Portable difference-frequency laser-based cavity leak-out spectrometer for trace-gas analysis
Portable difference-frequency laser-based cavity leak-out spectrometer for trace-gas analysis
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DOI：
10.1007/s00340-002-0966-9
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发表时间：
2002-09
期刊：
影响因子：
--
通讯作者：
S. Stry;P. Hering;M. Mürtz
中科院分区：
文献类型：
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作者：
S. Stry;P. Hering;M. Mürtz
本文报道了一种基于全固态差频产生激光器的便携式中红外痕量气体分析光谱仪。该光谱仪通过腔漏出法（一种连续波腔衰荡技术）提供了超过3公里的原位吸收路径长度。介绍了该光谱仪的设计、性能和应用情况。该光源利用由两个单频固体激光器泵浦的周期性极化铌酸锂（PPLN）晶体中的差频产生。采用808 nm处20 mW的泵浦功率、1064 nm处660 mW的信号功率和50 mm长的PPLN晶体，在3.3 μm附近的波长区域实现了27 μW的最大功率。这相当于0.42 mW/(W2cm)的转换效率。实验证明，该便携式激光系统适合作为腔漏出光谱仪的光源。我们实现了1×10-8/cm的最小可检测吸收系数（积分时间：2 s），例如，对应于十亿分之一乙烷的检测限。这种紧凑的痕量气体分析仪具有高灵敏度和特异性，有望用于各种环境和医疗应用。
We report a portable mid-infrared spectrometer for trace-gas analysis which is based on an all-solid-state difference-frequency-generation laser. The spectrometer provides in situ absorption path lengths of more than 3 km by means of the cavity leak-out method, a cw variant of the cavity ring-down technique. The design, performance, and application of this spectrometer are presented. The light source utilizes difference-frequency generation in a periodically poled lithium niobate (PPLN) crystal pumped by two single-frequency solid-state lasers. A maximum power of 27 μW in the wavelength region near 3.3 μm is achieved using a pump power of 20 mW at 808 nm, a signal power of 660 mW at 1064 nm, and a 50-mm-long PPLN crystal. This corresponds to a conversion efficiency of 0.42 mW/(W2cm). We demonstrate that this portable laser system is suitable as a light source in a cavity leak-out spectrometer. We achieved a minimum detectable absorption coefficient of 1×10-8/cm (integration time: 2 s), corresponding, for example, to a detection limit of 1 part per billion ethane. This compact trace-gas analyzer with high sensitivity and specificity is promising for various environmental and medical applications.