On the development of a higher-order PML

A higher-order perfectly matched layer (PML) is proposed based on stretched coordinates to effectively attenuate both propagating and evanescent waves. The new PML has multiple poles in contrast to the regular PML with a single pole. The implementation is also derived and results are shown to be better than those of the regular PML and the recently proposed complex-frequency shifted (CFS) PML with an insignificant increase in the computational cost.