为了保持电光调制器(EOM)输入光偏振方向始终与其内部可传播模式偏振方向一致，使EOM获得良好的调制效果，提出了一种基于比例-积分-微分(PID)算法的EOM自适应偏振控制方法，理论分析并实验验证了该方法的可行性。实验结果表明，基于该方法设计的控制系统不仅能实时监测EOM输出光功率，而且能保持其输出光功率最大；与激光器和EOM输入端直接用保偏光纤连接时相比，PID偏振控制下EOM输出平均功率提高了3.08 dB，PD输出电压标准差由0.121 4降至1.237 5×10^-4，稳定控制状态下偏振态矫正时间在ms量级。

In order to keep the input light polarization direction of electro-optic modulator(EOM) up with that of internal propagation mode in an EOM, and to obtain expected modulation effect, an adaptive control method based on proportional-integral-derivative(PID) algorithm was proposed. Theoretical analysis and experimental demonstration was conducted to verify the feasibility of the proposed method. The experimental results show that the control system designed by the method not only can real-time monitor the output optical power of EOM, but also can keep the output power maximum. Compared with the performance of EOM conncted directly to a narrow band laser with a polarization maintaining fiber, the output average power of EOM under the polarization control based on PID is increased by 3.08 dB and the standard deviation of PD output voltage is reduced from 0.121 4 to 1.237 5×10^-4. And the correction time for the state of polarization is in the order of ms when the system is working in stable control state.