Intelligent Metasurfaces with Continuously Tunable Local Surface Impedance for Multiple Reconfigurable Functions

How might one make metasurfaces ``intelligent'', to offer multiple reconfigurable functions? The authors show that it can be done by embedding individually addressable tunable chips (mixed-signal integrated circuits) in each unit cell. This enables independent, continuous control of both the resistive and reactive parts of the local complex surface impedance. This allows a broader range of functionalities, among which tunable arbitrary-angle perfect absorption and tunable perfect anomalous reflection are showcased in this study. Further development could unlock other tunable functionalities, such as arbitrary wave-front shaping, space-time-modulated devices, holography, and sensing.