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 

机构地区：[1]School of Physics Science and Information Technology and Shandong Key Laboratory of Optical CommunicationScience and Technology, Liaocheng University, Liaocheng 252000, China [2]School of Information Science and Engineering and Shandong Provincial Key Laboratory of Laser Technology andApplication, Shandong University, Jinan 250100, China

出　　处：《Photonic Sensors》2018年第4期358-366,共9页光子传感器（英文版）

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）.

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.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.

关 键 词：QEPAS DFB-LD wavelength calibration fiber gas sensor 

分 类 号：TN929.533[电子电信—通信与信息系统] O657.32[电子电信—信息与通信工程]