Motohiko Hidaka

Highly transparent ZrO 2 nanoparticle-dispersed acrylate photopolymers for volume holographic recording

We demonstrate and characterize volume holographic recording in ZrO(2) nanoparticle-dispersed acrylate photopolymer films that have very low scattering loss. More than thirty-fold reduction in the scattering coefficient, as compared with those of previously reported TiO(2) nanoparticle-dispersed photopolymers, is achieved. It is shown that the refractive index modulation as high as 5.3x10(-3), together with substantive photopolymerization-shrinkage suppression, is obtained at the nanoparticle concentration of 15 vol.%. Dependences of nanoparticle concentration and grating spacing on the refractive index modulation are also investigated.

Organic nanoparticle (hyperbranched polymer)-dispersed photopolymers for volume holographic storage

We report on the use of hyperbranched polymers (HBPs) acting as mobile organic nanoparticles doped in methacrylate photopolymers for highly efficient volume holographic recording. Two types of reduced HBPs having the average size of 10nm are synthesized. The diffraction efficiency near 100% in the green (532nm) and substantive polymerization-shrinkage suppression in this photopolymer system are demonstrated. Periodic assembly of HBPs under holographic exposure is also observed.

Volume holographic recording in multicomponent photopolymers with hyperbranched polymers as organic nanoparticles

We describe the diffraction properties of organic nanoparticle-dispersed photopolymers in which hyperbranched polymers (HBPs) act as transporting organic nanoparticles that increase the refractive-index contrast of a hologram. We prepared HBPs by the living radical vinyl polymerization of inimers under ultraviolet-light illumination. Such synthesized HBPs are easy to disperse into monomers without any aggregation, so that samples with good optical quality are available. We investigate the role of HBPs in the recording process for two different types of photopolymers capable of radical polymerization and cationic ring-opening polymerization. We also evaluate the effect of HBP dispersion on recording sensitivities and polymerization shrinkage.

Blue-sensitive nanoparticle-polymer composites for volume holographic recording

We report on the diffraction properties of a volume hologram recorded at a wavelength of 404 nm in a ZrO2 nanoparticle-polymer compsite film. It is found that the refractive index modulation and the material recording sensitivity are as high as 8 × 10-3 and 9000 cm/J, respectively, at the ZrO2 nanoparticle concentration of 35 vol.% and a recording intensity of 5 mW/cm2. These values are comparable to or higher than those recorded at a wavelength of 532 nm. Effects of the ZrO2 nanoparticle dispersion in acrylate monomer on the polymerization kinetics are also examined by using a photo-differential scanning calorimeter. It is found that the incorporation of ZrO2 nanoparticles increases the polymerization rate.