研究了在三开口劈裂金属纳米环中，当入射场偏振方向不同时出现的多极局域表面等离激元共振现象及折射率传感特性。研究表明，当入射场偏振方向分别沿x轴和y轴时，在可见光-近红外区域分别激发起两个和三个明显的共振峰。通过改变缺口的张角，能够实现对共振峰位和强度的可控调整。共振峰位处劈裂纳米环的近场分布表明，LHA(左半弧)和 DRHA(双右半弧)之间等离激元的杂化耦合是形成上述共振的原因。劈裂纳米环的多极共振非常适合折射率传感应用。当改变周围环境折射率，入射场沿x轴偏振时，折射率敏感度的最大值可达到1365nm/RIU；入射场沿y轴偏振时，折射率敏感度最大值可达2229nm/RIU。%Metallic split-ring resonators with three gaps are studied in this paper. There are multipolar localized surface plasmon resonances in the spectra for different incident polarizations, and the refractive index sensing performances are also studied. It is shown that there are two and three prominent resonances in the visible light and near infrarad region when the incident polarization is along the x- and the y-axis, respectively. The resonance position and intensity can be well tuned by adjusting the angle between the gaps. Near field enhancement distributions of the split-ring resonators at the resonance peak reveal that plasmon hybridization between the the LHA (left half arc) and DRHA (double right arc) causes the multipolar resonances. The multipolar resonances are very suitable for refractive index sensing applications. It is shown that when the incident polarization is along x-axis, the maximum sensitivity of the refractive index is about 1365nm/RIU and when the polarization is along y-axis, the maximum sensitivity can be as large as 2229nm/RIU.
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