针对双平行马赫-曾德尔调制器工作点漂移的问题, 提出一种适用于16进制正交幅度调制的双平行马赫-曾德尔调制器自动偏压控制算法。算法分为两个部分, 初始化部分和跟踪锁定部分。初始化部分的目的是找到一个接近偏置电压的工作点, 以减少跟踪锁定部分算法锁定工作点需要花费的时间; 跟踪锁定部分使用抖动信号检测法找到精确工作偏置点, 并且能实时地跟踪随环境变化的偏置点, 使得偏置电压在尽量长时间内处于最佳偏置点附近, 且在最佳偏置点附近游走的范围尽量小。通过实验分析了影响算法结果的因素。实测数据表明, 此算法能在较短时间内找到双平行马赫-曾德尔调制器最佳工作偏置点, 并能实时进行跟踪调整。

This paper proposes an automatic bias control algorithm for dual parallel Mach-Zehnder modulator which is proposed for 16 Quadrature Amplitude Modulation (16QAM) formats to solve the working points drifting problem in dual parallel Mach-Zehnder modulators . The algorithm is divided into two parts, which are initialization part and tracking locking part. The purpose of the initialization part is to find a working point close to the bias voltage to reduce the time required to lock the working point in the tracking locking algorithm. The tracking and locking parts use the detection method of dithering signal to find accurate working bias point, and track the offset point varying in real time. Therefore, the bias voltage can always stay at the best bias point with small the range of variation. The factors that affect the results of the algorithm are analyzed in the experiment verification. The measured data show that this algorithm can find the best working bias point of dual parallel Mach-Zehnder modulator in a relatively fast time. It also shows the ability to track and adjust the working bias point in real time.