Analysis method for light scattering from magnetic materials by the three-dimensional boundary element method

To analyze the light scattered from a magneto-optical disk, a method is proposed for calculating the light scattered from a magnetic material with grooves. The model used is divided by an infinite boundary between the free space or an isotropic dielectric and an isotropic magnetic material. By using the relative permittivity of the isotropic magnetic material, the governing equation for the magnetic material is derived from Maxwell's equations. The three-dimensional boundary element method is applied to this equation. The boundary element equation for free space or an isotropic dielectric material is the one in which the boundary element method is applied to a general Helmholtz equation. The one in the magnetic material is obtained by adding the volume integral in the magnetic material to the general equation. If boundary elements are large, the integral in the magnetic material near the boundary is evaluated at too small a value. The numerical results oscillate with only the foregoing method. To resolve this problem with taking practical memory size and computation time into consideration, an attenuating term is added to Green's function used in the integration in the magnetic material. With the method proposed, the optical scattering from a magnetic material can now be analyzed.