Ambient-energy-driven space-time-coding metasurface for space-frequency-division multiplexing wireless communications

Programmable metasurfaces have shown exceptional potentials in wireless communications due to their capability to manipulate electromagnetic (EM) waves dynamically and flexibly. However, the large-scale application and flexible deployment of programmable metasurfaces still face challenges of high communication capacity requirements and stringent energy constraints. Here, we report an ambient-energy-driven space-time-coding metasurface to address these issues. On one hand, the metasurface can achieve efficient space-frequency-division multiplexing manipulations by dynamically controlling multiple frequencies and the spatial propagation directions of reflection EM waves. On the other hand, the shared-aperture ambient solar energy harvesting capability and low power consumption characteristic of the metasurface enable it to be self-powered without relying on any external power supply. To demonstrate these remarkable features, a four-channel wireless communication system prototype is built using the programmable metasurface. Experimental results confirm that four distinct images can be transmitted to four user terminals simultaneously, independently, and in real time with remarkably low energy consumption per bit. Such innovative metasurface provides a simple and effective approach for integrating ambient energy harvesting, multi-dimensional microwave manipulation, and direct information modulation on a single physical platform, which will advance the wireless communications in cost-effectiveness, enhanced capacity, energy efficiency, and environmental friendliness.