Gas Absorption Center-Based Wavelength Calibration Technique in QEPAS System for SNR Improvement

作     者：Zongliang WANG Jun CHANG Qi LIU Cunwei TIAN Qinduan ZHANG 

作者机构：School of Physics Science and Information Technology and Shandong Key Laboratory of Optical CommunicationScience and Technology Liaocheng University Liaocheng 252000 China School of Information Science and Engineering and Shandong Provincial Key Laboratory of Laser Technology andApplication Shandong University Jinan 250100 China 

出 版 物：《Photonic Sensors》 (光子传感器（英文版）)

年 卷 期：2018年第8卷第4期

页      面：358-366页

核心收录：

学科分类：080904[工学-电磁场与微波技术] 0810[工学-信息与通信工程] 081704[工学-应用化学] 0809[工学-电子科学与技术（可授工学、理学学位）] 07[理学] 08[工学] 0817[工学-化学工程与技术] 080402[工学-测试计量技术及仪器] 070302[理学-分析化学] 0804[工学-仪器科学与技术] 081001[工学-通信与信息系统] 0703[理学-化学] 

基　　金：This work was supported by Research Fund for the Doctoral Program of Liaocheng University (Grant No. 318051543) and the National Natural Science Foundation of China (Grant No. 61475085) 

主　　题：QEPAS DFB-LD wavelength calibration fiber gas sensor 

摘      要：A simple and effective wavelength calibration scheme is proposed in a quartz enhanced photoacoustic spectroscopy （QEPAS） system for trace gas detection. A reference gas cell is connected an InGaAs photodetector for detecting the absorption intensity peak caused by the gas to calibrate the gas absorption center using distributed feedback laser diode （DFB-LD） with sawtooth wave driver current. The gas absorption wavelength calibration and gas sensing operations are conducted at a special internal to eliminate the wavelength shift of DFB-LD caused by the ambient fluctuations. Compared with the conventional wavelength modulation spectroscopy （WMS）, this method uses a lower lock-in amplifier bandwidth and averaging algorithm to improve signal noise ratio （SNR）. Water vapor is chosen as a sample gas to evaluate its performance. In the experiments, the impact of sawtooth wave frequency and lock-in amplifier bandwidth on the harmonic signal is analyzed, and the wavelength-calibration technique-based system achieves a minimum detection limit （MDL） of 790ppbv and SNR with 13.4 improvement factor compared with the conventional WMS system.