在传统LiNbO3马赫曾德尔调制器偏置控制理论的基础上，提出了一种基于快速傅里叶变换(FFT)算法和低频小信号扰动的谐波响应反馈控制方法，实现了一种与调制器输入光功率及插入损耗无关、任意工作点可偏置并锁定的精密光电控制系统。利用比例积分微分（PID）控制方法，实现了任意工作点偏移小于0.5°的控制精度，实验结果亦证明该控制系统能够实现强度调制器任意工作点的偏置及锁定。这些结果对于将LiNbO3强度调制器稳定在最佳工作点并实现高速长距光纤通信系统是很有帮助的。

After comparing the traditional LiNbO3 Mach-Zehnder electro-optic modulator bias control techniques, a novel bias control method based on fast Fourier transformation (FFT) algorithm and the harmonic response feedback of a low frequency dither tone is proposed. Using this technique, a precise optoelectronics bias control system is realized to lock the modulator at an arbitrary point within its transfer function. This bias control technique is found to be independent on the optical input power and the insertion loss of modulator. Moreover, the proportion integration differention (PID) control method is used to optimize parameters and achieve a locking accuracy better than 0.5°. In addition, this bias control system is also verified experimentally to set and lock the modulator at an arbitrary bias point. Those results are helpful to stabilize the LiNbO3 Mach-Zehnder modulator at the optimal operating point and achieve an ultra-high speed, long haul optical fiber communication system.