Single-Layer Ultra-Wideband Multifunctional Transmissive Metasurface

The metasurface is a functional film device based on a subwavelength structure, which has a strong light field control ability and has the advantages of ultrathin, low loss, and easy manufacturing. However, realizing a multifunctional metasurface, yet simple enough to design, manufacture, and thin is still a challenge. In this article, we propose a novel metasurface with negligible thickness as a beam splitter, which can achieve half transmission and half reflection of the incident wave at the same frequency. It also controls the polarization of circularly polarized electromagnetic (EM) waves in the transmission mode. A broadband operation can be achieved based on the geometric phase theory, and the phase control can be achieved by azimuth rotation of the structure. The numerical results of the metasurface are in good agreement with the experimental results in the measured frequency range. The ultrathin multifunctional metasurface realized by the geometric phase principle provides an important stepping stone for simple optical devices and can be extended to a higher frequency range.