基于外差相敏色散光谱技术的宽动态范围甲烷气体检测  

Measurement of methane concentration with wide dynamic range using heterodyne phase-sensitive dispersion spectroscopy

作　　者：周晨 马柳昊 王宇[1] ZHOU Chen;MA Liu-hao;WANG Yu(School of Automotive Engineering,Wuhan University of Technology,Wuhan 430070,China;State Key Laboratory of Applied Optics,Changchun Institute of Optics,Fine Mechanics and Physics,Chinese Academy of Sciences,Changchun 130033,China)

机构地区：[1]武汉理工大学汽车工程学院,湖北武汉430070 [2]中国科学院长春光学精密机械与物理研究所应用光学国家重点实验室,吉林长春130033

出　　处：《中国光学（中英文）》2024年第4期789-800,共12页Chinese Optics

基　　金：国家自然科学基金项目(No.52106221);中国科学院长春光学精密机械与物理研究所应用光学国家重点实验室开放基金项目(No.SKLA02022001A05)。

摘　　要：为实现痕量甲烷气体的宽动态范围高灵敏度检测,本文开展了双边带拍频抑制模式的外差相敏色散光谱技术研发,研究了电光调制器工作特性以及偏置电压调控方法,对比了抑制与非抑制模式下的色散相位谱轮廓与信噪比,并对检测性能(如线性动态检测范围)进行了系统研究。基于近红外分布式反馈激光器和电光调制器,搭建了外差相敏色散甲烷气体检测系统,通过探索和分析电光调制器的最佳工作区间,实现了双边带拍频抑制进而得到了大幅值、高信噪比的色散相位信号。测量了典型高频(1.2 GHz)强度调制下甲烷/氮气标气的色散相位信号,获取了色散相位信号峰峰值随气体浓度的变化规律。同时开展了波长调制光谱技术实验,对两种技术的线性度、检测动态范围和对光功率波动的抗干扰性能进行对比研究。最后,通过测量不同浓度的标气验证了该系统在宽动态、快速时间响应下的性能。所开发的基于外差相敏色散光谱技术的甲烷检测系统具有线性度高(R^(2)=0.9999),动态检测范围宽(38.5 ppm~40%),且对光功率波动免疫性高的显著优势。本文研发的基于外差相敏色散光谱技术的气体检测技术在宽动态范围检测和实际现场检测应用领域具有广阔的前景。In this paper,we developed a dual-sideband beat-suppressed heterodyne phase-sensitive disper-sion spectroscopy(HPSDS)for sensitive detection of trace gases across a wide dynamic range and explored the operational characteristics of the electro-optic modulator(EOM)and bias voltage control methods under sideband suppression mode.The dispersion phase spectral profiles and the corresponding signal-to-noise ra-tios in both suppression and non-suppression modes were compared before a comprehensive evaluation of the detection performance.A HPSDS-based detection system was developed based on a near-infrared distributed feedback laser and an EOM.The suppression of the dual-sideband beat was achieved by exploring and ana-lyzing the optimal operational range of the EOM,leading to the optimization of dispersion phase signals with increased amplitude and high signal-to-noise ratio.The dispersion phase signals under typical high-fre-quency(1.2 GHz)intensity modulation were recorded for different standard methane/nitrogen mixtures.The relationship between the peak-to-peak values of the dispersion phase signals and the varied gas concentra-tions was then summarized.Meanwhile,wavelength modulation spectroscopy(WMS)experiments were con-ducted;subsequently,the HPSDS and WMS techniques’performances were compared in terms of linearity,dynamic detection range,and immunity to optical power fluctuations.Finally,the HPSDS-based system's performance under a wide dynamic range and rapid time response was verified by measuring different con-centrations of standard gases.Experimental results indicate that the HPSDS technique exhibits high linearity(R^(2)=0.9999),a wide dynamic range(38.5 ppm to 40%),and remarkable immunity to optical power fluctu-ations.The dual-sideband-beat-suppression-HPSDS-based methane sensor developed in this paper shows great potential for applications involving wide dynamic range detection and on-site practical trace gas detec-tion.

关 键 词：相敏检测 色散光谱 双边带拍频抑制 甲烷检测 宽动态范围 

分 类 号：O433.54[机械工程—光学工程]