1/4波片是全光纤电流传感器 (AFOCT)最重要的光学器件之一，针对 SLD宽谱光源产生的时间相干性问题，借助琼斯矩阵对光束的传播全过程进行了详细分析与计算，推导出探测器关于 1/4波片参数的光强表达式。根据闭环电路工作原理得到了 1/4波片参数对传感器信噪比和标度因数的影响规律，并通过实验验证。根据传感光纤的 Verdet(维尔德 )常数的温度特性，提出了 1/4波片的优化设计。

The quarter-waveplate is one of the most important optical devices in all fiber optical current transducer (AFOCT). Taking into account the temporal coherence of SLD, the detailed analysis and calculation of the entire spreading process of the beam are completed by using Jones Matrix. The expression of optical inten? sity depending on the parameters of the quarter-waveplate can be set up. According to the principle of closed-loop circuit, the law about quarter-waveplate affecting the signal-to-noise ratio (SNR) and scale factor of AFOCT is disclosed and verified by experiments. Optimum design of the quarter-waveplate which is based on the temperature characteristic of the Verdet constant is also shown.