An efficient FDTD implementation of the PML with CFS in general media

Perfectly matched layer (PML) absorbing media has proven to be the most robust and efficient technique for the termination of FDTD lattices. Unfortunately, the PML can still suffer from late time reflections when terminating highly elongated lattices or when simulating fields with very long time signatures. This is partly due to the weakly causal nature of the PML. Alternatively, a strictly causal PML was introduced in Kuzuoglu and Mittra (1996). The resulting tensor is referred to here as the complex frequency shifted (CFS) tensor. The application of this technique within the FDTD has been presented previously. Here, the formulation is postulated for a generalized medium, including lossy, dispersive, anisotropic, or non-linear media. For such a medium, there are no additional memory requirements as compared to the standard FDTD/PML methods. Furthermore, it is demonstrated that it accurately absorbs highly oblique incident waves with long time signatures and is computationally efficient.