高分辨率光纤激光振动传感器研究

Study on fiber laser vibration sensor with high resolution

提出并实现了一种高分辨率光纤激光振动传感器。通过在一段高增益有源光纤上写入光纤Bragg光栅(FBG),激光泵浦后形成光纤激光器,振动信号引起激光器的波长发生变化,采用偏振无关的非平衡Michelson干涉仪将激光波长变化转换为相位变化。干涉仪输出的信号经过光电转换后,使用采集卡转换为数字信号输入计算机,采用相位载波(PGC)解调技术,实现信号的高分辨率解调。试验结果显示:该传感器系统的最小可探测加速度在250 Hz时为200 ngn/Hz,解调结果与待测信号具有良好的线性关系。

A fiber lasers vibration sensor with high resulution is propoced and realized. The fiber laser sensor is made by writing Bragg grating into a section of high gain active fiber. Vibration signal applied on the fiber laser induces laser frequency shifts, and a polarization-insensitive unbalanced Michelson fiber interferometer is employed to transform the frequency shifts into phase shifts of the interferometer. After converting the output of the interferometer to electric signals, the signals are sampled and inputted into the computer, an phase generated carrier（ PGC ） demodulation technique is used to achieve high resolution interrogation. The experiment result demonstrates that the minimal detectable acceleration of this system is 200 ngn//Hz at 250 Hz, the result demonstrates the linear relationship between the acceleration and the wavelength shifts of FLS.