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Improving sensitivity by multi-coherence of magnetic surface plasmons

 引用本文: 杨宗蒙, 邢前, 陈怡安, 侯玉敏. 通过磁表面等离激元的多重相干提高灵敏度[J]. 中国光学（中英文）.
YANG Zongmeng, XING Qian, CHEN Yian, HOU Yumin. Improving sensitivity by multi-coherence of magnetic surface plasmons[J]. Chinese Optics. doi: 10.37188/CO.EN.2022-0009
 Citation: YANG Zongmeng, XING Qian, CHEN Yian, HOU Yumin. Improving sensitivity by multi-coherence of magnetic surface plasmons[J]. Chinese Optics.

## 通过磁表面等离激元的多重相干提高灵敏度

• 中图分类号: O482.31

## Improving sensitivity by multi-coherence of magnetic surface plasmons

##### doi: 10.37188/CO.EN.2022-0009
Funds: Supported by National Natural Science Foundation of China (No. 61575006)
###### Corresponding author:ymhou@pku.edu.cn
• 摘要:

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使用双谷标定提高灵敏度的方法。与通常所采用的固定入射角度扫描波长的方式不同，这篇工作采用的是固定波长改变入射角度的方式研究了表面等离激元的相干现象。由于有延迟效应的存在，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地提高灵敏度。用于标定的两个谷的灵敏度最大分别为39.2°/RIU和102.4°/RIU，而两个谷的灵敏度可达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，可有广泛的应用。

• Figure 1.  (a) 2D schematic diagram of one-dimensional metallic nano-slit arrays structure on sapphire substrate. The period is P and the slit width is d. The width and thickness of Au slabs are a and b, respectively. The whole structure is immersed in water; (b) The reflection spectrum at normal incidence; (c)(d) The normalized magnetic field intensity distributions corresponding to the dip 1 and dip 2, respectively.

Figure 2.  Analysis of the phase difference in water (a) and substrate (b) between neighboring magnetic surface plasmon resonances in one-dimensional metallic nano-slit arrays. The red arrows represent the incident light.

Figure 3.  2D Reflection spectra of the structure in the range of $\theta = 0 \sim 60^\circ$ and $\lambda = 1000 \sim 1700\;{\rm{nm}}$; (a) Three dashed lines $C_{m = - 1}^{{\rm{water}}}$,$C_{m = 1}^{{\rm{water}}}$, and $C_{m = - 2}^{{\rm{water}}}$ represent different orders of magnetic surface plasmon coherence corresponding to the interface between metal and water, respectively. Two solid lines $C_{l = - 2}^{{\rm{sub}}}$ and $C_{l = 1}^{{\rm{sub}}}$ represent different orders of coherence corresponding to the interface between metal and substrate; (b) Positions of fixed wavelength $\lambda = 1150\;{\rm{nm}}$ and fixed incident angle $\theta = 5^\circ$ are marked by vertical and horizontal dashed lines in 2D spectrum, respectively.

Figure 4.  (a) Angle-resolved reflection spectrum at a fixed incident wavelength of 1150 nm; (b) The four graphs show the normalized magnetic field intensity distributions corresponding to the four dips A, B, C and D appearing in (a), respectively. Black arrows represent the Poynting vectors.

Figure 5.  (a) The angle-resolved reflectance spectrum obtained by changing the refractive index of the upper medium (nw=1.33 ~ 1.53) with an interval of 0.05 at the wavelength of 1150 nm; (b) The variation of each dip position with the change of refractive index; (c) Reflection spectrum is obtained by changing the wavelength when $\theta$ is fixed at 5°. As the refractive index increases, both coherence dips are red-shifted; (d) Variation of the angle difference between dip A and dip B with the change of upper medium.

Figure 6.  Comparison of the sensing performance between the refractive index of the medium in the slit is the same as that of the upper medium and the refractive index of the medium in the slit is fixed at 1.33.

##### 计量
• 文章访问数:  52
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• 被引次数: 0
##### 出版历程
• 收稿日期:  2020-01-03
• 录用日期:  2022-08-01
• 修回日期:  2020-01-05
• 网络出版日期:  2022-08-24

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