摘要
提出一种利用极大倾角光纤光栅(Ex-TFG)谐振峰的3 dB点进行悬臂梁低频振动检测的优化方法。对Ex-TFG的轴向应变和弯曲应变特性进行理论分析和实验验证;对基于光强调制的Ex-TFG振动传感的光谱响应特性进行理论分析,采用Ex-TFG谐振峰的3 dB点对振动进行实验研究。实验结果表明:1)Ex-TFG在轴向应变和弯曲应变条件下,其谐振波长均发生蓝移,横电(TE)模和横磁(TM)模的轴向应变灵敏度分别为-2.8 pm/με和-1.8 pm/με,透射强度基本不变,在0~0.4 m-1的曲率范围内基于光强变化的弯曲应变灵敏度分别为2.6 dB/m-1和1.2 dB/m-1,基于波长漂移的弯曲应变灵敏度分别为-3.34 nm/m-1和-2.53 nm/m-1;2)在低频振动的检测中,Ex-TFG的TE模和TM模的谐振峰3 dB点的振动加速度灵敏度分别为113.54 mV/g和100.93 mV/g,比谐振峰的峰值波长点(100%点)的振动加速度灵敏度高2倍多,且信噪比(SNR)高约10 dB。此外,SNR随悬臂梁厚度的增大而增大;3)在相同条件下,TE模具有比TM模更高的振动响应灵敏度,但TM模比TE模具有更好的输出稳定性。
This study proposes an optimization method for detecting the low-frequency vibration of a cantilever beam using the 3 dB point of the resonant peak of an excessively tilted fiber grating(Ex-TFG).First,the axial and bending strain characteristics of Ex-TFG are theoretically analyzed and experimentally verified.The spectral response characteristics of the Ex-TFG vibration sensor modulated by light intensity are also theoretically analyzed.The 3 dB point of the Ex-TFG resonance peak is proposed to detect the vibration signal,and subsequently,a corresponding experimental research is conducted.The results are as follows.First,the resonance wavelength of Ex-TFG is blue shifted owing to both axial and bending strains.The axial strain sensitivities are-2.8 and-1.8 pm/μεfor the TE and TM modes,respectively,whereas the transmission intensity remains unchanged.Bending strain sensitivities based on the light intensity modulation in the curvature range of 0-0.4 m-1 are 2.6 dB/m-1 and 1.2 dB/m-1,respectively.Bending strain sensitivities based on wavelength shift are-3.34 nm/m-1 and-2.53 nm/m-1,respectively.Second,during vibration detection,the vibration acceleration sensitivities of the resonance peaks of Ex-TFG at the 3 dB points are 113.54 and 100.93 mV/g for the TE and TM modes,respectively,which are over two times higher than those(100%point)of the resonance peaks.The signal-to-noise ratios(SNRs)of the TE and TM modes at the 3 dB point are also higher(approximately 10 dB)than those(100%point)of the resonance peaks.In addition,the SNR increases with the increasing cantilever beam thickness.Third,under the same condition,the TE mode exhibits higher vibration response sensitivity than the TM mode;however,the output of the TM mode has better stability than the TE mode.
作者
罗彬彬
谢浪
王亚杰
邹雪
石胜辉
叶露
蒋上海
赵明富
汪治华
Luo Binbin;Xie Lang;Wang Yajie;Zou Xue;Shi Shenghui;Ye Lu;Jiang Shanghai;Zhao Mingfu;Wang Zhihua(Chongqing Key Laboratory of Optical Fiber Sensor and Photoelectric Detection,Chongqing University of Technology,Chongqing 400054,China)
出处
《光学学报》
EI
CAS
CSCD
北大核心
2019年第8期75-84,共10页
Acta Optica Sinica
基金
国家自然科学基金(61875026,61505017)
重庆市科委前沿与基础项目(cstc2018jcyjAX0122,cstc2015jcyjA40035,cstc2015jcyjA40051)
重庆市教育委员会科学技术研究项目(KJQN201801121)
重庆理工大学创新基金(ycx2018231).
关键词
光纤光学
光纤光栅
轴向应变
弯曲应变
振动传感
等强度悬臂梁
fiber optics
fiber grating
axial strain
bending strain
vibration sensing
equal strength cantilever beam