Uniform Ray Description of Physical Optics Scattering by Finite Locally
Periodic Metasurfaces
Abstract
This paper presents a uniform ray description of electromagnetic wave
scattering by locally periodic metasurfaces of polygonal shape. The
model is derived by asymptotically evaluating the critical-point
contributions of a physical optics scattering integral. It is valid for
metasurfaces whose bulk scattering coefficients are periodic functions
of a phase parameter which, in turn, is a continuous and smooth function
of surface coordinates. The scattered field is expressed in terms of
reflected, transmitted and diffracted rays that do not generally obey
conventional geometrical constraints (i.e., Snell’s law and the Keller
cone). An iterative technique is presented to determine the locations of
critical points on one or multiple interacting metasurfaces. Numerical
results demonstrating the utility and accuracy of the asymptotic
physical optics model are also provided.