摘要： An unconditionally stable implementation of the higher order complex frequency-shifted perfectly matched layer (CFS-PML) based on the Crank–Nicolson-approximate-decoupling (CNAD) algorithm and the bilinear transform (BT) method is proposed to terminate the finite-difference time-domain (FDTD) lattice. The proposed scheme not only takes advantage of the CNAD algorithm in terms of reducing computational time but also has the advantage of the conventional FDTD algorithm in terms of absorbing performance. Two numerical examples are provided to validate the proposed implementation in the homogenous free space and lossy FDTD domains. The results show that the proposed scheme can overcome the Courant–Friedrich–Levy condition compared with the conventional FDTD method and further enhance the absorbing performance compared with the first order PML implementation.