Wei Na, Xu Piaorong, Yao Ye, Li Jianbo, Liu Exian, Luo Jianhua
J Opt Soc Am A Opt Image Sci Vis. 2022 May 1;39(5):800-805. doi: 10.1364/JOSAA.453467.
In this paper, a silica-based D-shaped circular photonic crystal fiber Bragg grating sensor for refractive index sensing is proposed theoretically. D-shaped fiber construction can effectively enhance the coupling effect between the guiding mode and external liquid analyte, which then causes a distinct shift in the typical reflection spectrum as the refractive index of the analyte varies. This design exhibits highly improved sensitivity of 487 nm/RIU in a large refractive index range from 1.30 to 1.40 compared with the previous fiber grating sensors. Study of the dependence of sensing performance on the structure parameters suggests that the resonance peak shifts towards longer wavelengths with the increased air-hole diameter of fiber, while it is almost immobile as the hole spacing and the number of air-hole layers change in a certain range. For the influence of the Bragg grating structure, results show that the resonance peak is not sensitive to the grating length, but linearly increases as the grating period expands. The effects of polishing depth and fiber preparation error on the sensor are also discussed in detail. This high-sensitivity sensor based on a D-shaped photonic crystal fiber and Bragg grating has great potential in biochemical detection, environmental monitoring, and medical sensing.
本文从理论上提出了一种基于二氧化硅的D形圆形光子晶体光纤布拉格光栅折射率传感传感器。D形光纤结构可以有效增强导模与外部液体分析物之间的耦合效应，进而随着分析物折射率的变化，使典型反射光谱产生明显偏移。与先前的光纤光栅传感器相比，该设计在1.30至1.40的大折射率范围内表现出高达487 nm/RIU的灵敏度。对传感性能与结构参数依赖性的研究表明，随着光纤气孔直径的增加，共振峰向更长波长移动，而在一定范围内，随着孔间距和气孔层数的变化，共振峰几乎保持不变。对于布拉格光栅结构的影响，结果表明共振峰对光栅长度不敏感，但随着光栅周期的增大而线性增加。还详细讨论了抛光深度和光纤制备误差对传感器的影响。这种基于D形光子晶体光纤和布拉格光栅的高灵敏度传感器在生化检测、环境监测和医学传感方面具有巨大潜力。
