A Methane Detection System Using Distributed Feedback Laser at 1 654 nm
LI Bin1, LIU Hui-fang1, HE Qi-xin1, ZHAI Bing1, PAN Jiao-qing2, ZHENG Chuan-tao1*, WANG Yi-ding1*
1. State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China 2. Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
Abstract：A methane (CH4) detection system based on tunable diode laser absorption spectroscopy (TDLAS) technique was experimentally demonstrated. A distributed feedback (DFB) laser around 1 654 nm, an open reflective sensing probe and two InGaAs photodiodes were adopted in the system. The electrical part of the system mainly includes the laser temperature control & modulation module and the orthogonal lock-in amplifier module. Temperature and spectrum tests on the DFB laser indicate that, the laser temperature fluctuation can be limited to the range of -0.02~0.02 ℃, the laser’s emitting wavelength varies linearly with the temperature and injection current, and also good operation stability of the laser was observed through experiments. Under a constant working temperature, the center wavelength of the laser is varied linearly by adjusting the driving current. Meanwhile, a 5 kHz sine wave signal and a 10 Hz saw wave signal were provided by the driving circuit for the harmonic extraction purpose. The developed orthogonal lock-in amplifier can extract the 1f and 2f harmonic signals with the extraction error of 3.5% and 5% respectively. By using the open optical probe, the effective optical pass length was doubled to 40 cm. Gas detection experiment was performed to derive the relation between the harmonic amplitude and the gas concentration. As the concentration increases from 1% to 5%, the amplitudes of the 1f harmonic and the 2f harmonic signal were obtained, and good linear ration between the concentration and the amplitude ratio was observed, which proves the normal function of the developed detection system. This system is capable to detect other trace gases by using relevant DFB lasers.
李 彬1，刘慧芳1，何启欣1，翟 冰1，潘教青2，郑传涛1*, 王一丁1* . 基于1 654 nm分布反馈激光器的甲烷检测系统 [J]. 光谱学与光谱分析, 2016, 36(01): 20-26.
LI Bin1, LIU Hui-fang1, HE Qi-xin1, ZHAI Bing1, PAN Jiao-qing2, ZHENG Chuan-tao1*, WANG Yi-ding1* . A Methane Detection System Using Distributed Feedback Laser at 1 654 nm. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2016, 36(01): 20-26.
