Two-dimensional finite-difference time-domain simulation for rewritable optical disk surface structure design

A novel two-dimensional finite-difference time-domain simulation for treating the interaction of a focused beam with a rewritable optical disk is detailed and experimentally validated. In this simulation, the real material properties of the rewritable multilayer stack and the aperiodic nature of the disk topography are considered. Excellent agreement is obtained between calculated and measured push-pull tracking servosignals for magneto-optical disks with pregrooves and infinite-length preformat pits. To demonstrate the utility of the simulation as a design tool, the design process for a 0.9-µm track pitch, continuous, composite servoformat magneto-optical disk is given.