介绍了一种应用于光纤时频传递秒脉冲信号(1PPS)调制的马赫-曾德尔调制器(MZM)偏置点反馈控制系统。本系统将电光调制器的偏置点设置在传输曲线的最小值点(Null)和正斜率正交点(Quad+)之间的线性区域,利用光电二极管(PIN)探测输出1PPS信号的低电平电压的波动来检测偏置点的漂移。对测量到的电压信号进行数字处理后通过控制偏置点反馈系统来稳定调制器的偏置点。对反馈控制理论进行了原理推导,并与基于微扰理论的商用偏置点稳定系统进行了对比实验。实验证明该系统可以避免微扰信号对1PPS传输稳定性的影响,传递性能优于商用偏置点稳定系统。实验结果表明,1PPS传递时延波动的峰峰值为174 ps,均方根值(RMS)为18 ps,在平均时间为104s时,1PPS的时间阿伦方差(TDEV)下降到1.7 ps。 A Mach-Zehnder modulator (MZM) bias point feedback control system for fiber-optic time-frequency transmission of second pulse signal (1PPS) is introduced. In this system, the bias point of the electro-optic modulator is set in the linear region between the minimum point (Null) and the quadrature point (Quad +) of the transmission curve. The low voltage of the output 1PPS signal is detected by a photodiode (PIN) The fluctuation of the bias point to detect drift. The measured voltage signal is digitally processed and the bias point of the modulator is stabilized by controlling the bias point feedback system. The principle of the feedback control theory is deduced and compared with the commercial bias stability system based on the perturbation theory. Experiments show that the system can avoid the influence of the perturbation signal on the transmission stability of 1PPS, and the transmission performance is superior to the commercial bias point stabilization system. The experimental results show that the peak-to-peak value of 1PPS propagation delay is 174 ps and the root mean square (RMS) is 18 ps. The 1PPS time-dependent Allan variance (TDEV) drops to 1.7 ps at 104s.