Simulations of Marks Formed on Phase-change, Land/Groove Disks*

Finite-difference time-domain (FDTD) simulation was used to determine the amount of absorption of light propagating inside a land/groove optical disk. The results showed that three-dimensional geometry influenced absorption. Furthermore, heat conduction inside the disk depended on its geometry, so the temperature profiles of land and groove tracks were not equal. Therefore, the spatial and historic profiles of temperature must be investigated in three dimensions. These temperature profiles can then be input into a phase-change simulator in order to carry out a simulation of the process of writing marks in land and groove tracks. To predict the optical and thermal effects of a land/groove structure on the writing process, we integrated an FDTD and phase-change simulation. The integrated simulation effectively evaluated the differences between the marks formed in land and groove tracks. As well, we applied the FDTD simulation to a blue-laser recording and found that groove-track recording showed higher light convergence than land-track recording. This inclination was explained the convex/concave effect of the structure of the disk surface.