Fabry-P\'erot Huygens' Metasurfaces: On Homogenization of Electrically Thick Composites

TL;DR

This paper introduces a practical design method for Fabry-Pérot Huygens' metasurfaces that simplifies the realization of anomalous refraction effects in TM propagation by using homogenization theory and Floquet-Bloch analysis, reducing reliance on complex simulations.

Contribution

It presents a homogenization-based design approach for electrically thick Fabry-Pérot metasurfaces that mimic zero-thickness metasurfaces, verified through analytical and full-wave simulation methods.

Findings

The Floquet-Bloch analysis accurately predicts scattered fields for arbitrary angles.

The proposed design method aligns well with full-wave simulation results.

Homogenization theory applies effectively to thick metasurface structures.

Abstract

Realization of the anomalous refraction effects predicted by Huygens' metasurfaces (HMS) have required tedious and time-consuming trial-and-error numerical full-wave computations. It is shown herein that these requirements can be alleviated for transverse magnetic (TM) propagation by a periodic dielectric-based HMS consisting of an electrically thick array of cascaded Fabry-P\'erot etalons. This "Fabry-P\'erot HMS" (FP-HMS) is easily designed to mimic the local scattering coefficients of a standard zero-thickness HMS (ZT-HMS) which, according to homogenization theory, should result in the desired anomalous refraction. To probe the characteristics of this practical FP-HMS, a method based on Floquet-Bloch (FB) analysis is derived for predicting the fields scattered from it for arbitrary angles of incidence. This method produces simple closed-form solutions for the FB wave amplitudes and the resulting fields are shown to agree well with full-wave simulations. These predictions and full-wave simulations verify the applicability of homogenization and scattering properties of zero-thickness HMS's to thick structures. They also verify the proposed semi-analytical microscopic design procedure for such structures, offering an effective alternative path to implementation of theoretically envisioned intricate field manipulating devices.