Epoxy-photopolymer Composite Materials for Holographic Data Storage & Study of a Novel Water-soluble Dye for Two-photon Polymerization

Abstract: The thesis comprises two parts. The first part is epoxy-photopolymer composite materials for holographic data storage. Novel materials were designed and every component’s effects on materials’holographic properties were investigated. The second part is study of a novel water-soluble dye for two-photon polymerization (TPP). A novel dye was synthesized. Its photophysical/photochemical properties and its application in TPP under aqueous system were investigated. Some valuable results are achieved.1. Novel photopolymers for holographic storage were designed and investigated by combining acrylate monomers or vinyl monomers as recording media and liquid epoxy resins plus an amine harder as binder. The thickness of samples could be controlled between 0.2 mm to 1 mm without using large amount of volatile solvents compared to traditional thin film materials.2. Different epoxy resin, amine harder, monomers, and dyes were chosen for optimizing samples’holographic properties including optical quality, diffraction efficiency, sensitivity, refractive index modulation, 3dB LSNR exposure dose, and shrinkage. The effects of samples’components, thickness and preparation procedure on their performance were discovered. Several instructive conclusions were obtained.3. With an optimized components and preparation procedure, samples with high qualities were prepared. Diffraction efficiency of above 60%, refractive index modulation of above 3.0×10~(-4), sensitivity of 0.3 cm/mJ, and shrinkage of 0.5% were obtained. It shows that the quality of our samples were comparable to import commercial ones. Furthermore, a signal-to-noise ratio of 3 dB after once write and retrieve was achieved in holographic storage experiments, indicating that these materials would have promising application in high-density holographic storage.4. A novel water-soluble benzylidene cyclopentanone dye (BSEA) was synthesized. Its two-photon absorption (TPA) cross-section in water was determined by nonlinear transmission method with Ti:sapphire femtosecond laser as exciting light source. 287 GM at 800 nm was obtained, which is quiet larger than TPA cross-section of water-soluble xanthene dyes. Using this new dye as initiator, two-photon polymerization (TPP) of water-soluble acrylate could be induced directly. Low threshold energy of 0.51 mW and a high resolution of 400 nm were achieved, indicating this dye would have extensive application prospects in TPP in aqueous system…
Key words: photopolymer; holographic property; water-soluble dye; two-photon polymerization

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