Analysis of beam wave scattering by recording marks on phase-change optical disk using boundary element method with finite element method

Two-dimensional numerical solutions for electromagnetic fields are presente d for scattering by grooves and recording marks on rewritable phase-change optical disks with multilayered structure. The boundary element method (BEM ) combined with the finite element method (FEM) can be applied to the scatt ering analysis of various groove forms and recording marks for different co nditions of the incident beam. Recording marks are represented by an area w ith an altered refractive index in the multilayered structure. Near and sca ttered far field characteristics from grooves having trapezoidal cross sect ion are studied for different polarizations of incident beam waves. Charact eristics of read-out signals are also calculated as functions of groove hei ght and film thickness of the multilayer. As a result of numerical analysis , the groove height required to obtain maximum tracking sensitivity and the optimum film thickness of multilayers are found. It is important to optimi ze the groove height for the cancellation of crosstalk.