In this paper, we report our investigations on thick holographic recording material of the phenanthrenequinone doped poly(methyl methacrylate) (PQ:PMMA) photopolymer. The design strategy and fabrication technique for making thick polymer samples with negligible shrinkage and good optical quality are presented. The physical mechanism for holographic recording in PQ:PMMA material is described, and methods for improving are proposed. Based on these methods, photopolymer samples with different compositions are fabricated and experimentally characterized. The results show that by modifying compositions, the material sensitivity and dynamic range for volume holographic recording have been improved.

Based on a vector wave theory of volume holograms, dependence of holographic reconstruction on the polarization states of the writing and reading beams is discussed. It is found that under paraxial approximation the circular polarization holograms provide a better distinction of the reading beams. Characteristics of recording polarization holograms in thick phenanthrenequinone-doped poly(methyl methacrylate) (PQ/PMMA) photopolymer are experimentally investigated. It is found that the circular polarization holographic recording possesses better dynamic range and material sensitivity, and a uniform spatial frequency response over a wide range. The performance is comparable to that of the intensity holographic recording in PQ/PMMA. Based on theoretical analyses and the material properties, a polarization multiplexing holographic memory using circularly polarization recording configuration for increasing storage capacity has been designed and experimentally demonstrated.

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We fabricate two phenanthrenequinone-doped copolymers which can improve the holographic recording characteristics of phenanthrenequinone-doped poly(methyl-methacrylate) (PQ/PMMA) photopolymer. In these materials, the polymer matrix of PQ/PMMA is modified to be copolymers, which composed of either poly(methyl-methacrylate-co -trimethylolpropane-triacrylate) or poly(methyl-methacrylate-co-acrylic acid 2-phenoxyethyl ester), respectively. With the chemical analyses of these materials before and after light exposure, we investigate the physical mechanism of the holographic recording in those copolymer samples. In addition, the holographic characteristics of different samples, including dynamic range and sensitivity, have been measured. These experimental results demonstrate that modification of the monomers is an efficient method to improve the material properties.

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