We present an all-fiber-based laser gas analyzer (LGA) employing quartz-enhanced photoacoustic spectroscopy (QEPAS) and a side-polished fiber (SPF). The LGA comprises a custom quartz tuning fork (QTF) with 0.8 mm prong spacing, two acoustic micro-resonators (mR) located on either side of the prong spacing, and a single-mode fiber containing a 17 mm polished section passing through both mRs and QTF. The SPF polished face is positioned to enable the evanescent wave (EW) to create a photoacoustic wave and excite the fundamental flexural mode of the QTF. Sensor performance was demonstrated using methane in nitrogen gas mixtures, with CH${}_4$ mixing ratios ranging from 75 ppmv to 1% (by volume), measured with an accumulation time of 300 ms, and a minimum detection limit of 34 ppmv subsequently determined. The EW-QEPAS sensor is ideal for miniaturization, as it does not contain any free-space optics and is suitable for gas sensing in harsh environments and where mobility is required.

我们推出了一种采用石英增强光声光谱 (QEPAS) 和侧面抛光光纤 (SPF) 的全光纤激光气体分析仪 (LGA)。 LGA 包括一个具有 0.8 mm 插脚间距的定制石英音叉 (QTF)、位于插脚间距两侧的两个声学微谐振器 (mR)，以及包含穿过两个 mR 的 17 mm 抛光部分的单模光纤和 QTF。 SPF 抛光面的位置使倏逝波 (EW) 能够产生光声波并激发 QTF 的基本弯曲模式。使用氮气混合物中的甲烷（含 CH）演示了传感器性能${}_4$混合比范围为 75 ppmv 至 1%（按体积计），测量累积时间为 300 ms，随后确定最低检测限为 34 ppmv。 EW-QEPAS 传感器非常适合小型化，因为它不包含任何自由空间光学器件，适用于恶劣环境和需要移动性的气体传感。