1998 Fiscal Year Final Research Report Summary
RESEARCH OF MULTI-WAVELENGTH READ-OUT FOR MULTILAYERED MO DISK
| Project/Area Number |
09650391
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
電子デバイス・機器工学
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| Research Institution | Nihon University |
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Principal Investigator |
NAKAGAWA Katsuji Nihon University, College of Science and Technology, Associate Professor, 理工学部, 助教授 (20221442)
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| Co-Investigator(Kenkyū-buntansha) |
ITOH Akiyoshi Nihon University, College of Science and Technology, Professor, 理工学部, 教授 (60059962)
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| Project Period (FY) |
1997 – 1998
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| Keywords | MAGNETO-OPTICAL RECORDING / MULTI-WAVELENGTHS / OPTICAL MEMORY |
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| Research Abstract |
For achieving super high density magneto-optical (MO) disk, we proposed a multi-wavelength readout (MWR) method for magnetic multi-valued (MMV) MO disk. By using the MWR method, the signal to noise ratio (SNR) can be increased. The data transfer rate is also increased by the simultaneous readout for the multi layer.
Research results for 1998
1.For achieving and designing the multi-layered MO disk, the dependencies of theexact complex refractive indices on thickness for MO materials are necessary. The indices for the transparent MO layer, which is thinner than the conventional MO layer, is especially important for the multi-layered system. However, there are no data for those dependencies on thickness. We revealed the dependencies of the spectra of n and k for TbFeCo on thickness and wavelength. By applying the measured optical characteristics, one of the optimized MWR double-layered MO disk was designed for 442 and 488 nm in wavelength. These results will be report at the INTERMAG' 99, KOREA.
2.An optical head of the double-wavelength readout method for 514.5 and 780 nm in wavelength was designed for a double-layered magneto-optical (MO) disk for achieving super high density magneto-optical disk. The chromatic aberration of the focus lens in the optical head was decreased by inserting lenses in the each beam for 514.5 and 780nm lights. By using the double-wavelength optical head, the results of readout experiments of signals which were written in the double MO layers were represented at the Magneto-Optical Recording International Symposium (MORIS '99).
3.To increase the sensitivity for the external magnetic field for writing, we optimized the MO materials and the layer configuration of the disks. We found the condition for the high sensitivity MO, experimentally.
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