Wang Fupeng, Wu Jinghua, Liang Rui, Wang Qiang, Wei Yubin, Cheng Yaopeng, Li Qian, Cao Diansheng, Xue Qingsheng
Faculty of Information Science and Engineering, Engineering Research Center of Advanced Marine Physical Instruments and Equipment, Ocean University of China, Qingdao 266100, China.
State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China.
Sensors (Basel). 2023 May 26;23(11):5107. doi: 10.3390/s23115107.
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 CH absorption center of 1653.72 nm with a fluctuation of fewer than 19.7 MHz. For 500 ppm CH 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.
在波长调制光谱（WMS）气体检测系统中，激光二极管通常通过电流注入驱动并稳定在恒定温度下。因此，每个WMS系统都不可或缺一个高精度温度控制器。为消除波长漂移影响并提高检测灵敏度和响应速度，有时需要将激光波长锁定在气体吸收中心。在本研究中，我们将温度控制器开发到0.0005°C的超高稳定水平，并在此基础上提出一种新的激光波长锁定策略，成功将激光波长锁定在1653.72nm的CH吸收中心，波动小于19.7MHz。对于500ppm的CH样品检测，借助锁定的激光波长，1σ信噪比从71.2dB提高到80.5dB，峰峰值不确定度从1.95ppm提高到0.17ppm。此外，波长锁定的WMS相对于传统的波长扫描WMS系统还具有快速响应的绝对优势。
