中文摘要：

研制了基于可调谐掺Er光纤激光器的共振式光声光谱乙炔气体检测系统，结合波长调制和锁相放大器的二次谐波信号检测技术，有效地消除了光声池窗片和池壁吸收入射光而引起的背景噪声，通过对该系统的光学、声学和电子检测系统的优化，实现了低浓度乙炔气体的流动式检测。实验结果证明，当气体浓度较低时，二次谐波振幅与气体浓度成正比，其线性响应相关度达到0．99953。在常温常压和3．5mW平均光功率以及100ms锁相积分时间条件下，乙炔气体的极限检测灵敏度达到了0．3ppm（1ppm=1μg·mL^-1）（SNR=1时），系统用可调谐掺Er光纤激光器代替半导体激光器作光源，降低了成本，为发展低成本、实用、便携式微量气体光谱检测仪器奠定了基础。若采用多光程光声池，或者采用EDFA提高激光功率，叮大幅度提高信噪比，将极限检测灵敏度提高至ppb（1ppb=1ng·mL^-1）量级。

英文摘要：

An acetylene detection system has been constructed with a tunable erbium-doped fiber laser （TEDFL） based photoacoustic spectrometer. Combining wavelength modulation and second harmonic signal detection technique, the system is able to effectively eliminate the background noise generated by absorption of the cell windows and the wall of the acoustic resonator. The system was applied to low concentration acetylene flowing measurement, through optimizing the systemic optics, acoustics and electron detection technique condition. The experimental results show that the second harmonic amplitude is directly proportional to gas concentration. Their linear pertinence coefficient is 0. 999 53. The system sensitivity limit for acetylene detection is 0. 3 ppm under atmosphere pressure with 100 ms time constant and 3. 5 mW average optical power. The TEDFL was used as light source in stead of the DFB diode laser which is relatively costly. The system appears promising as a basis for developing cheap, practical, portable spectroscopy instruments for trace gas detection. The detection sensitivity could be greatly improved by using multi-path cell or increasing the laser power with EDFA.