Terahertz Perfect Metasurface Absorber Based on Groove-Ring-Shaped Ti3C2Tx MXene for Refractive Index Sensing Application

In this paper, we present a novel design of a perfect metasurface absorber (MSA) based on groove-ring-shaped (GRS) structure Ti₃C₂T_x MXene array, which demonstrates a significant potential of for enhanced refractive index (RI) sensing application in terahertz (THz) region. In contrast to the conventional metal-dielectric-metal (MDM) structures, the proposed design incorporates a lightweight material and eliminates the need for a sandwich configuration. Consequently, this innovation significantly simplifies the production process and reduces costs, which facilitates its application in industrial production. Numerical simulation reveals that the proposed MSA operates at 1.938 THz with a near-perfect absorbance of 99.93%, aligning closely with predictions from coupling mode theory (CMT) and equivalent circuit model (ECM). The perfect absorption exhibited by the designed structure is primarily attributed to the guided mode arising from critical resonance coupling. Furthermore, the geometric parameter tuning mechanism of the proposed MSA allows for precise and dynamic adjustments of both peak absorption frequency and absorptivity. This approach aims to establish an RI sensing platform characterized by high sensitivity, rapid response, and excellent stability. Our innovative MSA excels as an RI sensor, showcasing an impressive sensitivity of 1.79 THz/RIU. These findings pave the way for the development of highly efficient MSAs, which hold significant potential for applications in spectral imaging, thermal radiation absorption, and sensing technology within the THz frequency range.