提出并实现了一种基于光纤光栅(FBG)激光器的高分辨率光纤传感系统。通过在一段高增益有源光纤写入光纤光栅形成光纤激光传感器, 待测信号作用在激光器上引起激光频率变化, 采用偏振无关的非平衡迈克耳孙光纤干涉仪将激光频率变化转化为干涉仪相位变化。干涉仪输出的信号经过光电转换后, 用采集卡转换为数字信号输入计算机, 最后利用改进的归一化相位载波(PGC)解调技术, 实现信号的高分辨率解调。实验表明该传感系统的动态应变分辨率达到了5.6×10-4 nε/Hz, 并且解调结果与待测信号具有良好的线性关系。

A high-resolution fiber sensor system based on fiber Bragg grating (FBG) laser is proposed and demonstrated. The fiber laser sensor is made by writing Bragg grating into a section of high gain active fiber. Unmeasured singals applied on the fiber laser induce laser frequency shifts. And a polarization-insensitive unbalanced Michelson fiber interferometer is employed to transpose the frequency shifts into phase shifts of the interferometer. After converting the output singals of the interferometer to electric signals, the signals are sampled and input into the computer. An improved normalized phase generated carrier (PGC) demodulation technique is used to achieve high resolution demodulation. Experiments demonstrate that the dynamic stain resolution of this system is 5.6×10-4 nε/Hz, and the system output is linear to the strain of the fiber laser sensor.