中文摘要：

在国内首次报道以窄线宽的4.4μm外腔量子级联激光（QCL）作为本地振荡光源,黑体作为辐射光源的激光外差光谱实验装置的建立和测量工作。激光外差光谱是一种高灵敏度的光谱探测技术,并可以用于发展一种小型的光谱探测系统,进行地基或星载的地球大气或天文观测。介绍了激光外差的基本理论、装置的建立和实验测量工作。此激光外差光谱实验装置采用4.4μm外腔量子级联激光,出光功率高达180mW,在4.38-4.52μm间连续可调,具有很宽的光谱调谐范围,能实现CO2,CO和N2O等大气重要分子的同时测量。通过开展不同压力下CO2气体的激光外差光谱测量,对激光外差光谱实验装置的性能进行了评估。目前该激光外差系统的信噪比达到86,低于散粒噪声极限条件的理论计算值287,系统的光谱分辨率约为0.007 8cm-1,能满足较窄线宽条件下的高分辨率激光外差光谱的测量。分析结果表明,中红外激光外差光谱系统具有很高的瞬态信噪比及光谱分辨率,在高精度测量大气温室气体的柱浓度和温室气体垂直廓线分布方面具有广阔的应用前景。

英文摘要：

In this paper,first time as our knowledge,we describe the development and performance evaluation of a 4.4μm external cavity quantum cascade laser based laser heterodyne radiometer.Laser heterodyne spectroscopy is a high sensitive laser spectroscopy technique which offers the potential to develop a compact ground or satellite based radiometer for Earth observation and astronomy.An external cavity quantum cascade laser operating at 4.4μm,with output power up to 180 mW and narrow line width was used as a local oscillation.The external cavity quantum cascade laser offers wide spectral tuning range,it is tunable from 4.38 to 4.52μm with model hop free and can be used for simultaneous detections of CO2,CO and N2 O.A blackbody was used as a signal radiation source.Development and fundamental theory of Laser heterodyne spectroscopy was described.The performance of the developed Laser heterodyne radiometer was evaluated by measuring of CO2 spectral at different pressures.Analyses results showed that a signal-to-noise ratio of 86 was achieved which was less than the theoretical value of 287.The spectral resolution of the developed Laser heterodyne spectroscopy is about 0.007 8cm-1 which could meet the requirement of high resolution spectroscopy measurement in the case of Doppler linewidth.The experiment showed that middle Infrared laser heterodyne spectroscopy system had high signal-to-noise ratio and spectral resolution,and had broad application prospect in high precision measurement of atmospheric greenhouse gas concentration and vertical profile.