Jiro Yoshinari

A New Class of Photopolymer for Holographic Data Storage Media Based on Organometallic Matrix

New photopolymer materials were prepared with a view to achieving holographic data storage media of large dynamic range. For this purpose, organometallic compounds of high refractive index were used as a matrix, and organic compounds as photosensitive monomers. The organometallic matrix was obtained from transition metal– and silicon–alkoxides by modifying the sol–gel process. The matrix was combined with low refractive index monomers, and then the mixture was filled between glass substrates to fabricate recording media. These media showed M-number (M/#) of about 42 to 64 (per 1 mm thickness) when evaluated by a plane-wave tester equipped with a 407 nm laser diode. As for the sample which gave M/# of approximately 42, a raw data density of 76 Gbit/in.2 was achievable upon multiplex page-data recording by a coaxial optical system, in which a page-data volume was 56.8 kbit/page. In another experimental result, optimization of monomer structures brought about a shrinkage ratio of 0.08% as a mechanical volume change.

Magnetic structure analysis of multilayered oblique-evaporated tape

Abstract Multilayered oblique-evaporated tapes have been developed which have higher residual magnetization with high coercivity, and can exhibit excellent recording characteristics in comparison with single-layered tapes. The magnetic structured of a double-layered model was calculated under the condition of the minimization of its magnetic energy on the basis of the coherent rotation model including interlayer interactions. Through this analysis, it was found that the multilayered tape of this model can achieve high saturation magnetization whilst retaining a high coercivity by the interlayer interaction, even in a state of high column angle. It is understood that the multilayered tape has more excellent recording characteristics over a wide frequency range than single-layered tape through this results.