Ultra-Stable Temperature Controller-Based Laser Wavelength Locking for Improvement in WMS Methane Detection
Fupeng Wang,
Jinghua Wu,
Rui Liang,
Qiang Wang,
Yubin Wei,
Yaopeng Cheng,
Qian Li,
Diansheng Cao,
Qingsheng Xue
Affiliations
Fupeng Wang
Faculty of Information Science and Engineering, Engineering Research Center of Advanced Marine Physical Instruments and Equipment, Ocean University of China, Qingdao 266100, China
Jinghua Wu
Faculty of Information Science and Engineering, Engineering Research Center of Advanced Marine Physical Instruments and Equipment, Ocean University of China, Qingdao 266100, China
Rui Liang
Faculty of Information Science and Engineering, Engineering Research Center of Advanced Marine Physical Instruments and Equipment, Ocean University of China, Qingdao 266100, China
Qiang Wang
State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China
Yubin Wei
Laser Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250102, China
Yaopeng Cheng
Faculty of Information Science and Engineering, Engineering Research Center of Advanced Marine Physical Instruments and Equipment, Ocean University of China, Qingdao 266100, China
Qian Li
Faculty of Information Science and Engineering, Engineering Research Center of Advanced Marine Physical Instruments and Equipment, Ocean University of China, Qingdao 266100, China
Diansheng Cao
Faculty of Information Science and Engineering, Engineering Research Center of Advanced Marine Physical Instruments and Equipment, Ocean University of China, Qingdao 266100, China
Qingsheng Xue
Faculty of Information Science and Engineering, Engineering Research Center of Advanced Marine Physical Instruments and Equipment, Ocean University of China, Qingdao 266100, China
In the wavelength modulation spectroscopy (WMS) gas detection system, the laser diode is usually stabilized at a constant temperature and driven by current injection. So, a high-precision temperature controller is indispensable in every WMS system. To eliminate wavelength drift influence and improve detection sensitivity and response speed, laser wavelength sometimes needs to be locked at the gas absorption center. In this study, we develop a temperature controller to an ultra-high stability level of 0.0005 °C, based on which a new laser wavelength locking strategy is proposed to successfully lock the laser wavelength at a CH4 absorption center of 1653.72 nm with a fluctuation of fewer than 19.7 MHz. For 500 ppm CH4 sample detection, the 1σ SNR is increased from 71.2 dB to 80.5 dB and the peak-to-peak uncertainty is improved from 1.95 ppm down to 0.17 ppm with the help of a locked laser wavelength. In addition, the wavelength-locked WMS also has the absolute advantage of fast response over a conventional wavelength-scanned WMS system.