Programmable Manipulations of Terahertz Beams by Transmissive Digital Coding Metasurfaces Based on Liquid Crystals

Abstract

AbstractDigital coding metasurfaces have attracted considerable interest, owing to their ability to manipulate electromagnetic waves and implement various functionalities with programmable controls. These metasurfaces offer high‐resolution and high‐speed responses; thus, they are implemented in high‐speed imaging, nondestructive sensing, and wireless communication. However, traditional active metasurfaces are typically based on semiconductor components, which are difficult to realize at terahertz frequencies. Additionally, non‐magnetic transmissive metasurfaces cannot realize a large phase‐tuning range without increasing the number of metasurface layers. Herein, a 1‐bit transmissive digital coding metasurface based on liquid crystals is proposed to achieve programmable terahertz beam manipulations with electric control. The Fano resonance that is excited in the asymmetrical metasurface element enables a larger phase variation while maintaining the transmittance. The proposed digital metasurface can effectively achieve many functionalities, such as dual beam steering, multiple beams, and orbital angular momentum beams, via altered coding patterns; an example of dual beam steering is experimentally verified. This study is expected to provide a promising method to manipulate transmissive terahertz beams using a digitally programmable metasurface, and it has potential applications in imaging, sensing, and wireless communications.