Unconditionally stable ADI-FDTD implementation of PML for frequency dispersive Debye media

An efficient, unsplit-field and unconditional stable formulations of the perfectly matched layer (PML) are presented for truncating frequency dispersive first-order Debye media. The formulations are based on the alternating direction implicit finite difference time domain method and the auxiliary differential equation PML approach. A one-dimensional numerical example is included to validate the proposed formulations.