Erasable Optical Disks for Data Storage: Principles and Applications

Erasable optical disk storage systems offering densities in excess of 10⁸ bits/cm² using thermomagnetic recording and magnetooptic readout are described and compared to conventional magnetic disks. The preparation and properties of amorphous rare earth-transition metal alloy thin films, which serve as the recording media, are also presented. The lack of a strong readout signal suggests the need for the enhancement of the signal-to-noise ratio (SNR). A multilayering scheme with improved SNR and superior thermal characteristics is discussed. Potential research and development issues are also indicated.