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Li R, Li J, Song Z, He D, Li F, Yu F, Lin X. A nonparametric point-by-point method to measure time-dependent frequency in wavelength modulation spectroscopy. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2024; 324:124949. [PMID: 39153344 DOI: 10.1016/j.saa.2024.124949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2024] [Revised: 07/09/2024] [Accepted: 08/07/2024] [Indexed: 08/19/2024]
Abstract
A nonparametric point-by-point (NPP) method is presented for high-accuracy measurement of the time-dependent frequency (laser frequency) in tunable laser absorption spectroscopy, crucial for ensuring ultimate measurement accuracy. In wavelength modulation spectroscopy in particular, the parametric methods in current use for time-dependent frequency measurement are insufficiently accurate and are difficult to apply to complex modulation scenarios. Based on a multi-scale viewpoint, point-by-point measurement of the frequency is realized by linear superposition of the frequency information mapped from the interferometric signal on a unit scale and on a local scale. Validation experiments indicate that the measurement accuracy of the proposed NPP method is three times that of the existing parametric methods, while effectively immunizing against non-ideal tuning effects. Additionally, the NPP method is suitable for use with arbitrarily complex modulations such as square wave modulation, for which parametric methods are inapplicable.
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Affiliation(s)
- Renjie Li
- State Key Laboratory of High Temperature Gas Dynamics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China; School of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jing Li
- China Academy of Aerospace Aerodynamics, Beijing 100074, China
| | - Ziyu Song
- State Key Laboratory of High Temperature Gas Dynamics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China
| | - Dong He
- State Key Laboratory of High Temperature Gas Dynamics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China; Deep Space Exploration Laboratory / Department of Modern Mechanics, University of Science and Technology of China, Hefei 230026, China
| | - Fei Li
- State Key Laboratory of High Temperature Gas Dynamics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China.
| | - Fei Yu
- Key Laboratory of Materials for High Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
| | - Xin Lin
- State Key Laboratory of High Temperature Gas Dynamics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China
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Elimination of Scintillation Noise Caused by External Environment Disturbances in Open Space. PHOTONICS 2022. [DOI: 10.3390/photonics9060415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
External environment disturbances in open space cause scintillation noise in tunable diode laser absorption spectroscopy (TDLAS), which is used to detect the concentration of gases in air. However, most gases analyzed by TDLAS are present in trace amounts in air. Thus, useful information is typically submerged in strong noise, thereby reducing the detection accuracy. Herein, a method is proposed to eliminate the scintillation noise caused by external environment disturbances in open space. First, the submerged signal is detected via fast coarse-tuning filtering. Then, scintillation noise is eliminated through the extraction and reconstruction of the main feature information. Thereafter, the background signal is obtained by unequal precision. Furthermore, adaptive iterative fitting is performed. Finally, an experimental setup is established for atmospheric detection in an open optical path. The experimental results show that the COD and RSS fitted using the traditional method are 0.87859 and 1.5772 × 10−5, respectively, and those fitted using the proposed method are 0.91448 and 8.81639 × 10−6, respectively. The field results imply that the proposed method has improved accuracy for detecting trace gases in open space and can be employed for practical engineering applications.
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Li S, Sun L. Natural logarithm wavelength modulation spectroscopy: A linear method for any large absorbance. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021; 254:119601. [PMID: 33676345 DOI: 10.1016/j.saa.2021.119601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 01/15/2021] [Accepted: 02/05/2021] [Indexed: 06/12/2023]
Abstract
In this paper, we proposed the technique of Natural Logarithm Wavelength Modulation Spectroscopy (ln-WMS). Unlike conventional WMS, the amplitudes of the harmonics are linear to the absorbance regardless how large it is. The treating method used in ln-WMS is taking the natural logarithm of the transmitted intensity. The key to ln-WMS is to find out the demodulation phase. We introduced the η-seeking algorithm, which works to find the demodulation phase η so that the 1st harmonic of the unabsorbed intensity comes to zero. Then the nth harmonic of the absorbed intensity is demodulated at phase nη. With simulations, we validated the effectiveness of ln-WMS as well as illustrated the shapes of 1st, 2nd and 3rd harmonics. Then we utilized ln-WMS for measuring water vapor experimentally. It turns out that the linearity is established between the amplitudes of the 1st, 2nd and 3rd harmonics and concentration, although the absorbance is as large as 0.76. We evaluated the stability of the system with coefficient of variation and Allan deviation analysis, proved the effectiveness of the η-seeking algorithm and investigated how the modulation amplitude influenced the amplitudes of the harmonics.
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Affiliation(s)
- Shaomin Li
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing 100084, China
| | - Liqun Sun
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing 100084, China.
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Li S, Sun L. Measurement of broadband absorbers in the near-infrared region based on Wavelength Modulation United Absorption Spectroscopy. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021; 247:119127. [PMID: 33161262 DOI: 10.1016/j.saa.2020.119127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 10/18/2020] [Accepted: 10/20/2020] [Indexed: 06/11/2023]
Abstract
Molecules without well-resolved absorption spectra within a certain spectral range can be called broadband absorbers. Inspired by Wavelength Modulation Spectroscopy (WMS), we came up the idea of Wavelength Modulation United Absorption Spectroscopy (WM-UAS) for measuring broadband absorbers. WM-UAS commonly involves two gases, one is the probe gas, another is the target broadband absorber. The only request for implementing WM-UAS is that, within the spectral envelope of the broadband absorber, there exists more than one well-resolved absorption peak of the probe gas. To validate the effectiveness of WM-UAS, methanol was experimentally measured with water vapor as the probe gas. According to Allan deviation analysis, the detection limit was estimated as 1.7 ppm during the optimal average time of 5.4 s. For standard methanol vapor with a concentration of 100.9 ppm, the measurement error was about 1.3%@5.4 s, and for high purity nitrogen, the measurement result was 3.56 ppm@5.4 s.
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Affiliation(s)
- Shaomin Li
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments, Tsinghua University, Beijing 100084, China
| | - Liqun Sun
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments, Tsinghua University, Beijing 100084, China.
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Deng H, Li M, He Y, Xu Z, Yao L, Chen B, Yang C, Kan R. Laser heterodyne spectroradiometer assisted by self-calibrated wavelength modulation spectroscopy for atmospheric CO 2 column absorption measurements. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2020; 230:118071. [PMID: 31958604 DOI: 10.1016/j.saa.2020.118071] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 11/29/2019] [Accepted: 01/11/2020] [Indexed: 06/10/2023]
Abstract
We have developed a laser heterodyne spectroradiometer in combination with self-calibrated wavelength modulation spectroscopy based on a software-based lock-in amplifier to observe the atmospheric carbon dioxide (CO2) column absorption near wavelength 1.57 μm in solar occultation mode. This combination facilitates miniaturization of laser heterodyne radiometer. Combined with our developed retrieval algorithm, the atmospheric carbon dioxide column concentration is measured to be 413.7 ± 1.9 ppm, in agreement with GOSAT satellite observation results. This system offers high spectral signal-to-noise ratio of ~333 for the zeroth harmonic (0f) normalized second harmonic (R2f) signal of CO2 transition (R22e), with a measurement averaging time of 8 s, which can be further improved by increasing averaging time in accordance to the Allan deviation analysis for the noise fluctuation. This demonstrates the feasibility of the system for atmospheric investigation and the potential of ground-based, airborne and spaceborne observations for the variation of the global greenhouse gases.
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Affiliation(s)
- Hao Deng
- Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, Anhui 230031, China; University of Science and Technology of China, Hefei, Anhui 230022, China
| | - Mingxing Li
- Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, Anhui 230031, China; University of Science and Technology of China, Hefei, Anhui 230022, China
| | - Yabai He
- Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, Anhui 230031, China
| | - Zhenyu Xu
- Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, Anhui 230031, China
| | - Lu Yao
- Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, Anhui 230031, China
| | - Bing Chen
- Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, Anhui 230031, China
| | - Chenguang Yang
- Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, Anhui 230031, China.
| | - Ruifeng Kan
- Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, Anhui 230031, China; Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China.
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Du Y, Peng Z, Ding Y. A high-accurate and universal method to characterize the relative wavelength response (RWR) in wavelength modulation spectroscopy (WMS). OPTICS EXPRESS 2020; 28:3482-3494. [PMID: 32122015 DOI: 10.1364/oe.383216] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 01/17/2020] [Indexed: 06/10/2023]
Abstract
Considering the importance of the laser wavelength response and the difficulty in its real-scenario measurement in WMS, a high-accuracy and universal method was developed to characterize the relative wavelength response (RWR) by analyzing the laser current response. A coupling term that depends on both the current scan and the modulation characteristic was introduced to describe the coupling effect between the wavelength scan and modulation. The accuracy of the proposed method was verified with different laser working conditions and scan waveforms. All fitting residuals of the RWR result from the proposed method are smaller than 0.1% of the total scan range and the fitting residual of the ramp scanned WMS is twice smaller than the minimum value from literature. The better calibration-free 2f/1f fitting and more accurate CO2 concentration results also suggest the high accuracy and superiority of the proposed method. Finally, based on the precise prediction of RWR with small scan and modulation indices, the spectral parameters, including line strength and self-collisional broadening coefficient, of CO2 transition at 6976.2026 cm-1 were successfully measured using WMS.
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Laser Absorption Sensing Systems: Challenges, Modeling, and Design Optimization. APPLIED SCIENCES-BASEL 2019. [DOI: 10.3390/app9132723] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Laser absorption spectroscopy (LAS) is a promising diagnostic method capable of providing high-bandwidth, species-specific sensing, and highly quantitative measurements. This review aims at providing general guidelines from the perspective of LAS sensor system design for realizing quantitative species diagnostics in combustion-related environments. A brief overview of representative detection limits and bandwidths achieved in different measurement scenarios is first provided to understand measurement needs and identify design targets. Different measurement schemes including direct absorption spectroscopy (DAS), wavelength modulation spectroscopy (WMS), and their variations are discussed and compared in terms of advantages and limitations. Based on the analysis of the major sources of noise including electronic, optical, and environmental noises, strategies of noise reduction and design optimization are categorized and compared. This addresses various means of laser control parameter optimization and data processing algorithms such as baseline extraction, in situ laser characterization, and wavelet analysis. There is still a large gap between the current sensor capabilities and the demands of combustion and engine diagnostic research. This calls for a profound understanding of the underlying fundamentals of a LAS sensing system in terms of optics, spectroscopy, and signal processing.
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Yang C, Mei L, Deng H, Xu Z, Chen B, Kan R. Wavelength modulation spectroscopy by employing the first harmonic phase angle method. OPTICS EXPRESS 2019; 27:12137-12146. [PMID: 31052758 DOI: 10.1364/oe.27.012137] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 04/03/2019] [Indexed: 06/09/2023]
Abstract
Wavelength modulation spectroscopy (WMS), widely employed in tunable diode laser absorption spectroscopy (TDLAS), has been accomplished by employing the first harmonic phase angle (1f-PA) method that is immune to the laser intensity and the demodulation phase. The principle of the 1f-PA method has been demonstrated by the phasor decomposition method, which indicates that the 1f-PA is linearly proportional to the integral absorption in the approximation of weak absorption. Validation experiments have been performed to investigate the relationship between the 1f-PA and the modulation amplitude/frequency by measuring the absorption line of CO2 around 6362.5 cm-1. The peak-to-peak value of the 1f-PA decreases with the increasing of the modulation amplitude, and is particularly apparent under small modulation amplitudes and high modulation frequencies. The 1f-PA shows good linearity with the increasing of the CO2 concentration. Comparing with the traditional first harmonic normalized second harmonic (2f/1f) method, higher detection sensitivities can be achieved at high modulation frequencies. The promising results imply that the 1f-PA method has a great potential in the applications of the WMS technique especially under high modulation frequencies or modulation-amplitude limited conditions, such as strong turbulence or high pressure environments.
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Wang G, Mei J, Tian X, Liu K, Tan T, Chen W, Gao X. Laser frequency locking and intensity normalization in wavelength modulation spectroscopy for sensitive gas sensing. OPTICS EXPRESS 2019; 27:4878-4885. [PMID: 30876097 DOI: 10.1364/oe.27.004878] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Accepted: 02/01/2019] [Indexed: 06/09/2023]
Abstract
A novel method for laser frequency locking and intensity normalization in wavelength modulation spectroscopy (WMS)-based gas sensor system is reported. The center spacing between two second harmonic peaks demodulated from the rising and falling edges of a scanning triangular wave (for wavelength scan) is employed as a frequency locking reference. Amplitude of the directly acquired sine signal (for wavelength modulation) in the spectral region far away from the absorption feature is employed as an intensity normalization reference. A 50 ppm CH4:N2 sample sealed in a multi-pass cell at 1 atm was employed as the target analyte for demonstration. The frequency locking significantly improves measurement accuracy, and the introduced intensity normalization method realized a ~3 times SNR improvement as compared to the commonly used 1f normalization method under frequency locking conditions. A minimum measurement precision of ~2.5 ppbv was achieved with a normalized noise equivalent absorption coefficient of 1.8 × 10-9 cm-1Hz-1/2.
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Liu J, Zhou Y, Guo S, Hou J, Zhao G, Ma W, Wu Y, Dong L, Zhang L, Yin W, Xiao L, Axner O, Jia S. A novel methodology to directly pre-determine the relative wavelength response of DFB laser in wavelength modulation spectroscopy. OPTICS EXPRESS 2019; 27:1249-1261. [PMID: 30696194 DOI: 10.1364/oe.27.001249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 12/07/2018] [Indexed: 06/09/2023]
Abstract
A novel methodology to directly pre-determine the relative wavelength response (RWR) of a DFB laser, in terms of a combined current linearly scanned wavelength response and current modulated wavelength response (CMWR), in wavelength modulation spectroscopy (WMS) is presented. It is shown that the assessed RWR can be used to mimic the measured response with standard deviation of discriminations that are below 3.4 × 10-3cm-1 under a variety of conditions. It is also shown that its performance supersedes two commonly used assessment models of the CMWR but is slightly worse than that of the third model, however with the benefit of solely using a single fitting parameter (the concentration) instead of more. When the novel method is applied to the assessment of CO2 concentration in a Herriot-type multipass cell by using the technique of calibration-free WMS, the results show that there is virtually no difference compared to that by use of the best of the other methods. It is concluded that the novel method is more robust and simplifies the retrieval process of gas concentration.
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Martín-Mateos P, Bonilla-Manrique OE, Gutiérrez-Escobero C. Wavelength modulation laser heterodyne radiometry. OPTICS LETTERS 2018; 43:3009-3012. [PMID: 29905746 DOI: 10.1364/ol.43.003009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 05/24/2018] [Indexed: 06/08/2023]
Abstract
A novel method is proposed for improving the performance of traditional laser heterodyne radiometry. The technique, which is based on the use of a wavelength modulated local oscillator laser, provides baseline-free spectra, lower limits of detection, and better precision and consistency than the conventional approach. This tool could, therefore, boost the accuracy of current terrestrial and planetary atmospheric studies.
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Zhao G, Tan W, Jia M, Hou J, Ma W, Dong L, Zhang L, Feng X, Wu X, Yin W, Xiao L, Axner O, Jia S. Intensity-Stabilized Fast-Scanned Direct Absorption Spectroscopy Instrumentation Based on a Distributed Feedback Laser with Detection Sensitivity down to 4 × 10 -6. SENSORS (BASEL, SWITZERLAND) 2016; 16:E1544. [PMID: 27657082 PMCID: PMC5038816 DOI: 10.3390/s16091544] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Revised: 09/14/2016] [Accepted: 09/14/2016] [Indexed: 12/02/2022]
Abstract
A novel, intensity-stabilized, fast-scanned, direct absorption spectroscopy (IS-FS-DAS) instrumentation, based on a distributed feedback (DFB) diode laser, is developed. A fiber-coupled polarization rotator and a fiber-coupled polarizer are used to stabilize the intensity of the laser, which significantly reduces its relative intensity noise (RIN). The influence of white noise is reduced by fast scanning over the spectral feature (at 1 kHz), followed by averaging. By combining these two noise-reducing techniques, it is demonstrated that direct absorption spectroscopy (DAS) can be swiftly performed down to a limit of detection (LOD) (1σ) of 4 × 10-6, which opens up a number of new applications.
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Affiliation(s)
- Gang Zhao
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China; (G.Z.); (W.T.); (M.J.); (J.H.); (L.D.); (L.Z.); (W.Y.); (L.X.); (S.J.)
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
| | - Wei Tan
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China; (G.Z.); (W.T.); (M.J.); (J.H.); (L.D.); (L.Z.); (W.Y.); (L.X.); (S.J.)
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
| | - Mengyuan Jia
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China; (G.Z.); (W.T.); (M.J.); (J.H.); (L.D.); (L.Z.); (W.Y.); (L.X.); (S.J.)
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
| | - Jiajuan Hou
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China; (G.Z.); (W.T.); (M.J.); (J.H.); (L.D.); (L.Z.); (W.Y.); (L.X.); (S.J.)
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
| | - Weiguang Ma
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China; (G.Z.); (W.T.); (M.J.); (J.H.); (L.D.); (L.Z.); (W.Y.); (L.X.); (S.J.)
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
- Department of Physics, Umeå University, Umeå SE-901 87, Sweden;
| | - Lei Dong
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China; (G.Z.); (W.T.); (M.J.); (J.H.); (L.D.); (L.Z.); (W.Y.); (L.X.); (S.J.)
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
| | - Lei Zhang
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China; (G.Z.); (W.T.); (M.J.); (J.H.); (L.D.); (L.Z.); (W.Y.); (L.X.); (S.J.)
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
| | - Xiaoxia Feng
- Department of Electrical Engineering and Automation, Shanxi Polytechnic College, Taiyuan 030006, China;
| | - Xuechun Wu
- Shanxi Guohui Optoelectronic Technology CO., Ltd., Taiyuan 030006, China;
| | - Wangbao Yin
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China; (G.Z.); (W.T.); (M.J.); (J.H.); (L.D.); (L.Z.); (W.Y.); (L.X.); (S.J.)
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
| | - Liantuan Xiao
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China; (G.Z.); (W.T.); (M.J.); (J.H.); (L.D.); (L.Z.); (W.Y.); (L.X.); (S.J.)
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
| | - Ove Axner
- Department of Physics, Umeå University, Umeå SE-901 87, Sweden;
| | - Suotang Jia
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China; (G.Z.); (W.T.); (M.J.); (J.H.); (L.D.); (L.Z.); (W.Y.); (L.X.); (S.J.)
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
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