High-efficiency Huygens' metasurface for terahertz wave manipulation.

A fair amount of theoretical work has shown that Huygens' metasurfaces well modulate electromagnetic waves by properly designing electrical impedance Z and magnetic admittance Y; however, the transmissive Huygens' metasurface is still challenging in the terahertz band. In this work, a transmission-type Huygens' metasurface with bilayer metallic patches has been proposed and theoretically demonstrated to show a reflectionless phase modulation for a linearly polarized terahertz wave. The simulation results show that the metasurface can achieve 2π phase coverage, and importantly the phase change can be simply achieved by changing a single geometric parameter of the metamolecule, along with a similar transmission effect. We design a high-efficiency beam deflector to realize an anomalous refraction with an angle of 19.8°. The proposed metasurface will provide a simple and direct way to realize efficient terahertz devices for wavefront manipulation.