Multiple Spoof Plasmonically Induced Transparency for Sensing Applications

Abstract

We design a pair of resonators to realize multiple spoof plasmonically induced transparency (PIT) with high-Q group delays, which show potential in sensing applications. To reveal the mechanism of the multiple spoof PIT scheme, we deduce mathematical equations of a simplified model composed of multiple harmonic oscillators, and we further propose an equivalent-circuit model to analyze the metamaterials in an intuitive way. A prototype consisting of a broadband stub resonator and a spoof localized surface-plasmonic resonator is further fabricated to detect the complex permittivity of high-lossy liquids and solid samples in microwave bands. Experimental results show that the group-delay-based sensor can work well even when high-order modes are weakly excited, and the trade-off between sensitivity and properties of samples is discussed. The proposed double-resonator scheme with multiple spoof PIT is universal, and we design a metasurface working in terahertz bands to show that the concept can be widely used in various surface-sensing applications.