基于游标效应的多纵模拍频光纤轴向应变传感技术研究  

Fiber-optic Axial Strain Sensing Based on Multi-longitudinal Mode Beat Frequency with Vernier Effect

作　　者：田孝忠 沈潺潺 秦敬平 富馨瑶 王恒 梁兰菊 TIAN Xiaozhong;SHEN Chanchan;QIN Jingping;FU Xinyao;WANG Heng;LIANG Lanju(School of Opto-electronic Engineering,Zaozhuang University,Zaozhuang 221700,China;Zaozhuang Key Laboratory of Environmental Catalysis and Pollution Control,School of City and Architecture Engineering,Zaozhuang University,Zaozhuang 221700,China)

机构地区：[1]枣庄学院光电工程学院,枣庄221700 [2]枣庄学院城市与建筑工程学院,枣庄市环境催化与污染控制重点实验室,枣庄221700

出　　处：《光子学报》2024年第12期155-163,共9页Acta Photonica Sinica

基　　金：国家自然科学基金(Nos.61701434,61735010);山东省自然科学基金(No.ZR2019PB031)。

摘　　要：为了提高基于多纵模拍频解调技术的光纤传感系统灵敏度,将游标效应引入其中,通过一支光纤光栅、掺铒光纤和两支法拉第反射镜构成两个线型腔激光器,在两个线型腔间设置长度差异实现多纵模拍频信号的游标效应。追踪游标包络变化恢复外界物理量,借助游标效应的放大原理,提高了传感灵敏度。以光纤轴向应变解调为例进行了实验验证,结果表明,两个线型腔的多纵模拍频信号周期分别为6.97 MHz和7.52 MHz条件下,产生了周期为95.06 MHz的游标包络。在单个线型腔中,选择追踪频率为1.50694 GHz时,传感灵敏度为-1.228 kHz/με,在游标效应下,选择追踪频率为1.52424 GHz时,其传感灵敏度为-17.23 kHz/με,灵敏度提高了14.09倍,与理论计算较为吻合。With the advantages of high sensitivity,simple structure,and low cost,the multi-longitudinal mode beat frequency technique has attracted considerable attention since it was first proposed in 2010.The fundamental mechanism behind this technique is that numerous multi-longitudinal modes within the fiber laser bandwidth are stimulated and beat with each other to generate a Beat Frequency Signal(BFS).The Free Spectrum Range(FSR)of the BFS is related to the propagation time in the fiber laser cavity,thus the applied parameters on fibers can be recovered by tracking the change of selected BFS.Compared with traditional optical fiber sensors interrogated in the optical domain,the BFS can be detected in the frequency domain.Benefitting from the large frequency gap between the optical signal and frequency signal and the mature electronic instrument,the interrogation resolution and speed can be enhanced greatly.The sensitivity of BFS is proportional to the selected frequency.In other words,in order to improve the sensitivity,high-frequency BFS should be chosen,which brings instability and low measurement range.The vernier effect is an effect method to improve the sensitivity in optical fiber interferometers.The vernier envelope can be generated by combining two interference spectrums with different FSRs.Hence,the measurements can be recovered by monitoring the vernier envelope with an enhanced sensitivity.Up to now,researchers have applied the vernier effect to measure parameters,including temperature,strain,refractive index,etc.It should be noted that the vernier effect magnifies the sensitivity but also the measurement error,resulting that the vernier effect is appropriate for the applications with a damage threshold.Essentially,the vernier effect is formed by two periodic signals with different periods,it also can be generated in the frequency domain.In this paper,the vernier effect is introduced to the multi-longitudinal mode beat frequency technique to enhance the sensing sensitivity.To verify the proposed method,optic

关 键 词：传感器 光纤传感 多纵模拍频 游标效应 轴向应变 

分 类 号：TN29[电子电信—物理电子学]