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.