Numerical research on supercavity sensing driven by guided resonance in a terahertz all-metal metamaterial absorber

Abstract

Terahertz metamaterial sensing features high sensitivity and rich fingerprint spectrum, which shows an application potential of the great significance. However, limited by low-quality resonances and insufficient sensitivity, the sensing performance of terahertz metamaterials remains at a moderate level. In this paper, we numerical investigate a high-performance terahertz sensor based on plasmonic supercavity sensing. The proposed metamaterial sensor features an adjustable high quality absorption resonance ascribed to guided resonance excited by band-folding effect. Also, the terahertz plasmonic sensor inherently characterizes a high sensitivity owing to the all-metal design, which can limit the resonant field within the structured metal surface to fully couple with analyte. Based on these advantages, the proposed all-metal sensor demonstrates the maximum resonance frequency shift, sensitivity and sensing figure of merit are about 66%, 1.6 THz/RIU and 218, respectively, substantiating the sensing superiority. The proposed metamaterial absorber shows potential in spectroscopy, in addition to being a multifunctional absorber and sensor.