干涉型光纤传感器相位漂移的无源解决方法

A Passive Method for Resolving Phase Shifting of Interferometric Fiber-Optic Sensors

相位漂移是干涉型光纤传感器实际应用中遇到的关键问题之一。提出了一种基于线性控制原理的无源解决方法,利用干涉仪的输出信号得到一个误差信号对光源波长进行调节,在非平衡干涉仪中产生一个补偿相位,对各种噪声引起的相位漂移进行补偿,从而使干涉仪一直工作在最灵敏的地方,实现了无源线性检测。搭建实验系统,利用该方法对某一干涉型光纤水听器进行了测试,结果表明该光纤水听器被很好地控制在正交工作状态,获得了稳定的输出信号。在20~2500 Hz频率范围内,该光纤水听器的声压灵敏度为-156.5 dB（0 dB=1 rad/μPa）,频响波动〈±1.2 dB,与采用相位载波（PGC）调制解调方法测得的结果一致,从而验证了该方法的可行性。

Phase shifting is one of the key problems in the application of interferometric fiber-optic sensors. A passive method for resolving the phase shifting was proposed based on the theory of linear control. An error signal obtained from the output of the interferometer was added to the laser. Then a compensating phase was generated in an unbalanced interferometer due to the wavelength change of the laser. The phase shifting induced by all kinds of noises was compensated. And the interferometer was locked with the maximum sensitivity. The passive linear detectionis realized. A test system was set up, and an interferometric fiber-optic hydrophone was tested and found to work at the orthogonal state. The output of the fiber-optic hydrophone was stabilized. The average acoustic pressure sensitivity is -156.5 dB （0 dB= 1 rad/μPa） over the frequency range of 20 Hz to 2500 Hz, and the frequency fluctuation is less than ±1.2 dB, which accords well with the results obtained with the method of phase generated carrier （PGC） modulation and demodulation. The experimental results have proved the feasibility of this method.