Design and Optimization of Encoded and Tunable Graphene-Silver Metasurface Surface Plasmon Resonance Sensor for Detection of Low Refractive Index Variation in Terahertz Regime

This study presents a highly sensitive sensor designed for the detection of low refractive index substances in the THz range. The sensor leverages a hybrid metasurface combined of graphene and silver nanostructures, taking advantage of the extraordinary optical properties of graphene and the plasmonic resonances of silver. By carefully engineering the geometric parameters of the sensor and optimizing the synergistic interactions between the graphene and plasmonic components, the proposed sensor achieves a sensitivity of 300 GHzRIU⁻¹, a figure of merit of 1.351 RIU⁻¹, and a detection limit of 0.608 RIU for refractive indices ranging from 1.34 to 1.39. The design features three resonator structures—Small Circular Resonator Design (SCRD), Square Split Ring Resonator Design (SSR), and Large Circular Resonator Design (LCRD)—strategically integrated to enhance performance. Additionally, the sensor demonstrates encoding capabilities, modelling a NOR gate with high transmittance efficiency. These results highlight the sensor’s potential for multifunctional applications in various fields like biomedical and environmental.