基于光纤电流传感器的韦尔代常数优化测量法

韦尔代常数(Verdet)是决定光纤电流传感器(FOCT)灵敏度的重要因素之一。根据萨格纳克(Sagnac)干涉原理计算得到校准信号，并测量FOCT的实际输出信号，通过比较这两组信号建立目标函数，基于单纯形算法进行参数优化，从而得到石英光纤的韦尔代常数。实验结果与经典模型计算结果基本吻合。FOCT的输出信号经过测量电路会引入相位差；另外受到调制器和外界环境的影响，干涉回路的工作点会产生漂移，导致输出信号不对称而产生直流量。考虑到以上因素，提出的这种方法还能同时测量出电路的相位差、干涉回路的工作点以及反映非线性畸变的直流量。

Measurement of Verdet Constant in Fiber Optical Current Transducer Using an Optimization Method

Verdet constant is one of important parameters which can determine sensitivity of a fiber optical current transducer (FOCT). Calibration signal is calculated based on Sagnac interference principle, and the output signal of FOCT is measured. By comparing above these two sets of signals, an objective function is established, and then the parameters of the function are optimized based on a Nelder-Mead simplex method. Thereby the Verdet constant of silica fiber is measured. Experimental results are in good agreement with the results calculated by classical models. Phase delay is added to the output signal when it goes through the measuring circuits. Influenced by rotator and changing environment, the working point of the interference loop drifts. As a result, the output signal becomes asymmetric and creates the direct current quantity. Considering all these situations, the phase delay, working point and direct current quantity which reflects the nonlinear distortion can also be obtained by this method.