Unconditionally stable nearly PML algorithm for linear dispersive media

Unconditional stable alternating direction implicit (ADI) formulations of the nearly perfectly matched layer (NPML) are presented for truncating linear dispersive finite difference time domain (FDTD) grids. The digital signal processing (DSP) algorithms developed for digital filters are used to implement the frequency dependent property of the media into the ADI-FDTD algorithm. The formulations have the advantage of simplicity of ADI-FDTD implementation. Numerical examples carried out for linear Debye and Lorentz dispersive domains are included to validate the proposed formulations.