提出一种珐珀解调, 适用于开放环境的全光式石英增强光声光谱气体探测系统。 基于石英增强光声光谱系统, 采用法珀干涉解调代替传统的电解调方式, 通过拾取石英音叉的叉指侧面与光纤端面之间形成的法珀腔的腔长变化解调得到被测气体的光声光谱信号。 构建了实验系统, 在开放环境中完成了对空气中水蒸气的探测实验, 得到其归一化噪声等效吸收系数为2.80×10-7 cm-1·W·Hz-1/2。 结果表明, 该探测系统的探测灵敏度是传统石英增强光声光谱探测系统的2.6倍。 该系统具有极强的抗电磁干扰能力、 能够用于易燃易爆气体检测、 适用于高温、 高湿度等恶劣环境并实现远距离多点、 组网探测。

An all-optical quartz-enhanced photoacoustic spectroscopy system, based on the F-P demodulation, for trace gas detection in the open environment was proposed. In quartz-enhanced photoacoustic spectroscopy (QEPAS), an optical fiber Fabry-Perot method was used to replace the conventional electronic demodulation method. The photoacoustic signal was obtained by demodulating the variation of the Fabry-Perot cavity between the quartz tuning fork side and the fiber face. An experimental system was setup. The experiment for detection of water vapour in the open environment was carried on. A normalized noise equivalent absorption coefficient of 2.80×10-7 cm-1·W·Hz-1/2 was achieved. The result demonstrated that the sensitivity of the all-optical quartz-enhanced photoacoustic spectroscopy system is about 2.6 times higher than that of the conventional QEPAS system. The all-optical quartz-enhanced photoacoustic spectroscopy system is immune to electromagnetic interference, safe in flammable and explosive gas detection, suitable for high temperature and high humidity environments and realizable for long distance, multi-point and network sensing.