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HOME > No.13, May 2018 > First Step towards Practical Aapplication of Holographic Memory with Magnetic Assistance

First Step towards Practical Application of Holographic Memory with Magnetic Assistance

Error-free data recording and reconstruction with magnetic-holographic memory By Yuichi Nakamura
Associate Prof. Nakamura (right) and the first author, Ph.D candidate, Zen Shirakashi.

Yuichi Nakamura, Associate professor at Toyohashi University of Technology, and his group, are the first in the world to have successfully applied magnetically assisted recording to magnetic-holographic memory to reduce recording energy consumption and achieve error-free data reconstruction. This new technology may potentially allow for the practical application of magnetic-holographic memory as a rewritable, ultra-high-density and high-speed optical information storage medium.

In recent years the volume of information being distributed across the world has sharply risen due to new technologies such as high-speed with mass date transfer of the Internet and 8K broadcasting. In response to this trend, there is increasing demand for an innovative method for storing large volumes of data at ultra-high recording density and at ultra-high speed. Magnetic-holographic memory is one type of technology apparently capable of meeting this demand, since it can be used to record 1 TB worth of data (equivalent to the total capacity of 40 Blu-ray discs, each with a typical capacity of 25 GB) on a disc the size of a DVD or Blu-ray disc.

In magnetic hologram recording, a medium is magnetized in one direction; then the medium is irradiated with an information-bearing beam (signal beam) and a reference beam; and the resulting interference pattern is recorded in the form of the difference in magnetization directions. When this recording proceeds with an external magnetic field applied to it, the recording of the difference in magnetization directions becomes clearer. The latter process is called magnetically assisted recording.

The research group led by Yuichi Nakamura has applied this magnetically assisted recording technology to magnetic-holographic memory and, for the first time in the world, succeeded in reducing recording energy consumption and achieving error-free data reconstruction.

Fig.1 Reconstructed image with and without magnetic

Through simulation, the group investigated the size of the stray magnetic field required for magnetization reversal in magnetic hologram recording. As a result, they found that the thinner the medium, the smaller the necessary stray magnetic field and the less clear the hologram recording. They also proved through experiments that magnetically assisted recording yields a clear magnetic hologram even with a thin medium, and the magnetic hologram yields a bright reconstruction beam upon irradiation with a reference beam. Through further experiments, they found that magnetically assisted recording and reconstruction of two-dimensional data yields clear reconstruction images. As a result of this research, the group have achieved a world first by managing a significant reduction in errors in data recording and reconstruction for low energy consumption as well as error-free recording and reconstruction with magnetic-holographic memory.

"Until now it has been difficult to obtain a clear reconstruction image with a magnetic hologram, due to strict requirements for material characteristics, optical conditions, and so on. Using magnetically assisted recording, we have relaxed these requirements and also improved the reconstruction performance of recording media. This technology is promising for the future application of magnetic-holographic memory," says first author Shirakashi.

The research group intends to proceed with their work to improve recording density, and their goal is to apply this technology to make a portable, ultra-high-density and high-speed optical information storage medium (outperforming Blu-ray discs) capable of storing high-volume contents from various sources including 8K Super Hi-Vision broadcasting and 3D films; and to enable wide application of this technology in various types of storage systems, including archive and cold storage for storing information such as medical image data, SNS data on the Internet, and high-volume data in data centers.

This work was supported in part by Grants-in-Aid for Scientific Research (S) 26220902 and (A) 15H02240.


Zen Shirakashi, Taichi Goto, Hiroyuki Takagi, Yuichi Nakamura, Pang Boey Lim, Hironaga Uchida & Mitsuteru Inoue, “Reconstruction of non-error magnetic hologram data by magnetic assist recording” Scientific Reports,7, Article number: 12835 (2017).


By 中村 雄一


近年、インターネットや8K放送をはじめ、世の中に流通する情報は増え続けており、そうした大容量データを超高記録密度・超高速で保管する革新的な技術が求められています。磁気ホログラムメモリはそうした要求を満たす技術の1つであり、DVDやBlu-ray Discと同じサイズのディスクに1TB(通常の容量25 GBのBlu-rayディスク40枚分)を超える情報を記録できる技術です。






本研究の一部は科学研究費補助金 基盤(S) 26220902 および 基盤(A) 15H02240の補助を受けて実施しました。

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Researcher Profile

Yuichi Nakamura
Name Yuichi Nakamura
Affiliation Department of Electrical and Electronic Information Engineering
Title Associate Professor
Fields of Research Thermoelectric materials and engineering / Spin caloritronics / Magnetic hologram memory / Electrical and electronic materials / Materials processing