Xiao Dongrui, Wang Guoqing, Yu Feihong, Liu Shuaiqi, Xu Weijie, Shao Liyang, Wang Chao, Fu Hongyan, Fu Songnian, Shum Perry Ping, Ye Tao, Song Zhangqi, Wang Weizhi
Opt Express. 2022 Feb 14;30(4):5402-5413. doi: 10.1364/OE.445982.
Curvature measurement plays an important role in structural health monitoring, robot-pose measuring, etc. High-resolution curvature measurement is highly demanded. In this paper, an optical curvature sensor with high resolution based on in-fiber Mach-Zehnder interferometer (MZI) and microwave photonic filter (MPF) is proposed and experimentally demonstrated. The in-fiber MZI is constructed with a ring-core fiber (RCF) which is fusion spliced between two coreless fibers (CLFs). The structure of CLF-RCF-CLF is then sandwiched between two segments of single-mode fiber (SMF), making the whole interferometer structure of SMF-CLF-RCF-CLF-SMF. The operating principle is that different curvatures will cause the variations of the interference spectrum of MZI due to elastic-optic effect, and then the variations are converted into the frequency-shift of the MPF. The factors affecting the visibility of the interference spectrum are researched. A preliminary exploration of the multiplexing demodulation for the in-fiber-MZIs is also investigated and discussed, which is for the first time to the best of our knowledge, holding great potential to pave the way for constructing the sensing network composed of interferometric sensors. The curvature measurement sensitivity is -147.634 MHz/m, and the resolution is 6.774 × 10 m which is the highest value up to now.
曲率测量在结构健康监测、机器人姿态测量等方面发挥着重要作用。对高分辨率曲率测量有很高的要求。本文提出并通过实验验证了一种基于光纤马赫-曾德尔干涉仪（MZI）和微波光子滤波器（MPF）的高分辨率光学曲率传感器。光纤MZI由环形芯光纤（RCF）构成，该光纤熔接在两根无芯光纤（CLF）之间。然后将CLF-RCF-CLF结构夹在两段单模光纤（SMF）之间，形成SMF-CLF-RCF-CLF-SMF的整个干涉仪结构。其工作原理是不同的曲率会由于弹光效应导致MZI干涉光谱发生变化，然后这些变化被转换为MPF的频率偏移。研究了影响干涉光谱可见度的因素。还对光纤MZIs的复用解调进行了初步探索和讨论，据我们所知这是首次进行，为构建由干涉式传感器组成的传感网络具有很大的潜力。曲率测量灵敏度为-147.634 MHz/m，分辨率为6.774×10 m，这是目前的最高值。
