In this study, we propose a black phosphorus (BP)/waveguide terahertz plasmonic sensing structure comprising vertically stacked crystal quartz, polymethylpentene (TPX), BP, crystal quartz, and TPX layers on a germanium prism. Sharp Fano-type resonance is induced by strong coupling between the surface plasmon polariton and planar waveguide modes, and it generates imaging sensitivity of up to 9.978 $\times$ 10³ RIU⁻¹ for gas detection, with better sensing performance than other terahertz plasmonic gas sensors. Due to the in-plane anisotropic plasmonic property of BP, the proposed sensing structure exhibits optically tunable detection sensitivity and the imaging sensitivity is highly dependent on the direction. In addition, we investigated the changes in the Fano resonance and surface plasmon resonance, as well as the figure of merit for the imaging sensitivity according to structural parameters such as the thicknesses of the crystal quartz and TPX layers. Our results suggest that the proposed structure may have potential applications in gas detection in the terahertz band.

在这项研究中，我们提出了一种黑磷 (BP)/波导太赫兹等离子体传感结构，包括在锗棱镜上垂直堆叠的晶体石英、聚甲基戊烯 (TPX)、BP、晶体石英和 TPX 层。Sharp Fano 型共振由表面等离子体激元与平面波导模式之间的强耦合引起，并产生高达 9.978 的成像灵敏度 $\times$ 10 ³ RIU ^-1用于气体检测，比其他太赫兹等离子体气体传感器具有更好的传感性能。由于 BP 的面内各向异性等离子体特性，所提出的传感结构表现出光学可调的检测灵敏度，并且成像灵敏度高度依赖于方向。此外，我们根据晶体石英和 TPX 层的厚度等结构参数研究了 Fano 共振和表面等离子体共振的变化，以及成像灵敏度的品质因数。我们的结果表明，所提出的结构可能在太赫兹波段的气体检测中具有潜在的应用。