Bipartite Dielectric Huygens' Metasurface for Anomalous Refraction

Abstract: Huygens' metasurfaces - fundamentally based on Schelkunoff's equivalence principle, Huygens' metasurfaces consist of a two-dimensional array of Huygens' sources formed by co-located orthogonal electric and magnetic dipoles. Such metasurfaces provide electric and magnetic responses to an incoming electromagnetic (EM) wave, leading to unidirectional scattering and 2$\pi$ phase coverage. We herein report a near-reflectionless coarsely discretized dielectric Huygens' metasurface that performs anomalous refraction, offering a low-loss platform for wave manipulation at high frequencies as compared to their lossy metallic analogue. The coarse discretization dramatically simplifies the design, resulting in a metasurface that is highly efficient, cost-effective, and robust. In this paper, the proposed metasurface comprises two meta-atoms per period and is hence named the bipartite dielectric Huygens' metasurface. Through full-wave simulations at 28 GHz, we show that the proposed metasurface can reroute an incident EM wave from $\theta_i=15^{\circ}$ to $\theta_t=-44.5^{\circ}$ with very high efficiency: 87% of the scattered power is anomalously transmitted to $\theta_t$. Based on our observations, a coarsely discretized dielectric Huygens' metasurface platform can be efficacious to design meta-devices with multifaceted functionalities in different frequency regimes.