A highly tunable design for obtaining double resonance enhanced surface-enhanced Raman spectroscopy (SERS) substrates with ultrasmall vertical nanogaps is proposed by utilizing the plasmonic Fano resonances resulted from the strong coupling between the broad gap plasmon mode of the Au nanocavity and the narrow surface plasmons polaritons. A sandwiched plasmonic nanocavity of Au nanostrip grating upon a gold film separated by a dielectric spacer of nanopillar with ultrasmall nanogap is designed and simulated to obtain the double resonances at the laser excitation and Raman scattering frequencies for Raman signals detection. We demonstrate that by tuning the geometrical and material parameters of the proposed nanocavity, the double resonance frequencies and the SERS enhancement can be readily controlled. Our proposed plasmonic nanocavity exhibits very high SERS enhancement factor up to 1.1$\times$10¹⁰, which are promising for detect specific signals of sport doping drugs and medical diagnoses.

通过利用由金纳米腔的宽间隙等离子体模式与窄表面等离子体激元之间的强耦合产生的等离子体 Fano 共振，提出了一种高度可调的设计，用于获得具有超小垂直纳米间隙的双共振增强表面增强拉曼光谱 (SERS) 衬底极化子。设计并模拟了金膜上的 Au 纳米带光栅的夹层等离子体纳米腔，金膜由具有超小纳米间隙的纳米柱的介电间隔物隔开，以获得激光激发和拉曼散射频率下的双共振，用于拉曼信号检测。我们证明，通过调整所提出的纳米腔的几何和材料参数，可以很容易地控制双共振频率和 SERS 增强。$\times$10 ¹⁰，有望用于检测运动兴奋剂药物和医学诊断的特定信号。