Time-Synchronised Convolutional Perfectly Matched Layer for Improved Absorbing Performance in FDTD

A performance enhancing modification to the convolutional perfectly matched layer (CPML) technique for implementing the complex frequency shifted perfectly matched layer (CFS-PML) absorbing boundary condition is presented. By adopting this modification an apparent discrepancy in the time synchronisation between the CPML and the main FDTD algorithm is resolved. This is achieved by employing a semiimplicit approach which synchronises CPML with the main FDTD algorithm. It is shown through 2D and 3D numerical examples, that the suggested modification to the CPML algorithm increases its performance without increasing its computational cost.