Light transmission mechanisms in a SMF-capillary fiber-SMF structure and its application to bi-directional liquid level measurement
Light transmission mechanisms in a SMF-capillary fiber-SMF structure and its application to bi-directional liquid level measurement
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SMF-毛细管光纤-SMF结构中的光传输机制及其在双向液位测量中的应用
DOI：
10.1364/oe.456917
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发表时间：
2022
期刊：
影响因子：
3.8
通讯作者：
Pengfei Wang
中科院分区：
文献类型：
--
作者：
Ziyi Huang;Dejun Liu;Qiang Wu;Ke Tian;Haoyu Zhao;changyu shen;Gerald Farrell;Yuliya Semenova;Pengfei Wang
毛细管光纤（CF）在单模光纤（SMF）-CF-SMF（SCS）传感结构中得到了广泛的研究，因为通过简单地调节CF的空气芯直径（包层直径）和长度可以容易地激发多个光导机制。理解SCS结构中的光导原理对于改进基于CF的光纤传感器的实现是至关重要的。本文从理论和实验两个方面研究了大空芯直径（≥ 20 μm）和长CF（> 1 mm）的导光原理。研究发现，在传输结构中，SCS结构中多模干涉（MMI）和抗共振反射光波导（ARROW）光波导机制都被激发。然而，在实验中，由于小空芯CF的大传输损耗，在空芯直径小于50 μm的CF的光谱中没有观察到MMI下降。进一步的实验结果表明，空气芯直径越大的碳纤维对曲率的灵敏度越高，当使用CF-100时，灵敏度达到最高，为-16.15nm/m-1。此外，我们首次提出了一种用于高灵敏度双向液位测量的SMF-CF-20-CF-30-SMF（SCCS）结构。两种类型的ARROW倾角（Dip-20和Dip-30）在传输中同时激发，因此可以通过分别跟踪Dip-20和Dip-30的倾角强度变化来检测液位和液体流动方向。
Capillary fiber (CF) has been extensively investigated in a singlemode fiber (SMF)-CF-SMF (SCS) sensing structure since multiple light guiding mechanisms can be easily excited by simply tuning the air core diameter (cladding diameter) and length of the CF. Understanding the light guiding principles in an SCS structure is essential for improved implementation of a CF based fiber sensor. In this work, light guiding principles in a relatively large air core diameter (≥ 20 µm) and long length of CF (> 1 mm) are investigated theoretically and experimentally. It is found that both multimode interference (MMI) and Anti-Resonant Reflecting Optical Waveguide (ARROW) light guiding mechanisms are excited in the SCS structure in the transmission configuration. However, MMI dips are not observed in the spectrum for the air core diameters of CF smaller than 50 µm in the experiment due to large transmission loss in small air core CFs. Further experimental results demonstrate that a CF with a bigger air core diameter shows a higher sensitivity to curvature, and the highest sensitivity of -16.15 nm/m -1 is achieved when an CF-100 was used. In addition, a SMF-CF-20-CF-30-SMF (SCCS) structure is proposed for high sensitivity bi-direction liquid level measurement for the first time, to the best of our knowledge. Two types of ARROW dips (Dip-20 and Dip-30) are simultaneously excited in transmission, hence both liquid level and liquid flow direction can be detected by tracing the dip strength changes of Dip-20 and Dip-30, respectively.