中文摘要：

报道了一种基于掺铒光纤激光器瞬态特性的新型气体浓度传感器．用光纤环全反镜和光纤Bragg光栅（FBG）构成F-P线形腔，通过调节光栅的反射波长，使激光激射波长落在C2H2的一个较强的吸收峰1531．56nm．激光激射延迟时间与激光器谐振腔损耗密切相关，气体浓度的改变将引起谐振腔损耗的改变，通过测量激光激射延迟时间可以获得气体的浓度．该装置分辨率及灵敏度由抽运光脉冲的高功率电平和低功率电平决定，传感器的动态测量范围由抽运光高功率电平决定．当高功率和低功率电平分别为25mW和5．9mW时，该传感器的灵敏度和分辨率分别为100ppm／μs和20ppm．

英文摘要：

A novel fiber sensor for measuring gas concentration is reported, which is based on the transient regime of a Er-doped fiber laser. A Sagnac fiber loop and a FBG that also acts as the sensing element form the linear fiber laser cavity. By adjusting the central wavelength of the grating mirror, the oscillating wavelength is set to 1531.56 nm, which is a strong absorption peakof C2H2. The gas concentration can be obtained by measuring the laser build-up time, which is closely related with the cavity loss and therefore determined by the gas concentration, in the present experiment, the sensor＇ s sensitivity and resolution can be adjusted simply by controlling the pumping level. When the pump pulse is at high level and low level of 25 mW and 5.9 mW, respectively, a sensitivity of 100 ppm/μs and resolution of 20 ppm are achieved.