Terahertz refractive index sensor based on triple-band absorption metasurface

Abstract

High-performance metasurface refractive index sensors are extremely promising for biosensing, petroleum, agricultural production, and security detection fields. We theoretically propose a terahertz refractive index sensor based on absorption mechanism, which can achieve an excellent triple-band absorber and high-performance refractive index sensor. The proposed triple-band absorber may achieve 90.22%, 98.87%, and 99.91% at 0.93, 1.12 and 1.45 THz, respectively. Multi-band response promises multi-point matching of the resonant frequency between the sensor and the measured substance, thus enabling a high-accuracy terahertz sensor. The refractive index sensor has the maximum sensitivity (S), quality factor (Q), and figure of merit (FOM) of 420 GHz/RIU, 71.54, and 21.4 RIU⁻¹, respectively. The triple-band absorber is achieved by the combination of electric and magnetic dipole responses and the sensing performance is determined by localized electromagnetic field distribution. The proposed terahertz refractive index metasurface sensor has a promising application prospect in biosensing and critical parameter measurement for oil and gas wells.