基于双可调谐激光器的光纤法布里-珀罗声振动传感解调系统研究

Research of Optical Fiber Fabry-Perot Acoustic Vibration Sensing Demodulation System Based on Dual Tunable Lasers

为实现光纤法布里-珀罗（F-P）腔初始腔长和腔长变化量在宽范围条件下的声振动传感解调,提出了基于双可调谐激光器的正交相位提取方法。理论计算了保持相位正交的光纤F-P腔初始腔长范围。仿真和实验研究了初始腔长漂移对信号解调的影响,实验通过改变温度实现了初始腔长0～2.2μm的漂移,在此情况下对干涉强度法和正交相位提取法解调结果进行了对比分析,正交相位提取法解调信号幅值相对变化小于5.3%,其稳定性比干涉强度法解调信号幅值稳定性提高了12.4倍。利用波长调谐补偿实现了传感器初始腔长范围55～130μm的覆盖,解调信号幅值相对变化小于4.9%。

In order to realize the Fabry-Perot（F-P） acoustic vibration sensing demodulation working under wide range of optical fiber F-P initial cavity length and cavity length shift, a kind of quadrature phase extracting method based on dual tunable lasers is proposed. The range of initial cavity length which keeps quadrature phase is calculated theoretically. The influence of initial cavity length drift on signal demodulation is studied by theoretical simulation and experiment. Initial cavity length drift of 0～2.2 μm is achieved by changing temperature. In this case, interference intensity demodulation method and quadrature phase extracting method are compared and analyzed： relative change of demodulation signal amplitude by quadrature phase extracting method is less than 5.3%; the stability of demodulation signal amplitude by quadrature phase extracting method is 12.4 times as much as that by interference intensity demodulation method. Initial cavity length of 55～130 μm is realized by wavelength tuning compensation and relative change of demodulation signal amplitude is less than 4.9%.