Multi-Domain Manipulations of Multi-Frequency Waves Based on Asynchronous Space-Time-Coding Digital Metasurface

Abstract

Metasurfaces have garnered significant attention for the ability to manipulate electromagnetic (EM) waves, enabling diverse applications such as beam steering, frequency conversion, and vortex-wave generation. However, achieving complete control of the EM properties such as phase, amplitude, polarization and momentum over multiple frequencies remains a challenge. Here, an asynchronous space-time-coding digital metasurface (ASTCM) is proposed to tackle the challenge. By segmenting the metasurface into distinct partitions and letting them be modulated at different frequencies and operated with different functions, ASTCM facilitates precise and comprehensive manipulations of multi-frequency EM waves, eliminating the need for multiple oscillators and radio-frequency (RF) chains. As proof-of-concept examples, three ASTCM experiments are carried out, including multi-frequency beam steering, construction of wireless communication system, and direction-of-arrival estimation. These experiments concurrently demonstrate the capability of ASTCM in manipulating full EM properties on multifrequency waves in a simple way, showcasing its potential to revolutionize wireless communication, radar, and integrated communication and sensing systems.