Ultrathin Single-Substrate Pancharatnam–Berry Phase Metasurface With High Transmission Efficiency

The Pancharatnam-Berry (PB) phase or geometricphase metasurfaces have been extensively investigated in orderto achieve flexible manipulation of circularly polarized (CP)electromagnetic waves. Typically, the thickness or structuralcomplexity of the transmission-type PB metasurfaces may limittheir efficiency. Here, we propose a single-substrate, ultrathin,transmission-type PB phase metasurface with a transmissioncoefficient of approximately unity for CP waves. To achieve this,the Huygens principle is applied in the design. The proposedmetasurface is capable of achieving high-efficiency transmis-sion amplitude of two orthogonal linear polarizations in theworking frequency band, as well as the 180 degrees phase difference.Thus, high-efficiency CP transmission with nearly unity canbe obtained, and 360(degrees)of phase modulation can be covered byrotating the element. Meanwhile, the proposed metasurface is asingle-substrate structure and its thickness is only 0.06 lambda(0), offeringa simple yet efficient method for antenna design. As a proof ofconcept, a metalens antenna and an orbital angular momentum(OAM) wave generator based on the proposed metasurfaceare experimentally demonstrated. The measured results showgood agreements with the full-wave simulations, successfullyverifying the design theory. The proposed metasurface offers analternative platform for designing high-performance devices withthe advantages of lightweight, low cost, and simple fabrication