为实现马赫曾德尔(MZ)电光强度调制器(EOIM)工作点的实时控制，提出一种基于虚拟仪器技术的工作点自动控制方案。采用闭环反馈控制系统，引入微扰动信号，通过“扫描—鉴相补偿”的方法,可以使自动控制工作点长时间锁定于传输曲线的最低点。当激光器输出功率为6 mW，控制EOIM在1 h内稳定于最低点，实验测得EOIM输出平均光功率1.198 μW，标准差0.123 μW，波动小于0.43 μW；在EOIM最低点外加电脉冲信号进行调制时，产生消光比均值达25.71 dB的光脉冲。输出脉冲消光比与未加控制时相比提高9.94 dB，波动小于0.5 dB，大大提高了MZ电光调制器的工作稳定性。

A practical method based on virtual instrument technique in order to realize operating points automatic control for Mach-Zehnder (MZ) electro-optic intensity modulators (EOIM) is propsed. Operating point at the minimum of the transmission curve can be automatically controlled steadily by means of “sweep—phase discrimination and compensation” in a closed loop feedback system. When the output power of the laser is 6 mW, EOIM is controlled steadily at minimum point for an hour. The average optical output power of the EOIM is 1.198 μW, standard deviation is 0.123 μW and fluctuation is less than 0.43 μW at minimum point with control. When the additional electronic pulse signal is modulated at minimum point of EOIM, light pulse with mean extinction ratio (ER) of 25.71 dB is produced. Under pulse modulation, the output pulse ER is 9.94 dB higher than that in the condition without control, and fluctuation is less than 0.5 dB/h. Which improves working stability of MZ electro-optic modulator greatly.