Full-space programmable circularly polarized metasurface for space-multiplexing wireless communications

The programmable metasurface has been proved to be an effective tool to dynamically tailor electromagnetic (EM) waves. However, how to achieve real-time and independent controls of circularly polarized (CP) waves in the transmission and reflection spaces is still a challenge. To address this problem, we propose a full-space programmable CP metasurface, which can independently manipulate the CP waves in transmission and reflection spaces in real time by controlling the bias voltage. The polarization states of reflected and transmitted CP waves can be independently customized through elaborate meta-atom design. As a proof of concept, we designed, fabricated, and measured a full-space programmable CP metasurface that can realize copolarized reflection for right-handed circularly polarized (RCP) waves and cross-polarized transmission for left-handed circularly polarized (LCP) waves. Simulated and measured results verify that the wavefronts of reflected and transmitted CP waves can be independently manipulated in real time by reprogramming the reflection and transmission phase coding sequences. Based on the full-space programmable CP metasurface, a space-multiplexing wireless communication scheme is established, successfully delivering two different images along preset reflection and transmission channels.