Thermal modeling of phase change optical recording disk

Abstract

Erasable phase change recording is an emerging technology for achieving high density data storage. In the case of phase change optical disks, recording and erasing are achieved by the crystllographic structure changes of thin films when the films are heated by laser irradiation. Reproduction of the recorded information is performed by detecting the reflectivity changes caused by the differences in optical constants between the crystalline and the amorphous states. The amorphous state is realized by heating the material film with sufficient laser irradiation power to melt the material over its melting point, and rapidly quenching it to room temperature. The crystalline state is achieved by annealing the film at a temperature between the crystallizing temperature and the melting point. Thus, the calculation of the temperature distribution and the determination of the influence of factors such as media composition, laser power, duty cycle and scanning speed, and disk layer structure are important issues to be considered when attempting to improve the quality of optical disk recordings.