CPML: An Efficient FDTD Implementation of the CFS-PML for Arbitrary Media Not for Distribution Submitted to Microwave and Optical Technology Letters, June 2000 1 Convolutional PML (CPML): An Efficient FDTD Implementation of the CFS-PML for Arbitrary Media J. Alan Roden Personal Systems Group IBM Corporation Research Triangle Park, NC 27709 Email: jaroden@us.ibm.com FAX: 919-543-8221 and Stephen D. Gedney Department of Electrical and Computer Engineering University of Kentucky Lexington, KY 40506-0046 Email: gedney@engr.uky.edu FAX: 859-257-3092 Key Terms: finite-difference time-domain (FDTD), perfectly matched layer (PML), stretched coordinates Abstract A novel implementation of perfectly matched layer (PML) media is presented for the termination of FDTD lattices. The implementation is based on the stretched coordinate form of the PML, a recursive convolution and the use of complex frequency shifted (CFS) PML parameters. The method, referred to here as the convolutional PML (CPML) offers a number of advantages over the traditional implementations of the PML. Specifically, the application of the CPML is completely independent of the host medium. Thus, no modifications are necessary when applying it to inhomogeneous, lossy, anisotropic, dispersive or non-linear media. Secondly, it is shown that the CFS-PML is highly absorptive of evanescent modes and can provide significant memory savings when computing the wave interaction of elongated structures, sharp corners, or low frequency excitations.