中文摘要：

由于工业监控和环境检测的需要,甲烷气体检测日益得到人们的关注。研究了基于中红外分布反馈量子级联激光器（DFB-QCL）的光声光谱技术,并应用于痕量甲烷的检测。自主研发的DFB-QCL室温工作时的激射波长在7.6μm附近,覆盖了甲烷的特征吸收谱线1 316.83cm-1。待测甲烷气体充入亥姆霍兹光声谐振腔中,DFB-QCL的工作频率为234Hz、室温脉冲工作时峰值功率为80mW。中红外光经过甲烷吸收后,产生的声波信号经麦克风检测,由锁相放大器对信号进行采集并输入计算机进行处理。按信噪比为1计算,得到甲烷的探测极限为189nmol.mol-1。

英文摘要：

There have been considerable interests in methane detection based on infrared absorption spectroscopy for industrial and environment monitoring.The authors report on the realization of photoacoustic detection of methane（CH4） using mid-infrared distributed-feedback quantum cascade laser（DFB-QCL）.The absorption line at 1 316.83 cm-1 was selected for CH4 detection,which can be reached by the self-manufactured DFB-QCL source operating in pulsed mode near 7.6 μm at room-temperature.The CH4 gas is filled to a Helmholtz resonant photoacoustic cell,which was equipped with a commercial electret microphone.The DFB-QCL was operated at 234 Hz with an 80 mW optical peak power.A detection limit of 189 parts per billion in volume was derived when the signal-to-noise ratio equaled 1.