Recently, many types of high-density recording technologies for future MO (Magneto-Optical) storage have been reported. MSR (Magnetically Induced Super Resolution) technology is one of the most promising candidates, and over ten types of MSR technologies have been already proposed. However, they are not well-discussed from the viewpoint of total recording technology which would include the recording and readout methods, the pick-up technology and the signal processing technology. Key technologies for realizing MO storage of over 7 GBytes in a CD-sized disk using a red laser are proposed, and the experimental results pertaining to each key technology are described. The write/read characteristics were examined for the CAD (Center Aperture Detection)-MSR disk. From the characteristics of the CAD-MSR disk combined with laser pumped magnetic field modulation recording, it was shown that land/groove (0.7 µm width) recording with the linear density of 0.27 µm/bit and track pitch below 0.7 µm can be realized. It was also shown that CAD-MSR disk is well combined with an OSR (Optical Super Resolution) pick up, laser pumped read-out and PRML (Partial Response Maximum Likelihood) technologies which are very useful to achieve a high density MO disk. Using CAD-MSR disk combined with above technologies together, high density write/read with a bit length of 0.2 µm and a track pitch of 0.6 µm should be realized with using the laser of 635 nm wavelength. Applying the CAD-MSR disks to a CD sized MO disk, the capacity becomes over 7 GBytes (Format efficiency: 80%), which is 20 times higher than 5.25 inches MO disk and 1.5 times than DVD-ROM.

A standard of Advanced Storage Magneto Optical (AS-MO) having a 6 Gbyte capacity in a 120 mm-diameter single side disk was established by using a magnetically induced superresolution readout method. Transition from in-plane to perpendicular magnetization for exchange-coupled readout layer (GdFeCo) and in-plane magnetization mask layer (GdFe) of the AS-MO disk has been investigated using the noncontinuous model. The readout resolution was sensitive to the thickness of the readout layer. To evaluate readout characteristics of AS-MO disks, the simulation using micro magnetics model was performed and the readout layers were designed. The readout characteristics of the AS-MO disk is improved by making the readout layer thinner.