中国物理B ›› 2026, Vol. 35 ›› Issue (3): 34206-034206.doi: 10.1088/1674-1056/adfa79

• • 上一篇    下一篇

Nonlinear relationship between signal and gas concentration in high-precision off-axis integrated cavity output spectroscopy

Xinxin Wei(韦欣欣), Biao Ye(叶标), Yi Jiao(焦一), Xin Meng(孟鑫), and Jingjing Wang(王静静)†   

  1. School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou 221116, China
  • 收稿日期:2025-05-20 修回日期:2025-07-25 接受日期:2025-08-12 出版日期:2026-02-11 发布日期:2026-03-12
  • 通讯作者: Jingjing Wang E-mail:jjwang@jsnu.edu.cn
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 62005108 and 62205134), Xuzhou Science and Technology Plan Project (Grant No. KC23078), and the Research and Innovation Plan for Graduate Students in Jiangsu Province, China (Grant Nos. KYCX25 3165 and KYCX24 3016).

Nonlinear relationship between signal and gas concentration in high-precision off-axis integrated cavity output spectroscopy

Xinxin Wei(韦欣欣), Biao Ye(叶标), Yi Jiao(焦一), Xin Meng(孟鑫), and Jingjing Wang(王静静)†   

  1. School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou 221116, China
  • Received:2025-05-20 Revised:2025-07-25 Accepted:2025-08-12 Online:2026-02-11 Published:2026-03-12
  • Contact: Jingjing Wang E-mail:jjwang@jsnu.edu.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 62005108 and 62205134), Xuzhou Science and Technology Plan Project (Grant No. KC23078), and the Research and Innovation Plan for Graduate Students in Jiangsu Province, China (Grant Nos. KYCX25 3165 and KYCX24 3016).

RichHTML

0

PDF (PC)

2

赞

摘要： Off-axis integrated cavity output spectroscopy (OA-ICOS) is an extremely sensitive technique for measuring trace gas concentrations. Nevertheless, recent research has indicated that when the reflectivity of the mirrors forming the cavity is excessively high, it affects the linearity between the absorption signal and concentration. In this study, the causes and limitations of this phenomenon are discussed based on the Beer-Lambert law and the law of light propagation within the cavity. A new equation is derived to describe the nonlinear relationship between the integral area of absorption spectra and gas concentration. The absorption spectra of CO$_{2}$ and CH$_{4}$, measured under different experimental conditions and concentrations, were fitted with Voigt functions to obtain parameters such as peak values and integral areas, which were used to verify the theoretical derivation process and results. The experimental results demonstrate that the relationship between the area of the measured absorption spectra and the gas concentration is consistent with the new formula, with an average fitting correlation coefficient of 0.9998. Meanwhile, the experimental results also demonstrate that the effective optical path length indeed decreases with increasing concentration. Furthermore, the cavity reflectances (99.99644% at 6242.6 cm$^{-1}$ and 99.99833% at 6046.96 cm$^{-1}$) derived from the fitting coefficient of the new concentration expression closely match the reflectances (99.99727% at 6242.6 cm$^{-1}$ and 99.99868% at 6046.96 cm$^{-1}$) obtained by applying the classical formula to the spectra of the lowest gas concentration. These experimental results validate the theoretical deduction process and expression. This research provides insights for the theoretical and practical advancements of OA-ICOS, which is significant for advancing high-precision trace gas detection technology.

关键词: integrated cavity output spectroscopy, trace gas concentration, mirrors reflectivity, nonlinear relationship, Beer-Lambert law

Abstract: Off-axis integrated cavity output spectroscopy (OA-ICOS) is an extremely sensitive technique for measuring trace gas concentrations. Nevertheless, recent research has indicated that when the reflectivity of the mirrors forming the cavity is excessively high, it affects the linearity between the absorption signal and concentration. In this study, the causes and limitations of this phenomenon are discussed based on the Beer-Lambert law and the law of light propagation within the cavity. A new equation is derived to describe the nonlinear relationship between the integral area of absorption spectra and gas concentration. The absorption spectra of CO$_{2}$ and CH$_{4}$, measured under different experimental conditions and concentrations, were fitted with Voigt functions to obtain parameters such as peak values and integral areas, which were used to verify the theoretical derivation process and results. The experimental results demonstrate that the relationship between the area of the measured absorption spectra and the gas concentration is consistent with the new formula, with an average fitting correlation coefficient of 0.9998. Meanwhile, the experimental results also demonstrate that the effective optical path length indeed decreases with increasing concentration. Furthermore, the cavity reflectances (99.99644% at 6242.6 cm$^{-1}$ and 99.99833% at 6046.96 cm$^{-1}$) derived from the fitting coefficient of the new concentration expression closely match the reflectances (99.99727% at 6242.6 cm$^{-1}$ and 99.99868% at 6046.96 cm$^{-1}$) obtained by applying the classical formula to the spectra of the lowest gas concentration. These experimental results validate the theoretical deduction process and expression. This research provides insights for the theoretical and practical advancements of OA-ICOS, which is significant for advancing high-precision trace gas detection technology.

Key words: integrated cavity output spectroscopy, trace gas concentration, mirrors reflectivity, nonlinear relationship, Beer-Lambert law

中图分类号:  (Spectral absorption by atmospheric gases)

  • 42.68.Ca
07.88.+y (Instruments for environmental pollution measurements) 42.62.Fi (Laser spectroscopy) 95.85.Jq (Near infrared (0.75-3 μm))