Spectroscopy and Spectral Analysis, Volume. 35, Issue 6, 1516(2015)
Study on the Technology of the 4.4 μm Mid-Infrared Laser Heterodyne Spectrum
In this paper, first time as our knowledge, we describe the development and performance evaluation of a 4.4 μm 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 4.4 μm, 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 4.52 μm with model hop free and can be used for simultaneous detections of CO2, CO and N2O. 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 8 cm-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.
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TAN Tu, CAO Zhen-song, WANG Gui-shi, WANG Lei, LIU Kun, HUANG Yin-bo, CHEN Wei-dong, GAO Xiao-ming. Study on the Technology of the 4.4 μm Mid-Infrared Laser Heterodyne Spectrum[J]. Spectroscopy and Spectral Analysis, 2015, 35(6): 1516
Received: Mar. 28, 2014
Accepted: --
Published Online: Jun. 11, 2015
The Author Email: Tu TAN (tantu@aiofm.ac.cn)