基于柔性空芯光纤的NO与NO_(2)中红外吸收光谱检测(特邀)  

Mid-Infrared Absorption Spectroscopy for NO and NO_(2) Detection in a Flexible Hollow Core Fiber(Invited)

作　　者：温大新 高丽梅 段锟 吉雍彬 石艺尉[2] 任伟 Wen Daxin;Gao Limei;Duan Kun;Ji Yongbin;Shi Yiwei;Ren Wei(Department of Mechanical and Automation Engineering,The Chinese University of Hong Kong,Hong Kong 999077,China;School of Information Science and Engineering,Fudan University,Shanghai 200433,China)

机构地区：[1]香港中文大学机械与自动化工程学系,中国香港999077 [2]复旦大学信息科学与工程学院,上海200433

出　　处：《激光与光电子学进展》2024年第3期42-48,共7页Laser & Optoelectronics Progress

基　　金：国家自然科学基金(52122003);香港研资局优配研究金(14208221);香港研资局协作研究金(C4002-22Y)。

摘　　要：报道了一种基于柔性空芯光纤和量子级联激光器(QCL)的中红外吸收光谱技术,可同时检测NO和NO_(2)气体。QCL在间歇连续波(i CW)模式下运行,结合柔性空芯光纤具有小型化传感器的潜力。分别选择1929.03 cm^(-1)和1599.91 cm^(-1)的吸收线用于NO和NO_(2)检测,两束激光同时耦合到内径为530μm的100 cm长的柔性空芯光纤中。直接吸收光谱首先用于展示双气体检测,QCL以iCW模式运行并结合时分复用技术,然后采用一次谐波归一化的波长调制光谱来消除非气体吸收带来的信号强度变化的影响,并研究了气体传感器的性能。对于体积分数为50×10^(-6)的NO与15×10^(-6)的NO_(2),检测精度分别评估为5.2%和4.1%。当积分时间为60 s时NO的检测限为39×10^(-9),当积分时间为50 s时NO_(2)的检测限为9.2×10^(-9)。In this study,we report the application of mid-infrared absorption spectroscopy for simultaneous gas sensing of NO and NO_(2) using a flexible hollow core fiber(HCF)and two quantum cascade lasers(QCLs).The utilization of QCLs with intermittent continuous wave(iCW)operations and a flexible hollow-core optical fiber can miniaturize sensor systems.The optimal absorption lines for NO and NO_(2) detection were selected at approximately 1929.03 cm^(−1) and 1599.91 cm^(−1),respectively.Both laser beams were simultaneously coupled into a 100 cm flexible HCF with an inner diameter of 530μm.Initially,direct absorption spectroscopy was performed as an intuitive demonstration of the iCW operation of QCLs with a time-division multiplexing(TDM)strategy for dual-species detection.Following this,we applied wavelength modulation spectroscopy using the first harmonic normalized second harmonic(2f/1f)method to eliminate the influence of any nonabsorption intensity variation,thereby enabling us to thoroughly investigate the performance of the gas sensor.The precision of NO and NO_(2) detection was estimated by measuring the concentrations of 50×10^(-6) NO and 15×10^(-6) NO_(2).Results indicated a precision of 5.2%for NO and 4.1%for NO_(2).Furthermore,we achieved minimum detection limits of 39×10^(-9) NO with a 60 s integration time and 9.2×10^(-9) NO_(2) with a 50 s integration time.

关 键 词：激光吸收光谱 柔性空芯光纤 间歇连续波 一氧化氮 二氧化氮 

分 类 号：O433.1[机械工程—光学工程]