马赫-曾德尔电光调制器多工作点偏压控制技术

A novel circuit design for bias controlling of Mach-Zehnder elec tro-optic modulator

马赫-曾德尔电光调制器(EOM)由于其自身结构因素的制约,容易受到自身温度变化和外界环境的干扰,导致其工作性能不稳定。本文提出并实现了一种基于检测工作点斜率的马赫-曾德尔EOM自动偏压控制方案。首先输入一微扰信号,然后通过检测调制信号的工作点斜率判断EOM工作点的漂移方向和漂移量,并最终调节偏置电压使EOM稳定工作。本文方案不仅可控制EOM工作在其传输特性曲线的任一位置,而且避免了光源本身功率不稳定对偏压调节的影响。实验表明,当该电路用于脉冲调制控制时,电光调制器消光比的上下浮动小于等于0.26dB,大大提高了EOM的工作稳定性。

Mach-Zehnder electro-optic modulators （EOMs） with parallel arms are easy to be affected by the temperature change and other environmental factors, which results in unstable performance of the modulator. In this manuscript,we propose a novel method for automatic bias voltage controlling of the modulator. A small sine voltage signal is first input to the modulator as a disturbing~ signal. Then, by mo- nitoring the slope change of the output signal, the drift direction and quantity of the working point can be quickly determined. The designed circuit is used for demonstration in the pulse modulations. Our experi- ments show that the fluctuation of extinction ratio （ER） of the modulated signal can be controlled within 0. 26 dB. This proposed method can also be applied to lock modulators working at any point of their transfer curves and cancel out the instability of the input light power.