Fabry-pérot bianisotropic metasurfaces for perfect anomalous refraction

It has been shown that an easily designed array of Fabry-Pérot etalons can emulate the scattering capability of a theoretical zero-thickness Huygens' metasurface [1]. Each etalon of this 'Fabry-Pérot Huygens' Metasurface' (FP-HMS) consists of a parallel plate waveguide filled with two symmetric dielectric layers [Figure 1(a)] to control the transmission and reflection coefficients through it. These coefficients are those obtained for the equivalent zero-thickness structure abstractly characterized by a periodic surface electric impedance Z {se} and surface magnetic admittance Y {sm} [2]. An FP-HMS analytically designed (without resort to full-wave solvers) to alter the direction of a plane wave passing through it [Figure 1(b)] was shown both analytically and numerically (CST) to produce this desired anomalous refraction [1], and to provide results fully consistent with the ideal zero-thickness Huygens' metasurface [2]. However, the designed scattering necessarily included reflected components [see interference pattern in Figure 1(c)], so that a portion of the incident energy was lost to spurious scattering.