Examination of Perfectly Matched Layer Performance for Evanescent Waves

Performance of perfectly matched layer (PML) for evanescent plane waves is examined. According to the model of guidance based on total internal reflection, evanescent waves exists outside the core of the waveguide. In this article the situations where PML can yield significant errors are presented. The results obtained for a simple planar structure can be generalized for analyses of arbitrary open waveguides where the computational domain is terminated by the perfectly matched layer.