基于光功率放大离轴腔增强光谱技术的甲烷碳同位素测量  

Measurement of Carbon Isotopes in Methane Based on Off-Axis Integrated Cavity Output Spectroscopy Technology with Booster Optical Amplifier

作　　者：余润磬 夏滑 孙鹏帅 庞涛 吴边[2] 张志荣 Yu Runqing;Xia Hua;Sun Pengshuai;Pang Tao;Wu Bian;Zhang Zhirong(School of Environmental Science and Optoelectronic Technology,University of Science and Technology of China,Hefei 230026,Anhui,China;Anhui Provincial Key Laboratory of Photonic Devices and Materials,Anhui Institute of Optics and Fine Mechanics,Hefei Institutes of Physical Science,Chinese Academy of Sciences,Hefei 230031,Anhui,China;Key Laboratory of Environmental Optics and Technology,Anhui Institute of Optics and Fine Mechanics,Hefei Institutes of Physical Science,Chinese Academy of Sciences,Hefei 230031,Anhui,China;Advanced Laser Technology Laboratory of Anhui Province,National University of Defense Technology,Hefei 230037,Anhui,China)

机构地区：[1]中国科学技术大学环境科学与光电技术学院,安徽合肥230026 [2]中国科学院合肥物质科学研究院安徽光学精密机械研究所光子器件与材料安徽省重点实验室,安徽合肥230031 [3]中国科学院合肥物质科学研究院安徽光学精密机械研究所环境光学与技术重点实验室,安徽合肥230031 [4]国防科技大学先进激光技术安徽省实验室,安徽合肥230037

出　　处：《光学学报》2024年第5期271-280,共10页Acta Optica Sinica

基　　金：国家重点研发计划(2022YFB3207601,2021YFB3201904);国家自然科学基金(11874364,41877311,42005107);安徽省重点研发项目(201904c03020005)。

摘　　要：使用中心波长为1658.7 nm的可调谐半导体分布反馈式(DFB)激光器,基于离轴积分腔光谱(OA-ICOS)技术,对激光器调谐范围内的甲烷稳定碳同位素分子13CH4和12CH4的光谱进行同时测量。选取光纤耦合助推光放大器(BOA)实现激光器输出光功率的有效放大,在保证积分腔的模式噪声不变的情况下,提高了探测器的可探测光功率,显著增加了有效光程长度,进一步提高了测量结果的信噪比。最后,通过对体积分数为500×10^(-6)的CH4标准气体进行长时间测量,当平均时间达到663 s时,同位素δ(13C)的探测极限达到0.56‰。该技术可为大气环境下甲烷中碳稳定同位素的测量提供参考。Objective As the main green energy,methane(CH_(4))has become increasingly important in human production and life.Meanwhile,as explosive and flammable harmful gas,it also causes significant problems such as production safety accidents and environmental pollution,it is particularly important to detect CH_(4) concentration in real time and online.Additionally,carbon isotopes in CH_(4) are also significant for environmental analysis of sources and sinks.Traditional isotope ratio measurement methods,such as mass spectrometry and gas chromatography,often require sample preprocessing and are difficult to achieve real-time online detection.At the same time,traditional absorption spectroscopy techniques often need large absorption cells and other devices to measure the gas isotopes,which results in difficult temperature and pressure control.We report a methane isotope measurement method based on off-axis integrated cavity output spectroscopy(OA-ICOS)technology,which eliminates residual mode noise in the measurement results by adding an RF white noise source and further expands the optical power of the incident laser using booster optical amplifier(BOA)to increase the effective optical path length of the measurement results.We hope our method can further reduce the minimum detection limit and provide solid theoretical and technical support for future measurement of isotope ratio changes in CH_(4) under atmospheric background concentration.Methods We establish a system for carbon isotope detection in CH_(4) based on OA-ICOS technology(Fig.3),and the laser output laser changes the angle and position of the incident into the integration cavity through the fiber collimator fixed on the five-dimensional adjustment frame.Meanwhile,the outgoing light after multiple reflections is formed in the cavity by the lens to converge on the photosensitive surface of the detector,and the detector converts the collected integrated light signal for photoelectric conversion.The detected electrical signal is converted analog-to-digital via the

关 键 词：光谱学 光功率放大器 离轴积分腔输出光谱技术 甲烷 碳同位素 

分 类 号：O433.1[机械工程—光学工程]