Resonant plasmonic nanostructures have attracted much attention due to their exotic optical properties. In this work, we numerically investigate single- and dual-gap ring structures, respectively, and they can be used for refractive index sensing by exciting the gap plasmon mode with sharp resonance spectra. The dual-gap ring plasmonic sensor shows the dual-channel properties and the corresponding sensitivities are 513 nm/RIU and 809 nm/RIU with the refractive indices range of 1.32–1.37, respectively. Furthermore, the gap ring structures are highly symmetrical, and have advantages in fabrication and pave the way for advanced optical devices to detect bio-molecules.

共振等离子体纳米结构由于其奇异的光学特性而备受关注。在这项工作中，我们分别对单和双间隙环结构进行了数值研究，它们可以通过用尖锐的共振光谱激发间隙等离子体模式来用于折射率传感。双间隙环形等离子体传感器显示出双通道特性，相应的灵敏度分别为 513 nm/RIU 和 809 nm/RIU，折射率范围为 1.32–1.37。此外，间隙环结构高度对称，在制造方面具有优势，为先进的光学器件检测生物分子铺平了道路。