An anisotropic PML absorbing media for the FDTD simulation of fields in lossy and dispersive media

A uniaxial anisotropic perfectly matched layer (PML) absorbing material is presented for the truncation of finite-difference time-domain (FDTD) lattices for the simulation of electromagnetic fields in lossy and dispersive material media. It is shown that by properly choosing the constitutive parameters of the uniaxial media both propagating and evanescent waves can be highly attenuated within the PML medium. This resolves the concern that the original Berenger's formulation for a PML medium does not attenuate evanescent waves. FDTD formulations for the uniaxial PML method are presented for lossy and dispersive medium. Based on this formulation an equivalent modified representation of Berenger's split equations is also derived. Through numerical examples, it is demonstrated that the uniaxial PML method provides a nearly reflectionless absorbing boundary for the FDTD simulation of evanescent and propagating waves encountered in highly dispersive and lossy medium.