Wang Heng, Sun Chun, Zhang Xiaoqi, Xu Yufu, Zhao Xinyu, Qi Hongchao, Chen Ke
School of Optoelectronic Engineering and Instrumentation Science, Dalian University of Technology, Dalian, Liaoning 116024, China.
Anal Chem. 2025 Jul 1;97(25):13715-13723. doi: 10.1021/acs.analchem.5c02575. Epub 2025 Jun 16.
An hourglass-shaped resonator based high-sensitivity fiber-optic photoacoustic sensor (FOPAS) for trace gas detection is proposed. To minimize the gas chamber volume of the sensor, the resonance tube is designed with an hourglass-shaped structure. In order to match the paths of multiple light reflections with the hourglass-shaped structure, a 4 focusing optical system is implemented to establish a multipass cell (MPC). This configuration significantly reduces the resonator volume while maintaining the multiple reflection conditions, thereby enhancing the photoacoustic signal. The light undergoes 52 reflections within the MPC and converges to a single point at the center of the resonance tube, achieving an optical path length of 5.2 m. The acoustic pressure signal generated in the sensor is detected using a highly sensitive fiber-optic Fabry-Perot (FP) cantilever microphone. The amplitude of the photoacoustic signal of the hourglass-shaped resonance tube is 2.7 times that of the cylindrical resonance tube. The amplitude of the photoacoustic signal after multiple reflections is 18 times that of a single reflection. The designed FOPAS achieves a minimum detection limit (MDL) of 1.4 ppb (1σ @100 s), and a normalized noise equivalent absorption (NNEA) coefficient of 3.6 × 10 W cm Hz for CH detection.
提出了一种基于沙漏形谐振器的用于痕量气体检测的高灵敏度光纤光声传感器（FOPAS）。为了使传感器的气室体积最小化，谐振管设计为沙漏形结构。为了使多次光反射路径与沙漏形结构相匹配，采用了一个4聚焦光学系统来建立多程池（MPC）。这种配置在保持多次反射条件的同时显著减小了谐振器体积，从而增强了光声信号。光在MPC内经历52次反射并在谐振管中心汇聚到一个点，实现了5.2 m的光程长度。传感器中产生的声压信号使用高灵敏度光纤法布里 - 珀罗（FP）悬臂式麦克风进行检测。沙漏形谐振管的光声信号幅度是圆柱形谐振管的2.7倍。多次反射后的光声信号幅度是单次反射的18倍。所设计的FOPAS实现了1.4 ppb（1σ @100 s）的最低检测限（MDL）以及用于CH检测的3.6×10 W cm Hz的归一化噪声等效吸收（NNEA）系数。
