中国物理B ›› 2022, Vol. 31 ›› Issue (9): 94207-094207.doi: 10.1088/1674-1056/ac5d33

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High-sensitivity methane monitoring based on quasi-fundamental mode matched continuous-wave cavity ring-down spectroscopy

Zhe Li(李哲)1,2, Shuang Yang(杨爽)1, Zhirong Zhang(张志荣)1,3,4,†, Hua Xia(夏滑)1, Tao Pang(庞涛)1, Bian Wu(吴边)1, Pengshuai Sun(孙鹏帅)1, Huadong Wang(王华东)1, and Runqing Yu(余润磬)1,2   

  1. 1 Anhui Provincial Key Laboratory of Photonic Devices and Materials, Anhui Institute of Optics and Fine Mechanics, HFIPS, Chinese Academy of Sciences, Hefei 230031, China;
    2 University of Science and Technology of China, Hefei 230026, China;
    3 Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, HFIPS, Chinese Academy of Sciences, Hefei 230031, China;
    4 Advanced Laser Technology Laboratory of Anhui Province, Hefei 230037, China
  • 收稿日期:2021-12-03 修回日期:2022-03-07 接受日期:2022-03-14 出版日期:2022-08-19 发布日期:2022-09-03
  • 通讯作者: Zhirong Zhang E-mail:zhangzr@aiofm.ac.cn
  • 基金资助:
    This research is financial supported by the Natural National Science Foundation of China (Grant Nos. 11874364, 41877311, and 42005107), the National Key Research and Development Program of China (Grant No. 2017YFC0805004), and the CAS & Bengbu Technology Transfer Project (Grant No. ZKBB202102).

High-sensitivity methane monitoring based on quasi-fundamental mode matched continuous-wave cavity ring-down spectroscopy

Zhe Li(李哲)1,2, Shuang Yang(杨爽)1, Zhirong Zhang(张志荣)1,3,4,†, Hua Xia(夏滑)1, Tao Pang(庞涛)1, Bian Wu(吴边)1, Pengshuai Sun(孙鹏帅)1, Huadong Wang(王华东)1, and Runqing Yu(余润磬)1,2   

  1. 1 Anhui Provincial Key Laboratory of Photonic Devices and Materials, Anhui Institute of Optics and Fine Mechanics, HFIPS, Chinese Academy of Sciences, Hefei 230031, China;
    2 University of Science and Technology of China, Hefei 230026, China;
    3 Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, HFIPS, Chinese Academy of Sciences, Hefei 230031, China;
    4 Advanced Laser Technology Laboratory of Anhui Province, Hefei 230037, China
  • Received:2021-12-03 Revised:2022-03-07 Accepted:2022-03-14 Online:2022-08-19 Published:2022-09-03
  • Contact: Zhirong Zhang E-mail:zhangzr@aiofm.ac.cn
  • Supported by:
    This research is financial supported by the Natural National Science Foundation of China (Grant Nos. 11874364, 41877311, and 42005107), the National Key Research and Development Program of China (Grant No. 2017YFC0805004), and the CAS & Bengbu Technology Transfer Project (Grant No. ZKBB202102).

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摘要： Continuous-wave cavity ring-down spectroscopy (CW-CRDS) is an important technical means to monitor greenhouse gases in atmospheric environment. In this paper, a CW-CRDS system is built to meet the needs of atmospheric methane monitoring. The problem of mode matching is explained from the perspective of transverse mode and longitudinal mode, and the influence of laser injection efficiency on measurement precision is further analyzed. The results of cavity ring-down time measurement show that the measurement precision is higher when the laser is coupled with the fundamental mode. In the experiment, DFB laser is used to calibrate the system with standard methane concentration, and the measurement residual is less than ±4×10-4 μs-1. The methane concentration in the air is monitored in real time for two days. The results show the consistency of the concentration changes over the two days, which further demonstrates the reliability of the system for the measurement of trace methane. By analyzing the influence of mode matching, it not only assists the adjustment of the optical path, but also further improves the sensitivity of the system measurement.

关键词: continuous-wave cavity ring-down spectroscopy (CW-CRDS), cavity modes, coupling efficiency, mode matching, greenhouse gas

Abstract: Continuous-wave cavity ring-down spectroscopy (CW-CRDS) is an important technical means to monitor greenhouse gases in atmospheric environment. In this paper, a CW-CRDS system is built to meet the needs of atmospheric methane monitoring. The problem of mode matching is explained from the perspective of transverse mode and longitudinal mode, and the influence of laser injection efficiency on measurement precision is further analyzed. The results of cavity ring-down time measurement show that the measurement precision is higher when the laser is coupled with the fundamental mode. In the experiment, DFB laser is used to calibrate the system with standard methane concentration, and the measurement residual is less than ±4×10-4 μs-1. The methane concentration in the air is monitored in real time for two days. The results show the consistency of the concentration changes over the two days, which further demonstrates the reliability of the system for the measurement of trace methane. By analyzing the influence of mode matching, it not only assists the adjustment of the optical path, but also further improves the sensitivity of the system measurement.

Key words: continuous-wave cavity ring-down spectroscopy (CW-CRDS), cavity modes, coupling efficiency, mode matching, greenhouse gas

中图分类号:  (Laser spectroscopy)

  • 42.62.Fi
42.55.Px (Semiconductor lasers; laser diodes) 42.79.-e (Optical elements, devices, and systems) 42.25.Hz (Interference)