Analysis of the Radial PML in Cylindrical Finite Integration Technique Using a Hybrid Implicit-Explicit Update Scheme

We study the performance of the Perfectly Matched Layer (PML) boundary technique within a Finite Integration/Finite Differences method for the simulation of electromagnetic waves in structures with rotational symmetry. To solve the stability issues of PML in time-domain which have been reported in literature, we have previously introduced a hybrid implicit-explicit algorithm. It applies a stabilizing implicit update scheme for components within the PML region only, but reduces to the standard explicit leapfrog method in the main computational domain. For a so-called 2.5-D grid in ρz-coordinates, this algorithm is extended to the PML in the ρ-direction, and its stability and accuracy properties are analyzed. The results show that the radial ρ-PML has less influence on the stability of the time integration compared to the longitudinal z-PML. Thus, it can be operated using the same parameters as longitudinal PML or even using standard leapfrog integration.