A Self-Adaptive Reconfigurable Metasurface for Electromagnetic Wave Sensing and Dynamic Reflection Control.

In the past decade, reconfigurable metasurfaces have attracted significant attention. While existing reconfigurable metasurfaces require human intervention to switch functionalities, feature non-electromagnetic detection modalities or involve time-consuming and resource-intensive deep learning processes, in this work a simple real-time self-adaptive metasurface is reported that senses the direction of arrival of an incident wave, and adjusts its reflection accordingly. This proposed metasurface integrates sensing and reconfigurable reflection meta-atoms using a simple phase comparator and a lookup table. This eliminates auxiliary detection modalities and external controller units, achieving dramatic savings in response time, energy consumption and fabrication cost. As examples, we design and investigated metasurfaces which self-adaptively redirect or focus an incoming wave from any direction to a desired direction or location. It is experimentally demonstrated that the self-adaptive metasurface can reflect the incoming wave from any direction within ±50° to the normal reflection direction with great efficacy. Further, the metasurface self-adapts quickly, properly redirecting waves whose incidence angle changes by up to 12 deg/s with power consumption as low as 415 mW. Such metasurfaces provide an autonomous, computationally simple, cost-effective, energy efficient and real-time solution for a self-adaptive reflection control, and open exciting possibilities for wireless communication, radar sensing and related applications.