提出了一种以双开口谐振环和金属短线组合结构为基本单元的太赫兹高灵敏度传感器。具有不同辐射损耗的谐振环和金属短线的电磁波在远场的相消性干涉,使得反射谐振的线宽压窄,呈现出典型的非对称Fano型反射谱。数值模拟表明:通过改变双开口谐振环与金属短线之间的耦合距离,可以调谐传感器的品质因子;当耦合距离为22 μm时,品质因子可高达83。研究了所提超材料传感器对外加有机物厚度的敏感性,结果发现,频率偏移随有机物厚度增加呈指数增长,并在厚度超过10 μm之后逐渐达到饱和。此外,对外加有机物传感器的折射率传感进行了研究,结果发现,当有机物厚度为22 μm时,传感器的灵敏度约为171 GHz/RIU,FOM值约为18.3,表现出极高的灵敏度。这种高灵敏度的传感器在生物化学检测方面具有广阔的应用前景。

This study proposes a terahertz high-sensitivity sensor with a combined structure of double split-ring resonators and a metal strip as a basic unit. The destructive interference of the electromagnetic waves of the resonance rings and the metal strip with different radiation losses in far field makes the line width of the reflected resonance narrow, showing a typical asymmetric Fano-type reflection spectrum. Moreover, we verify that the quality factor of the tunable sensor can be tuned by changing the coupling distance between the double split-ring resonators and the metal strip through numerical simulations. When the coupling distance is 22 μm, the quality factor reaches 83. In addition, the sensitivity of the proposed metamaterial sensor to the analyte thickness is studied. The frequency shift exponentially increases as the thickness of the analyte increases and gradually saturates when the thickness exceeds 10 μm. Finally, we also investigate the impact of the analyte with different refractive indices on the proposed sensor. The proposed sensor exhibits extremely high refractive index sensitivity and the figure of merit, i.e., 171 GHz/RIU and 18.3, respectively, when the analyte thickness is 22 μm. This high-sensitivity sensor has extensive application prospects in biochemical detection.