Electromagnetically Induced Transparency-Like Approach Based on Terahertz Metamaterials for Ultrasensitive Refractive Index Sensors

In this paper, we design a sensor based on the electromagnetically induced transparency-like (EIT-like) approach in the terahertz range in order to realize a terahertz metamaterial device with an enhanced combination of ${Q}$ value and sensitivity. The Lorentz harmonic oscillator model and the asymmetry parameter are used for analyzing its internal physical mechanism. After processing the designed structure and performing experimental verification, a good consistency between the experiment and theoretical framework is found in terms of the position and strength of the resonance peak. Subsequently, glucose tablets of different concentrations are fabricated in order to verify the practical application of the designed sensor for distinguishing the presence of tablets with different concentrations. Finally, it is found through model optimization and sensor performance evaluation that our prototype exhibits a sensitivity value of about 330 GHz/RIU, a quality factor ${Q}$ of 24, while a recorded transparency peak above 80% is obtained. Therefore, as the metamaterial refractive index sensor presents an enhanced performance, it possesses great perspectives for various practical applications including the potential detection of different pharmaceuticals or biochemical products as well as the identification of various concentrations of the same sample.