Characterization of a swept external cavity quantum cascade laser for rapid broadband spectroscopy and sensing
Characterization of a swept external cavity quantum cascade laser for rapid broadband spectroscopy and sensing
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DOI：
10.1364/oe.23.025553
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发表时间：
2015-10-05
期刊：
影响因子：
3.8
通讯作者：
Phillips, Mark C.
中科院分区：
文献类型：
--
作者：
Brumfield, Brian E.;Taubman, Matthew S.;Phillips, Mark C.
研究了快速扫描外腔量子级联激光器（ECQCL）系统与开路Herriott细胞的结合，用于测量具有宽吸收光谱和窄吸收光谱的化学物质的时间分辨。在200 Hz的采集速率下获得了1278 - 1390 cm（-1）的光谱窗口，对应于2x10(4) cm(-1)/s的调谐速率，光谱分辨率为0.2 cm（-1）。ECQCL能够在毫秒时间尺度上测量一氧化二氮（N2O）和1,1,1,2-四氟乙烷（F134A）浓度< 100 ppbv的变化，这在开放路径Herriott细胞附近的模拟羽流研究中得到了证明。使用ECQCL系统测量的吸收光谱显示噪声等效吸收系数为5 × 10(-9) cm(-1)Hz（-1/2）。在5 ms的频谱采集时间内，测量到N2O和F134A的噪声等效浓度（NEC）分别为70和16 ppbv，平均为100 s后提高到亚ppbv水平。估计(NO)-O-2和F134A在1秒内的噪声等效柱密度分别为0.64和0.25 ppmv x m。(C)2015美国光学学会
The performance of a rapidly swept external cavity quantum cascade laser (ECQCL) system combined with an open-path Herriott cell was evaluated for time-resolved measurements of chemical species with broad and narrow absorption spectra. A spectral window spanning 1278 - 1390 cm(-1) was acquired at a 200 Hz acquisition rate, corresponding to a tuning rate of 2x10(4) cm(-1)/s, with a spectral resolution of 0.2 cm(-1). The capability of the ECQCL to measure < 100 ppbv changes in nitrous oxide (N2O) and 1,1,1,2-tetrafluoroethane (F134A) concentrations on millisecond timescales was demonstrated in simulated plume studies with releases near the open-path Herriott cell. Absorbance spectra measured using the ECQCL system exhibited noise-equivalent absorption coefficients of 5x10(-9) cm(-1)Hz(-1/2). For a spectrum acquisition time of 5 ms, noise-equivalent concentrations (NEC) for N2O and F134A were measured to be 70 and 16 ppbv respectively, which improved to sub-ppbv levels with averaging to 100 s. Noise equivalent column densities of 0.64 and 0.25 ppmv x m in 1 sec are estimated for (NO)-O-2 and F134A. (C)2015 Optical Society of America