Laser absorption spectroscopy (LAS) has become the most widely used laser spectroscopic technique for gas detection due to its capability of accurate quantification and straightforward operation. However, since resolving weak absorption and averting over-absorption are always mutually exclusive, the dynamic range of the LAS-based gas sensor is limited and insufficient for many applications in fundamental study and industry. To overcome the limitation on the dynamic range, this article reports optical pathlength (OPL) multiplexed absorption spectroscopy using a gas cell having multiple internal reflections. It organically fuses together the transmission and reflection operation modes: the former directly uses the entire OPL of the gas cell, while the latter interrogates different internal short OPLs by optical interferometry, yielding $>100$-fold OPL variation. The achieved dynamic range is more than 6 orders of magnitude that surpasses other LAS techniques by 2–3 orders of magnitude. The proposed method promotes a novel way for the development of large-dynamic-range spectroscopic gas sensors for fundamental studies and industrial applications.

中文翻译：

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通过光程多路吸收光谱法进行超宽动态范围气体传感

激光吸收光谱法（LAS）由于其准确定量和直接操作的能力而已成为气体检测中使用最广泛的激光光谱技术。但是，由于解决弱吸收和避免过度吸收始终是相互排斥的，因此基于LAS的气体传感器的动态范围有限，不足以用于基础研究和工业中的许多应用。为了克服对动态范围的限制，本文报道了使用具有多个内部反射的气室的光程（OPL）多重吸收光谱。它有机地融合了透射和反射操作模式：前者直接使用气室的整个OPL，而后者通过光学干涉法询问不同的内部短OPL，从而得出$>100$倍OPL变化。达到的动态范围超过6个数量级，比其他LAS技术高出2-3个数量级。所提出的方法为基础研究和工业应用的大动态范围光谱气体传感器的发展提供了一种新颖的方法。