Numerical reflection from FDTD-PMLs: a comparison of the split PML with the unsplit and CFS PMLs

Although perfectly matched layer (PML) absorbing boundary conditions are perfect in theory, an amount of spurious reflection is present in actual computations with the finite-difference time-domain (FDTD) method. This paper compares the reflections produced by three different PMLs, namely the split PML, the unsplit PML, and the recently introduced complex frequency shifted (CFS) PML. It is shown that the reflections from the split and unsplit PMLs are identical, while the CFS PML allows the reflection of evanescent waves to be significantly reduced