基于扫描激光的腔增强吸收光谱研究

介绍了一种建立在半导体激光扫描基础上的腔增强吸收光谱技术。简要介绍了从衰荡吸收光谱技术向腔增强吸收光谱的发展及腔增强吸收光谱的实验装置,实验证明能够将 DFB 型半导体激光与高精密光学谐振腔相结合,用简单的实验装置进行高灵敏、高分辨直接吸收光谱测量。实验中,激光器的输出波长用一台波长计精确测量,当激光器的输出频率与某一腔模的频率共振时,激光被耦合到一个用两块高反射率平凹透镜(在 1.572μm 附近,R~0.994)组成的 34cm 长的高精密光学谐振腔,通过测量激光透过谐振腔后的光强,得到了二氧化碳分子在6358.654cm-1附近的吸收光谱,探测灵敏度达到了 1.2×10-5cm-1。

Study of Cavity Enhanced Absorption Spectroscopy Based on a Swept Diode Laser

In this article, cavity enhanced absorption spectroscopy based on a swept diode laser is introduced. A brief recommendation of the development of cavity ring down spectroscopy (CRDS) to cavity enhanced absorption spectroscopy (CEAS) and the experimental setup of CEAS is given. It is experimentally demonstrated that a narrow band continuous wave DFB diode laser can be used in combination with a high finesse stable cavity to perform sensitive, high resolution direct absorption spectroscopy in a simple experimental setup using ideas from the field of cavity ring down spectroscopy. Light from a scanning narrow band cw laser(DFB)is coupled into an optical cavity which consists of two high reflectivity mirrors (R≈99.4%, near 1.572μm) separated at a distance of 34cm via coincidences of the laser frequency with the frequency of the cavity mode. In a 34cm cell, the weak absorption of carbon dioxide near 6358.654cm-1 was measured and the detection sensitivity of 1.53×10-5cm-1 has been achieved.