Efficient FDTD Implementations of the Higher-Order PML Using DSP Techniques for Arbitrary Media

Efficient and unsplit-field implementations of the higher-order PML based on the digital signal processing (DSP) techniques and the complex frequency shifted perfectly matched layer (CFS-PML) formulations are proposed to truncate the finite-difference time-domain (FDTD) computational domains. The CFS-PML implementation is introduced based on the stretched coordinate PML (SC-PML) and the uniaxial anisotropic PML (UPML), respectively. These formulations are completely independent of the material properties of the FDTD computational domain and hence can be applied to truncate arbitrary media without any modification. Moreover, the higher-order PML has the advantages of both the conventional PML and the CFS-PML in terms of absorbing performances. Three numerical simulations have been carried out in three dimensional (3-D) FDTD computational domains to validate these formulations. It is shown in the numerical simulations that the proposed PML formulations with the higher-order scheme are effective in terms of attenuating both the low-frequency propagating waves and evanescent waves and reducing late-time reflections, and also hold comparatively good absorbing performances as compared with the conventional SC-PML and the convolution PML (CPML) with the CFS scheme.