Wavelength dependence of optical characteristics for TbFeCo and MO disk structure for double-wavelength readout MO disk

Multi-wavelength readout (MWR) for multi-layered magneto-optical (MO) disks has been proposed for a high density MO recording. For achieving and designing the multi-layered MO disk, the dependencies of the exact 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 a multi-layered system. However, there are no data for those dependencies on thickness. We studied the dependencies on thickness and wavelength. By applying the measured optical characteristics, an optimized MWR double-layered MO disk is designed for 442 and 488 nm in wavelength