Source decomposition as a global absorbing boundary condition for multi-region problems

A two dimensional implementation of the source decomposition method (SDM) is presented in comparison with the PML and Higdon absorbing boundary conditions for FDTD applications. The SDM is global in nature, however it can accommodate reflective external domains. The comparison shows that the results are of similar quality, indicating that the Higdon conditions can be a viable choice at a lower cost as far as non-reflective boundaries are concerned. The SDM is grid compatible and can be integrated into a general diakoptic scheme. It is expected to perform best over smooth boundaries, since corners tend to generate instabilities at the moment.