| Abstract
| - Optically transparent thick films of methacrylate copolymer containing donor−acceptor-type azobenzene andcyanobiphenyl moieties were prepared, and their optical properties were explored in terms of a photoinduced changein molecular alignment and the formation of Bragg gratings with angular and polarization multiplicity. Azobenzenemoieties substituted with ethoxy, cyano, and nitro groups were employed, and their photoresponsive behavior wasinvestigated. It was found by polarized UV−vis spectroscopy that the alignment of azobenzene moieties in the filmswas random in the initial state but became perpendicular to the direction of polarization of the writing beam afterirradiation with a linearly polarized beam from an Ar+ laser at 514 nm. The film containing the cyanoazobenzenemoieties showed the fastest formation of optical anisotropy due to an efficient change in molecular alignment. Whentwo linearly polarized beams from the Ar+ laser were allowed to interfere in the films with a thickness of 200 μm,the diffraction beam was observed immediately and reached 97% upon photoirradiation at 200 mW/cm2 for 5 min.It was clearly observed that the response time became shorter with an increase in the light intensity of the writingbeams, maintaining the high diffraction efficiency. Furthermore, it was clearly seen that the diffraction efficiencystrongly depended on the direction of polarization of the reading beam. Holographic multiple data storage in a filmwas demonstrated, and 55 holograms with angular multiplicity were recorded successfully. In addition, multiple datastorage using the polarization and angle selectivity simultaneously was first demonstrated.
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