Modelling thermal diffusion of scanned and focused laser power on direct overwrite magneto-optical disk

For high data density recording with mark edge recording, for example, 0.56 μm/bit which has been proposed for the next generation standard (NGS) Magneto-Optical (MO) disk, thermal interference in forming mark edges should be pre compensated [1] or should be made uniform (i.e. not dependent on the data pattern recorded on the disk). Meanwhile, direct overwrite (DOW) is an indispensable function for the NGS MO disk for rewritable multi-media applications [2]. We, therefore, report that thermal diffusion of scanned and focused laser power on DOW-MO disk could be analyzed with a simplified analytical model which has three main fitting parameters, the specific heat: Cp [J/°C ·m³], the thermal diffusivity: [m²/sec], and the adiabatic index: n [anonymous dimensionless] of the resin sandwiching both the dielectric and MO thin film constituting the DOW-MO disk. The model is useful to predict the thermal interference in forming mark edges on the DOW-MO disk.