A simple and efficient implementation of CFS-PML in the FDTD analysis of periodic structures

The use of perfectly matched layers (PMLs) is one of the most popular techniques employed for mesh truncation in finite-difference time-domain (FDTD) simulations. Its original form, however, has a poor absorption of evanescent waves, which are highly present in simulations of periodic structures. A better absorption has been achieved using a complex frequency shifted (CFS) PML, which has been implemented via a convolution scheme. In this letter, we present a simple and efficient implementation of the CFS PML and apply it to periodic structures.