基于V型腔增强吸收光谱技术的一氧化碳检测研究

论文基于光反馈原理及V型增强腔技术,结合量子串级激光器,搭建了CO吸收光谱检测系统.研究并实现了光反馈效应(反馈相位自动可调)、偶数和奇数腔模式效应、激光器阈值电流降低效应.系统有效反射率达到99.979%,在物理长度为47 cm的光腔内实现了4.48 km有效吸收路径.通过自动调节V型腔长,使光谱分辨率从0.005 3 cm~(-1)提高到0.001 1 cm~(-1).通过阿伦方差分析,确定了最高信噪比的积分时间为53 s.气体压强40 torr,温度20°C时,系统对CO(R(6)吸收线)检测准确度及检测极限分别达到(97.79±0.07)%和(0.49±0.04)ppb.也分析和证明了气体压强对CO的峰值吸收强度、检测准确度及检测极限的影响.

Detection of CO based on V-shaped cavity-enhanced absorption spectroscopy

In this paper, based on optical feedback theory and V-shaped cavity-enhanced absorption spectroscopy, combined with quantum cascade laser, a detection system for CO was built up. The optical feedback effect, even and odd modes effect, and threshold current lowering effect were studied and achieved. The effective reflectivity of 99.979% and the effective absorption path of 4.48 km in a cavity with physical length of 47 cm were obtained. Though adjusting the length of V-shaped cavity automatically, the spectral resolution was improved to 0.0011 cm-1 from 0.0053 cm-1. With the best integration time of 53 s obtained by allan variance, this optical system allows detection for the R(6) band of CO with high accuracy of 97.79±0.07% and the detection limit of 0.49±0.04 ppb at pressure of 40 torr and temperature of 20 °C. The effects of gas pressure on the absorption peak value, detection accuracy and detection limit for CO were also analyzed and demonstrated.