超弱反射光栅准分布式光纤传感系统研究

Study of a Quasi-Distributed Optical Fiber Sensing System Based on Ultra-Weak Fiber Bragg Gratings

采用波长可调谐光源与光时域反射技术(OTDR)结合的方案,通过对光脉冲调制技术和光电转换电路的优化,实现了一种对超弱全同反射光纤光栅的准分布式解调系统。实验中,20个中心波长相近的超弱反射光栅间隔2m放置于约5.8km长的光纤尾端,该解调系统成功实现了对这些反射率仅为0.01%的超弱反射光栅高信噪比的解调与定位,并且测得的光纤布拉格光栅(FBG)中心波长随温度变化的线性度达到99.7%以上。

A quasi-distributed fiber Bragg grating （FBG） demodulating system is developed by combining the wavelength tunable laser and the optical time domain reflectometry （OTDR） technique. By optimizing the optical pulse modulation and the light detection circuit, the ultra-weak reflective FBGs can be demodulated and located. In the experiment, 20 ultra-weak reflective FBGs of only 0.01% reflection with the interval space of 2 m are connected to the end of a 5. 8 km long fiber. All the central wavelength and position of the FBGs can be measured simultaneously. The measured FBG center wavelength has a good linearity of 99.7 %.