Study on Fiber Methane Sensing System Using FBG Filters

差分吸收法是进行瓦斯远距离监测的重要方法，根据瓦斯在近红外波段的吸收特性，报道了一种新型的远距离光纤瓦斯传感系统。采用1．3μm超辐射发光二极管为光源，利用光纤布拉格光栅(FBG)优良的窄带滤波特性实现了对瓦斯的差分吸收测量。和传统的干涉滤光片相比，光纤光栅滤波器插入损耗低、制备简单。系统具有全光纤化、结构简单、工作距离远、稳定性好的特点。工作距离10km，测量灵敏度为0．1％，是瓦斯爆炸极限的2％。Differential absorption method is an important method for methane remote monitoring. Based on the methane absorption spectrum in near-infrared region, a novel kind of fiber remote sensing system utilizing fiber Bragg grating (FBG) filters and 1.31 μm superradiance light-emitting diode (SLED) was developed for real time absorption measurement. The highly sensitive technique was achieved employing the two-wavelength differential absorption method. FBG has low insert loss and can be produced easily compared with dielectric interference filters. This system has a number of advantages such as all-fiber sensor, high sensibility, simply construct and long-distance measurement. The measurement sensitivity is 0.1％. It is 2% of the lower explosion limit of methane density in air