RESEARCH OF MULTI-WAVELENGTH READ-OUT FOR MULTILAYERED MO DISK

为了实现超高密度磁光磁盘，提出了一种磁多值（MMV）磁光磁盘的多波长读出（MWR）方法。采用MWR方法可以提高信号的信噪比。数据传输速率也因多层的同时读出而提高。19981年的研究成果。为了实现和设计多层MO光盘，需要精确的复折射率与MO材料厚度的关系。透明MO层比常规MO层薄，其各项指标对多层体系尤为重要。然而，没有关于厚度依赖性的数据。我们揭示了TbFeCo的n和k光谱与厚度和波长的关系。利用测量到的光学特性，设计了波长为442 nm和488 nm的优化MWR双层MO光盘。这些结果将在INTERMAG' 99， korea上公布。为实现超高密度磁光盘，设计了波长为514.5 nm和780 nm双波长读出法的双层磁光盘头。通过在514.5 nm和780nm光束中分别插入透镜，光学头聚焦透镜的色差降低。利用双波长光头，在双MO层中写入信号的读出实验结果在1999年磁光记录国际学术研讨会上发表。为了提高外磁场对写入的灵敏度，我们对MO材料和磁盘层构型进行了优化。我们通过实验找到了高灵敏度MO的条件。

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 19981.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.