A STUDY OF KEY TECHNOLOGIES TO REALIZE MAGNETOOPTICAL STORAGE OF OVER7 GBYTES IN CD SIZED DISK

Recently, many types of high-density recording technologies for future MO (Magneto-Optical) storage have been reported. MSR (Magnetically In duced Super Resolution) technology is one of the most promising candid ates, and over ten types of MSR technologies have been already propose d. However, they are not well-discussed From the viewpoint of total re cording technology which would include the recording and readout metho ds, the pick-up technology and the signal processing technology. Key t echnologies for realizing MO storage of over 7 GBytes in a CD-sized di sk using a red laser are proposed, and the experimental results pertai ning to each key technology are described. The write/read characterist ics were examined for the CAD (Center Aperture Detection)-MSR disk. Fr om the characteristics of the CAD-MSR disk combined with laser pumped magnetic field modulation recording, it was shown that land/groove (0. 7 mu m width) recording with the linear density of 0.27 mu m/bit and t rack pitch below 0.7 mu m 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 Likelihoo d) technologies which are very useful to achieve a high density MO dis k. Using CAD-MSR disk combined with above technologies together, high density write/read with a bit length of 0.2 mu m and a track pitch of 0.6 mu m should be realized with using the laser of 635 nm wavelength. Applying the CAD-MSR disks to a CD sized MO disk, the capacity become s over 7 GBytes (Format efficiency: 80%), which is 20 times higher tha n 5.25 inches MO disk and 1.5 times than DVD-ROM.