Closed-form expression of numerical reflection coefficient at PML interfaces and optimization of PML performance

The authors present a derivation of the closed-form expression of numerical reflection at interfaces of perfectly matched layer (PML). Reflection coefficients at single interfaces and of finite-thickness absorbers are presented. The derived closed-form expression is found to match identically With the reflection coefficient obtained directly through finite-difference time-domain computation. The closed-form expression of numerical reflection coefficient can significantly facilitate the optimization of PML performance.