通过磁表面等离激元的多重相干提高灵敏度

Improving sensitivity by multi-coherence of magnetic surface plasmons

本文研究了一维金属纳米狭缝阵列中磁表面等离激元的相干现象,并提出了一种双谷传感方法以提高灵敏度。与通常所采用的固定入射角度进行波长扫描的方式不同,本文采用固定波长改变入射角度的方式研究表面等离激元的相干现象。由于延迟效应的存在,随着周围介质折射率的变化,两个谷会向相反的方向移动。相比于使用单一谷进行标定的方式,两个相反方向移动的谷可以有效提高灵敏度。用于标定的两个谷单独的灵敏度最大分别为39.2°/RIU和102.4°/RIU,而双谷标定的总灵敏度可达141.6°/RIU。此外,狭缝介质与上层介质的折射率不一致对传感性能的影响很小,故其有广泛的应用前景。

In this paper,we study the coherence of magnetic surface plasmons in one-dimensional metallic nano-slit arrays and propose a double-dip sensing method to improve sensitivity.Different from the conventional way of scanning wavelength at a fixed incident angle,coherence of surface plasmons is investigated by changing the incident angle at a fixed wavelength.Due to the retardation effect,two coherence dips move in opposite directions as the refractive index of the surrounding medium changes.Compared with one dip used for sensing,two oppositely moving dips can efficiently improve the sensitivity.The total sensitivity of two dips can reach 141.6°/RIU while the sensitivities of two single dips are 39.2°/RIU and 102.4°/RIU respectively.Besides,the inconsistency between the refractive index of slit medium and upper medium has few influences on the sensing performance,which will have wide practical applications.