Advanced Terahertz Refractive Sensing And Fingerprint Recognition Through Metasurface‐Excited Surface Waves

Abstract High‐sensitive metasurface‐based sensors are essential for effective substance detection and insightful bio‐interaction studies, which compress light in subwavelength volumes to enhance light–matter interactions. However, current methods to improve sensing performance always focus on optimizing near‐field response of individual meta‐atom, and fingerprint recognition for bio‐substances necessitates several pixelated metasurfaces to establish a quasi‐continuous spectrum. Here, a novel sensing strategy is proposed to achieve Terahertz (THz) refractive sensing, and fingerprint recognition based on surface waves (SWs). Leveraging the long‐range transmission, strong confinement, and interface sensitivity of SWs, a metasurface‐supporting SWs excitation and propagation is experimentally verified to achieve sensing integrations. Through wide‐band information collection of SWs, the proposed sensor not only facilitates refractive sensing up to 215.5°/RIU, but also enables the simultaneous resolution of multiple fingerprint information within a continuous spectrum. By covering 5 µm thickness of polyimide, quartz and silicon nitride layers, the maximum phase change of 91.1°, 101.8°, and 126.4° is experimentally obtained within THz band, respectively. Thus, this strategy broadens the research scope of metasurface‐excited SWs and introduces a novel paradigm for ultrasensitive sensing functions.