A review of light‐controlled programmable metasurfaces for remote microwave control and hybrid signal processing

Abstract Programmable metamaterials and metasurfaces have gained great interest due to real‐time electromagnetic control and digital information processing capabilities. Different from traditional electrically‐controlled programmable metasurfaces, recently, light‐controlled programmable metasurfaces have been presented, on which the microwaves can be manipulated and modulated wirelessly in the space domain or time domain by incident light. More importantly, such the metasurface platform offers an efficient interface to link directly light and microwave signals, showing huge potential to develop wave‐based optoelectronic hybrid devices and relevant applications. Here, we review some of these recent developments, focusing particularly on the mechanisms of light‐controlled programmable metasurfaces and their fascinating functions from remote microwave control to hybrid signal processing. We survey related implementation methods based on the hybrid integrations of microwave digital metasurfaces and different photoresponsive components including photodiodes, photoresistors, infrared modules, and light sensors, as well as discuss their unique advantages. In the summary, the perspective on the challenges and future directions of light‐controlled programmable metasurfaces are presented.