主要研究基于IQ光调制器的16进制正交振幅调制(16-QAM)光发射机中多偏置电压反馈控制性能，着重分析了装置内部两个马赫曾德尔调制器(MZM)的偏置电压与马赫曾德尔干涉仪(MZI)的偏置电压之间的协同控制问题，以及以光发射机的平均输出光功率作为反馈控制两个MZM偏置电压的监测信号所面临的多极值问题。研究证明了当MZM偏置电压处于传输曲线的最低点时监测的输出光功率为极值，且不受MZI偏置电压的影响。分析发现，合适的驱动信号幅度可保证两个MZM偏置电压的反馈控制过程中不存在多局部极值问题。

This paper mainly studies the bias control performance for multiple bias voltages of 16-quadrature amplitude modulation 16-QAM optical transmitter based on IQ optical modulator. The cooperative control of two Mach-Zehnder modulators′ (MZMs′) bias voltages and Mach-Zehnder interferometer′s (MZI′s) bias voltage is analyzed theoretically. Multiple extreme values of the average output optical power as the monitoring signal of feedback control for two MZMs′ bias voltages are also studied by numerical simulation. The results show that the average optical power of 16-QAM optical transmitter is the extreme value when MZMs′ bias voltages are biased at the null transmission points. This conclusion is unaffected by MZI′s bias voltage, and there does not exist the risk of trapping in local extremum if the amplitude of the driver signal is controlled in the proper range.