Broadband time-domain absorption spectroscopy with a ns-pulse supercontinuum source
Broadband time-domain absorption spectroscopy with a ns-pulse supercontinuum source
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DOI：
10.1364/oe.18.022762
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发表时间：
2010-10-25
期刊：
影响因子：
3.8
通讯作者：
Leipertz, Alfred
中科院分区：
文献类型：
--
作者：
Sych, Yaroslav;Engelbrecht, Rainer;Leipertz, Alfred
已经开发并测试了一种基于 Q 开关激光的系统，用于 1390-1740 nm (7200-5750 cm(-1)) 范围内的宽带吸收光谱。在光谱仪中，25 kHz 重复频率微芯片 Nd:YAG 激光器的 1064 nm 光被引导到光子晶体光纤中，以产生宽光谱范围内的短（约 2 ns）辐射脉冲。该辐射通过 25 公里长的色散单模光纤，以便在光纤输出端以约 140 ns 的时间间隔传播相应的波长。这种快速扫频光源允许通过传输光功率的时间分辨检测来记录气体吸收光谱。实现的光谱分辨率约为2 cm(-1)。给出了在 CO2:CH4:N-2 气体混合物的电池中记录的光谱示例。描述了一种用于根据混合物组分的具有不重叠吸收带的光谱来评估不同物质的摩尔浓度的算法。评估由于所需平均而在不同采集时间检索到的浓度值的不确定性。例如，可以在毫秒时间尺度实时获得信噪比足够大的光谱，以提供相对误差为 5% 的物质浓度。讨论了该技术的潜力和局限性。 (C) 2010 美国光学学会
A Q-switched laser based system for broadband absorption spectroscopy in the range of 1390-1740 nm (7200-5750 cm(-1)) has been developed and tested. In the spectrometer the 1064 nm light of a 25 kHz repetition-rate micro-chip Nd:YAG laser is directed into a photonic crystal fiber to produce a short (about 2 ns) pulse of radiation in a wide spectral range. This radiation is passed through a 25 km long dispersive single-mode fiber in order to spread the respective wavelengths over a time interval of about 140 ns at the fiber output. This fast swept-wavelength light source allows to record gas absorption spectra by temporally-resolved detection of the transmitted light power. The realized spectral resolution is about 2 cm(-1). Examples of spectra recorded in a cell with CO2:CH4:N-2 gas mixtures are presented. An algorithm employed for the evaluation of molar concentrations of different species from the spectra with non-overlapping absorption bands of mixture components is described. The uncertainties of the concentration values retrieved at different acquisition times due to the required averaging are evaluated. As an example, spectra with a signal-to-noise ratio large enough to provide species concentrations with a relative error of 5% can be obtained in real time at a millisecond time scale. Potentials and limitations of this technique are discussed. (C) 2010 Optical Society of America