Retrieving effective surface susceptibilities of high-index metasurfaces based on dipole approximation

Abstract

Electromagnetic (EM) characterization of metamaterials and metasurfaces is crucial for theoretical modeling and also efficient design of state-of-the-art applications. Thus far, the widely used parameter retrieval methods have been provided unphysical artifacts in modeling of metasurfaces. In this work, we develop a new parameter retrieval method which is based on dipole approximation and Ewald lattice summation. This technique can be used to efficiently characterize metasurfaces that support simultaneous electric and magnetic dipole resonances, when illuminated by a plane-wave at an arbitrary angle of incidence. We retrieve the effective parameters of a high-index metasurface composed of silicon nanospheres and demonstrate that in contrast to the conventional methods, the proposed model successfully describes its optical responses. Based on our results, it is demonstrated that even in metasurfaces composed of isotropic structures, bianisotropic terms can be excited at oblique angles of incidence. The developed parameter retrieval method is much more efficient compared to conventional methods, and it is certainly useful in precise modeling and proper designing of even more complex optical metasurfaces.