基于波长调制的离轴积分腔输出光谱技术  

Off-Axis Integrated Cavity Output Spectroscopy Technique Based on Wavelength Modulation

作　　者：吴涛[1,2] 徐冬[1,2] 何兴道[1,2] 赖荣[1,2] 程涛[1,2] 

机构地区：[1]南昌航空大学江西省光电检测技术工程实验室,江西南昌330063 [2]南昌航空大学无损检测与光电传感技术及应用国家地方联合工程实验室,江西南昌330063

出　　处：《光学学报》2017年第8期382-391,共10页Acta Optica Sinica

基　　金：国家自然科学基金(41265011);江西省研究生创新专项资金(YC2015-S330);人社部留学人员科技活动项目择优资助项目

摘　　要：介绍了基于波长调制的离轴积分腔输出光谱(WM-OA-ICOS)技术的实验装置。使用1.392μm的分布反馈式(DFB)激光器作为光源,以反射率为99.8%、相距60cm的两片镜片组成的谐振腔为气体吸收池,选择7185.87cm^(-1)的CH_4吸收谱线,对不同浓度的CH_4气体进行探测。通过优化压力、调制频率、相位和振幅等参数,并结合Allan方差,得出系统的稳定时间为203s。实验选取100s的测量时间,得出CH_4气体的探测极限为8.7×10^(-7),相应的最小的可探测吸收为2.2×10^(-6) Hz^(-1/2)。相对于离轴积分腔输出光谱技术,WM-OA-ICOS技术的灵敏度约提高了21倍。采用二次谐波峰值高度(2f)以及二次谐波峰值高度与一次谐波中值之比(2f/1f)两种方法测量CH_4气体浓度,结果发现,2f/1f方法的稳定性更好,线性度更高。An experimental device of wavelength modulated off-axis integrated cavity output spectroscopy（WM-OAICOS）technique is reported.A distributed feedback（DFB）laser with central wavelength of 1.392μm is chosen as light source.A resonant cavity is composed of two mirrors with reflectivity of 99.8% and 60 cm distance,and the cavity is used as gas absorption cell.The absorption line of CH_4 at 7185.87cm^-1 is selected to detect CH_4 with different concentrations.The stability time of the system is obtained to be 203 sby optimizing the instrument parameters（pressure,modulation frequency,phase and amplitude）combining with Allan variance.The detection limit of CH_4 is obtained to be 8.7×10^-7 by selecting the measurement time of 100 s,and the corresponding minimum detectable absorption is 2.2×10^-6 Hz^-1/2.Compared with that of off-axis integrated cavity output spectroscopy technique,the sensitivity of WM-OA-ICOS technique increases by 21 times.The second harmonic peak height and the ratio of the peak height of second harmonic to the medium of first harmonic（2f/1f）are used to measure the concentration of CH_4,and the results show that the latter has better stability and higher degree of linearity correlation.

关 键 词：光谱学 激光吸收光谱 波长调制光谱技术 离轴积分腔输出光谱 二次谐波 二次谐波与一次谐波之比 

分 类 号：O433[机械工程—光学工程]