Full‐Space Janus Meta‐Lens for Shared‐Aperture Transmission‐Reflection‐Independent Focusing of Electromagnetic Wave

Janus metasurfaces emerge as a promising platform for implementing multiple wave functionalities by fully exploiting the inherent propagation direction of electromagnetic waves. Their out‐of‐plane asymmetric structures enable different wave functions depending on the propagation direction. Herein, a multiplexed Janus metasurface is proposed, which operates in the microwave region to flexibly manipulate the transmission and reflection wavefronts for same linearly polarized (LP) incidence propagating along the two opposite directions. A meta‐lens is constructed to validate the concept of full‐space shared‐aperture transmission‐reflection‐independent focusing of electromagnetic (EM) waves, exhibiting four distinct focusing performances. Experiments are conducted in the microwave region that agree well with the simulation results. The proposed full‐space Janus metasurface may provide a platform for asymmetric imaging, multichannel information processing, and encrypted communication.