Enhancing the PML absorbing boundary conditions for the wave equation

The dynamics of wave propagation and interactions in general media is described either by the system of Maxwell's equations, or by the wave equation. This paper focuses on problems modeled by the scalar wave equation, with one or more boundaries at infinity. The computational domain is truncated by a perfectly matched layer (PML) absorbing boundary condition (ABC) modified specifically for wave-equation applications. A problem independent approach is used to enhance the PML performance within the whole frequency band of excitation, in the presence of both evanescent and propagating fields. Numerical reflections below 0.1% are achieved with PML thickness of only six to eight cells, in both open and guided-wave problems. Index Terms--Absorbing boundary conditions (ABC), finite-difference time-domain (FDTD) methods, perfectly matched layer (PML), wave equation.