Tian Chuan, Chen Xuening, Ren Yaqi, Yang Yuxing, Wang Meng, Bai Xiaolei
School of Physical Science and Technology, Inner Mongolia University, Hohhot 010021, China.
Sensors (Basel). 2024 May 17;24(10):3184. doi: 10.3390/s24103184.
The U-shaped fiber configuration represents the elementary form of micro-displacement sensing, characterized by its exceptional freedom and flexibility. The study proposes the U-shaped bent single-mode-multimode-single-mode (SMS) fiber structure that integrates the multimode interference (MMI) effect for enhanced mode dispersion and the Mach-Zönder interference (MZI) effect for spectral sensitivity improvement. The transmission spectral properties of the U-shaped SMS fiber structure with a bent radius over 1 cm are experimentally measured as the change in displacement varied within the range of 5 mm in this work. As the radius decreases, the spectrum shows redshift, which is related to the central wavelength of the peak or dips-a smaller wavelength results in a stronger redshift for the same displacement change. The average sensitivity of micro-displacement measurement within a range of 5 mm is 5.41 pm/μm, and the linearity is 99.62%. The maximum sensitivity of U-shaped SMS fiber structure is 34.46 pm/μm, with the minimum displacement change of approximately 5.804 nm. The transmission spectral properties of the U-shaped SMS fiber structure within the ranges of 50 μm, 500 μm, and 5 mm are experimentally measured in this work. This experiment observed a relatively uniform spectral drift pattern in a large range of micro-displacement sensing. The measurement range is limited by the limited spectral range of the light source and the discontinuous variation in the effective refractive index. This provides an experimental reference for further understanding the characteristics of U-shaped fiber structures and applying its application in micro-displacement sensing.
U形光纤结构代表了微位移传感的基本形式，其特点是具有非凡的自由度和灵活性。该研究提出了一种U形弯曲单模-多模-单模（SMS）光纤结构，它集成了多模干涉（MMI）效应以增强模式色散，以及马赫-曾德尔干涉（MZI）效应以提高光谱灵敏度。在这项工作中，实验测量了弯曲半径超过1 cm的U形SMS光纤结构的传输光谱特性，位移变化范围在5 mm以内。随着半径减小，光谱出现红移，这与峰值或凹陷的中心波长有关——对于相同的位移变化，波长越小，红移越强。在5 mm范围内的微位移测量平均灵敏度为5.41 pm/μm，线性度为99.62%。U形SMS光纤结构的最大灵敏度为34.46 pm/μm，最小位移变化约为5.804 nm。在这项工作中，实验测量了U形SMS光纤结构在50 μm、500 μm和5 mm范围内的传输光谱特性。该实验在大范围的微位移传感中观察到了相对均匀的光谱漂移模式。测量范围受光源光谱范围有限和有效折射率的不连续变化限制。这为进一步了解U形光纤结构的特性及其在微位移传感中的应用提供了实验参考。
