Metasurface with Directional‐Controlled Asymmetric Transmissions

The diverse design freedom and exotic electromagnetic properties of metasurfaces enable them to achieve unprecedented capability and superiority with regard to conventional optical elements. Herein, a bifunctional microwave metasurface with an asymmetric bidirection transmission phase that can be controlled is reported. The proposed metasurface is composed of bilayered double‐arrow‐shaped structures sandwiching a subwavelength metal grating. Such design can achieve not only linear polarization (LP) conversion for two oppositely directed wave incidences but also phase control independently by introducing a rotation and adjusting the geometrical parameters of the double‐arrow‐shaped structures. The metasurface breaks the symmetry and realizes different functions for opposite propagation directions, such as deflection and focusing, orbital angular momentum (OAM) mode generation, and holographic imaging. The experimental results suggest that the proposed Janus metasurface can be further exploited as an attractive platform for various applications ranging from microwave reconfigurable beam antenna and multifunctional polarization control to optical imaging, sensing, and information processing.