基于变步长扫描策略的FBG高速解调  

High speed demodulation of FBG based on variable step scanning strategy

作　　者：梁磊[1,2] 张宇宁 杜尚明 童晓玲 Liang Lei;Zhang Yuning;Du Shangming;Tong Xiaoling(National Engineering Laboratory for Fiber Optic Sensing Technology,Wuhan University of Technology,Wuhan 430070,China;School of Information Engineering,Wuhan University of Technology,Wuhan 430070,China;Sanya Science and Education Innovation Park,Wuhan University of Technology,Sanya 572000,China)

机构地区：[1]武汉理工大学光纤传感技术国家工程实验室,湖北武汉430070 [2]武汉理工大学信息工程学院,湖北武汉430070 [3]武汉理工大学三亚科教创新园,海南三亚572000

出　　处：《红外与激光工程》2024年第4期233-242,共10页Infrared and Laser Engineering

基　　金：海南省重大科技计划项目(ZDKJ202019);三亚崖州湾科技城管理局科研项目(SKJC-2020-01-016)。

摘　　要：现有的FBG高速解调方法都各有优缺点,其中扫描式光谱分析系统通用性好、成本较低,在速度和精度上的表现较为均衡。针对扫描激光器型光纤布拉格光栅波长解调仪在实际应用中调谐次数多、扫描耗时久等问题,设计了一种变步长扫描策略,使用较少的波长调谐次数实现光谱局部峰值的检出。实验表明,在通道内只有单个光栅的情况下,使用变步长扫描策略需要扫描的点数降低了至少90%,扫描耗时减少了90%,解调速度提高至10倍。在上位机对传输的局部光谱数据进行高斯拟合解调,并对变步长扫描策略进行信噪比仿真实验测试,仿真证明变步长扫描策略适用于信噪比高于9.23 dB的情况且对后续解调的精度和平均误差几乎没有影响,具有一定的应用价值。Objective Optical fiber signal demodulation is the basis of optical fiber sensing applications,and the systems based on FBG sensing are sometimes limited by the demodulation speed when measuring the high-speed dynamically changing signal.Nowadays,the high speed demodulation method of fiber Bragg grating has become one of the main research directions of fiber demodulation.The existing FBG high-speed demodulation methods have their own advantages and disadvantages.Among them,the scanning spectral analysis system has good versatility,low cost,and more balanced performance in speed and accuracy.Therefore,improving the demodulation speed of the scanning laser fiber Bragg grating demodulation system has become the research goal of this paper.Methods A variable step scanning strategy is designed to solve the problems such as many tuning times and long scanning time in the practical application of the laser based fiber Bragg grating wavelength demodulation instrument.The crest of the spectrum can be extracted by using the variable step scanning strategy with less wavelength tuning times.The variable step scanning strategy first uses OTSU algorithm to calculate the threshold and the coarse scanning step size in the initialization stage.In the demodulation stage,the global coarse scan is performed to extract the approximate range of the wave crest,and then the local point-by-point scan is performed in the sampling points exceeding the threshold.Only the spectral sampling data of point-by-point scanning in the local range needs to be uploaded to the supreme computer for peak searching,the amount of data required for peak searching is reduced.Results and Discussions A FBG wavelength demodulation system based on modulated grating Y-branch(MGY)laser was built(Fig.3),and demodulation test was carried out after calibration of the laser.Gaussian fitting demodulation was carried out on the host computer software for the transmitted local spectral data,and the signalto-noise ratio simulation experiment was conducted on the variable

关 键 词：光纤光栅 高速解调 可调谐激光器 波长调谐 

分 类 号：TP212[自动化与计算机技术—检测技术与自动化装置]