An absorbing boundary condition for the fourth order FDTD scheme

An alternative stable approach that is of the fourth order and that allows one to shrink the computational domain through a scatterer is presented. This method is an application of the generalized image principle to Maxwell´s equations. The method consists of adding an absorbing term to the usual equation of propagation. The image theory applied to the fourth-order Maxwell-FDTD (finite-difference time-domain) algorithm is shown to lead to a heavier formulation than for a regular boundary condition of the same order used with an interface between the 4*4 inner domain scheme and the 2*2 boundary scheme. Despite this heaviness, the image theory method seems to be a good tool, because it makes it possible to shrink the computational domain within a heterogeneous scattering sequence to be studied.<>