中国激光, 2015, 42 (9): 0905002, 网络出版: 2015-09-06
应用于秒脉冲传递的电光调制器反馈控制系统
Feedback Control System of Electro-Optic Modulator Used for Transferring One Pulse per Second
光纤光学 偏置点控制 马赫-曾德尔调制器 秒脉冲 时频传递 fiber optics bias point control Mach-Zehnder modulator one pulse per second time and frequency transfer
摘要
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104 s时,1PPS的时间阿伦方差(TDEV)下降到1.7 ps。
Abstract
A bias point feedback control system of Mach-Zehnder modulator (MZM) for transferring one pulse per second (1PPS) is used in time and frequency transfer via optical fiber. The low-level voltage of the 1PPS output by photodiode is used to measure the drift of the bias point, which is set between minimum point (Null) and orthogonal point of positive slope (Quad+) on transmission curve. The measured signal is digitally processed and used to control the feedback system to stabilize the bias point. The theoretical derivation of the principle is described and the performance of the system is compared with that of commercial bias point stabilized system based on dither method. The experimental results show that the behavior of our system is better, and the instability results from the dither can be avoided. The peak-peak fluctuated value of the propagation delay of the 1PPS is 174 ps, and the root-mean-square (RMS) value is 18 ps. The time deviation (TDEV) of the 1PPS for the averaging time of 104 s decreases to 1.7 ps.
程楠, 陈炜, 刘琴, 徐丹, 杨飞, 桂有珍, 蔡海文. 应用于秒脉冲传递的电光调制器反馈控制系统[J]. 中国激光, 2015, 42(9): 0905002. Cheng Nan, Chen Wei, Liu Qin, Xu Dan, Yang Fei, Gui Youzhen, Cai Haiwen. Feedback Control System of Electro-Optic Modulator Used for Transferring One Pulse per Second[J]. Chinese Journal of Lasers, 2015, 42(9): 0905002.