Diffraction Efficiency of Volumetric Magnetic Holograms with Magnetophotonic Crystals

抄録

  Hologram memory is a promising data storage technology with a high recording density and fast data-transfer rate. Magnetic garnet media such as Bi_1.3Dy_0.85Y_0.85Fe_3.8Al_1.2O₁₂ (substituted rare-earth iron garnet, SRIG) films have advantages of rewritability and unnecessity of shielding. The diffraction efficiency of these garnet films, however, is not sufficient to apply to storage devices. In this paper, we proposed a use of magnetophotonic crystals (MPC) as hologram media and calculated their diffraction efficiency. The results indicated that MPC media showed a high diffraction efficiency compared with single SRIG films, and especially the MPC medium with the structure of substituted gadolinium gallium garnet substrate / (Ta₂O₅ / SiO₂)² / SRIG / (SiO₂ / Ta₂O₅)² with the SRIG thickness of 3.88 μm exhibited the diffraction efficiency of 0.36%. A large Faraday rotation angle and deep magnetic hologram fringe originated from the localization of light results in such a high diffraction efficiency.