Wang Heng, Zhang Jingya, Sun Chun, Zhao Xinyu, Qi Hongchao, Chen Ke
School of Optoelectronic Engineering and Instrumentation Science, Dalian University of Technology, Dalian, Liaoning 116024, China.
School of Dalian University of Technology and Belarusian State University Joint Institute, Dalian University of Technology, Dalian, Liaoning 116024, China.
Anal Chem. 2025 Apr 15;97(14):8120-8128. doi: 10.1021/acs.analchem.5c01233. Epub 2025 Apr 3.
A high-sensitivity fiber-optic photoacoustic carbon monoxide (CO) sensor based on quantum cascade laser (QCL) and nonresonant multipass cell is proposed. By leveraging the mid-infrared fundamental band absorption, multipass absorption enhancement, and cantilever resonance frequency detection, a multimechanism synergy has been achieved to enable highly sensitive detection of CO. In the mid-infrared band, CO exhibits a strong absorption coefficient, thereby eliminating the need for a high-power optical amplifier. Furthermore, by integrating a miniaturized multipass cell, the photoacoustic signal is remarkably enhanced, enabling the miniaturization and ultrahigh sensitivity of the sensor. A pair of spherical reflectors are symmetrically installed at both ends of the photoacoustic cell to form a Herriott multipass cell. The light beam reflects 20 times within the multipass cell, creating 10 elliptically distributed light spots. The gas chamber volume of the sensor is only 1.28 mL, with an optical path length of 510 mm. The generated photoacoustic signals are measured by a fiber-optic Fabry-Perot (FP) cantilever microphone, which can detect weak signals with high sensitivity at the resonance frequency of the cantilever. The measured signal amplitude is 8.7 times that of a single reflection. When the averaging time is 100 s, the minimum detection limit of the system for CO is 0.8 ppb, corresponding to a normalized noise equivalent absorption (NNEA) coefficient of 4.94 × 10 Wcm/Hz.
提出了一种基于量子级联激光器（QCL）和非共振多程池的高灵敏度光纤光声一氧化碳（CO）传感器。通过利用中红外基频带吸收、多程吸收增强和悬臂共振频率检测，实现了多机制协同作用，以实现对CO的高灵敏度检测。在中红外波段，CO表现出很强的吸收系数，从而无需高功率光放大器。此外，通过集成小型化多程池，光声信号得到显著增强，实现了传感器的小型化和超高灵敏度。一对球面反射镜对称安装在光声池两端，形成赫里奥特多程池。光束在多程池内反射20次，产生10个椭圆分布的光斑。该传感器的气室体积仅为1.28 mL，光程长度为510 mm。产生的光声信号由光纤法布里-珀罗（FP）悬臂式麦克风测量，该麦克风可以在悬臂的共振频率下高灵敏度地检测微弱信号。测量的信号幅度是单次反射的8.7倍。当平均时间为100 s时，该系统对CO的最低检测限为0.8 ppb，对应归一化噪声等效吸收（NNEA）系数为4.94×10 Wcm/Hz。
