摘要
介绍了用DFB型可调谐半导体激光器做光源的腔增强吸收光谱(TDL-CEAS)技术.简要介绍了腔增强吸收光谱的发展和实验设计,从法布里-珀罗腔的角度解释了腔增强吸收光谱的有效吸收路径,阐述了腔增强吸收光谱具有高灵敏度的主要原因是腔内介质能够获得很长的吸收光程;用中心波长为1.573μm的DFB型可调谐近红外半导体激光器做光源,用两块高反射率平凹透镜(1.573μm附近,反射率约99.4%,凹面曲率半径为1 m)组成的光学谐振腔做吸收池,采用同时扫描激光和谐振腔的方法,在34 cm长的吸收池内测得了CO2分子在1.573μm附近的弱吸收谱线,探测灵敏度达1.66×10-5cm-1.实验结果表明,腔增强吸收光谱具有灵敏度高、分辨率高、实验装置简单、易于操作等优点.
The Cavity enhanced absorption spectroscopy based on a tunable DFB diode laser （TDL-CEAS） was described. A brief introduction of cavity enhanced absorption spectroscopy development and experimental scheme was given, the effective absorption path of the medium in the optical cavity was interpreted from the way of Fabry-Perot cavity. It is pointed out that the main reason why CEAS has high detection sensitivity is that the medium in the cavity can get a long absorption path. A tunable DFB diode laser which center wavelength is 1. 573 μm was used as the light source, and an optical cavity which consists of two high reflectivity mirrors （ near 1. 573 μm, R about 0. 994） separated at a distance of 34 cm was used as the absorption cell. Laser radiation was coupled into the optical cavity via accidental coincidences of laser frequency with the cavity mode when scanning the cavity and the laser. An absorption spectrum of carbon dioxide near 1. 573 μm was obtained and a detection sensitivity of about 1.66 × 10 ^-5 cm^-1 was achieved. It is experimentally demonstrated that the CEAS is a highly sensitive and high resolution spectrum technology, and it has the advantage of simple experimental setup and easy operation.
基金
Project supported by the National High Technology Research and Development Program of China (2004AA825100) and Natural Science Foundation of Anhui Province (03045301).
