Choice of the perfectly matched layer boundary condition for frequency-domain Maxwell’s equations solvers

We show that the performance of frequency-domain solvers of Maxwell’s equations is greatly affected by the kind of the perfectly matched layer (PML) used. In particular, we demonstrate that using the stretched-coordinate PML (SC-PML) results in significantly faster convergence speed than using the uniaxial PML (UPML). Such a difference in convergence behavior is explained by an analysis of the condition number of the coefficient matrices. Additionally, we develop a diagonal preconditioning scheme that significantly improves solver performance when UPML is used.