利用寻极大值法实现布里渊光时域反射技术频移快速定位及空间分辨率增强  

Fast Positioning of Brillouin Optical Time Domain Reflectometry Frequency Shift and Enhancement of Spatial Resolution Using MaximumSeeking Method

作　　者：黄秋茗 陈映恺 刘鑫煜 陈理平 高波 付林林 李拥政 郭林峰 徐小敏[7] Huang Qiuming;Chen Yingkai;Liu Xinyu;Chen Liping;Gao Bo;Fu Linlin;Li Yongzheng;Guo Linfeng;Xu Xiaomin(School of Physics and Optoelectronic Engineering,Nanjing University of Information Science&Technology,Nanjing 210044,Jiangsu,China;Jiangsu Key Laboratory for Optoelectronic Detection of Atmosphere and Ocean,Nanjing 210044,Jiangsu,China;China Railway(Shanghai)Investment Group Co.,Ltd.,Shanghai 200126,China;Nanjing Metro Construction Co.,Ltd.,Nanjing 210019,Jiangsu,China;China Railway Tunnel Group No.2 Co.,Ltd.,Langfang 065200,Hebei,China;China Railway No.3 Group East China Construction Co.,Ltd.,Nanjing 211153,Jiangsu,China;Department of Engineering,University of Cambridge,Cambridge CB21PZ,United Kingdom)

机构地区：[1]南京信息工程大学物理与光电工程学院,江苏南京210044 [2]江苏省大气海洋光电探测重点实验室,江苏南京210044 [3]中铁(上海)投资集团有限公司,上海200126 [4]南京地铁建设有限责任公司,江苏南京210019 [5]中铁隧道集团二处有限公司,河北廊坊065200 [6]中铁三局集团华东建设有限公司,江苏南京211153 [7]剑桥大学工程系,英国剑桥CB21PZ

出　　处：《光学学报》2023年第14期75-84,共10页Acta Optica Sinica

基　　金：国家自然科学基金(62175113);江苏省重点研发计划(BE2022076)。

摘　　要：提出一种基于布里渊光时域反射(BOTDR)系统的寻极大值法,在快速傅里叶变换(FFT)和短时傅里叶变换(STFT)的基础上,实现了频移的快速定位及系统空间分辨率的增强。对时域信号进行FFT处理,利用寻极大值法判断是否存在温变或应变信息,再通过逐级选取对应长度的时域信号来确定温变或应变频移发生的位置范围;对时域信号进行STFT处理,构建三维布里渊增益谱,通过寻极大值法构建布里渊频移分布来检测短距离温变或应变,从而提高系统空间分辨率。在实验中,利用基于等分FFT的寻极大值法,对2 km待测光纤中130 m段加热光纤的位置范围进行快速定位,系统运算时间缩短到原来的1/8。同时在设置探测光脉冲宽度为100 ns的条件下,利用基于STFT的寻极大值法,在2 km待测光纤上检测到0.6 m光纤长度的温度变化,实现了亚米级别的空间分辨率。与传统BOTDR系统相比,基于寻极大值法的STFT-BOTDR系统提高了实际应用中的检测速度与空间分辨率,工程实用性得以提高。Objective In the past three decades,Brillouin optical time domain reflectometry(BOTDR)has attracted widespread attention from researchers and has been applied to health and safety monitoring in various engineering structures.BOTDR based on shorttime Fourier transform(STFT)performs signal processing on the broadband signal of the Brillouin scattering spectrum.The acquisition time of the broadband signal is shorter than that of the frequency sweep system,and therefore system response is swifter.Spatial resolution and frequency resolution are two important performance parameters of the STFTBOTDR system.The former,spatial resolution,is proportional to optical pulse width and related to the form and length of the window function.The latter is related to the signaltonoise ratio of the electrical signal,step length of frequency,center frequency of the Brillouin gain spectrum,and full width at half maximum.The two resolutions correlate with each other.Meanwhile,the computing time of the STFT is related to the set parameters of frequency step length and of the sliding window.As a result,improving the system frequency resolution will increase the system′s computing time.How can we optimize the photoelectric design and improve the efficiency of the demodulation algorithm under the current system of typical BOTDR to obtain highly enhanced spatial resolution by using economic optical pulses of common width(instead of using narrow pulses and other costly photoelectric modules)?The solution to the question is essential to the extensive and largescale application of BOTDR in the engineering field.Methods We propose a maximumseeking method based on the BOTDR system,which realizes the rapid positioning of frequency shift and the enhancement of system spatial resolution based on fast Fourier transform(FFT)and STFT.The maximumseeking method based on the equal division FFT process first performs FFT processing on the timedomain signal and linear fitting and then maximumseeking processing on the spectrum within the frequency range o

关 键 词：光纤光学 布里渊光时域反射 短时傅里叶变换 寻极大值法 定位 空间分辨率 

分 类 号：O437.2[机械工程—光学工程]