the monomer diffusion model,kinetic parameters and holographic characteristics of arcylamide-based photopolymers.1.The principle of photochemistry and the diffusion theory in the photopolymer are studied.The dynamic development process of holographic gratings is discussed and the dynamic theoretical model of hologram formation is established.The influence of kinetic parameters in the model is also analyzed on holographic storage characteristics.2.An erythrosine B sensitized photopolymer for holographic storage is prepared. The influence of the exposure intensity and concentration of dye is analyzied on holographic characteristics of materials in the experiment.3.By means of fitting the experimental data of transmittance and diffraction efficiency as a function of time,we have obtained several dynamic parameters,such as the molar absorption coefficientε,the quantum yieldφ,the photobleaching coefficient k_p,the polymerization rate k₀ and the diffusion time constantÏ„_D.The variation of them with different concentrations of dye and exposure intensities is presented. 4.A multi-wavelength visible light sensitive photopolymer is prepared for holographic storage.The holographic characteristics of materials are respectively obtained under single wavelength and multi-wavelength.The influence factors of them are also analyzed.5.The Raman spectras of components of materials are analyzed in the experiment. The Raman spectrometry is used for real-time monitoring of the photochemical reactions in a methylene blue sensitized photopolymer.The polymerization rate constants of materials are educed.