Abstract
Holographic memory is a strong candidate for next-generation optical storage, featuring high recording densities and data transfer rates, and magnetic hologram memory using a magnetic garnet, as the recording material is expected to be used as a rewritable and stable storage technology. However, the diffraction efficiency of magnetic holography depending on the Faraday rotation angle is insufficiently high for actual storage devices. To increase the diffraction efficiency, it is important to record deep magnetic fringes, whereas it is necessary to suppress the merging of fringes owing to heat diffusion near the medium surface. In this work, we investigated the recording process of magnetic holograms in detail with experiments and numerical simulations, and developed a multilayer media with transparent heat dissipation layers to record deep and clear magnetic holograms by controlling the heat diffusion generated during the thermomagnetic recording process. To suppress lateral heat diffusion near the medium surface, we designed and fabricated a multilayer magnetic medium in which the recording magnetic layers are discrete in a film, approximately 12-µm thick. This medium exhibited diffraction efficiency higher than that of the single-layer medium, and error-free recording and reconstruction were achieved using the magnetic assist technique.
Highlights
Holographic memory has been attracting attention as a data-storage technology with high recording density and data transfer rates because two-dimensional (2D) page data can be recorded and read selectively from a single position [1,2,3,4,5,6,7,8,9,10,11]
A simple design method for heat dissipation (HD) multilayer effective for diffusing the excess heat from the garnet layers into the HD layers (HDLs) [25]. In this media was developed, and the HD multilayer medium was fabricated. Using this HD multilayer study, we investigated in detail the recording process of magnetic holograms in garnet media with experiments and numerical simulations in order to improve diffraction efficiency through forming deep and clear magnetic fringes
We investigated in detail the recording process of magnetic holograms in garnet media to achieve high diffraction efficiencies through the formation of deep and clear magnetic holograms
Summary
Holographic memory has been attracting attention as a data-storage technology with high recording density and data transfer rates because two-dimensional (2D) page data can be recorded and read selectively from a single position [1,2,3,4,5,6,7,8,9,10,11]. The Holographic Versatile Disk is an international standard for holographic memory and employs a collinear holographic system that can write and read data using a single optical axis with a spatial light modulator as the key device [12,13,14]. The magnetic hologram is a candidate for rewritable holograms and exhibits a high material stability, in which the interference patterns of light can be recorded as differences in the direction of magnetization; interference patterns have been recorded on thin films of
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