布里渊光时域反射计中电光调制器的调制特性与控制

Modulation performance and control of electro-optic modulator for the distributed Brillouin sensing system

在布里渊光时域反射计(BOTDR)中,电光调制器(EOM)的工作点会随着外部环境变化而发生漂移,这将影响BOTDR系统的测量精度及测量稳定性。本文在分析BOTDR系统中EOM调制特性的基础上,提出了一种控制EOM工作点的方法,使用数字信号处理器作为控制核心,采用"步进跟随"的算法。实验结果表明,本文方法可以使EOM长期稳定在高微波调制效率的工作点上。将这种方法应用于BOTDR系统中,可以使BOTDR系统的测量精度以及测量稳定性得到提升。

In a Brillouin optical-fiber time-domain reflectometry（BOTDR） system,it is convenient to obtain the Brillouin signal by coherent detection,which needs an electro-optic modulator（EOM） to shift the frequency of the reference signal.However the bias point of the（EOM） may slowly change due to many external factors,which leads to the instability of the modulation efficiency.In this paper,a novel and simplified stabilization technique based on digital signal processor and step-by-step tracking algorithm is proposed.Experimental results show that the EOM′s bias point can be locked quite well in 24 h and the accuracy and the stabilization of the sensing system can be improved obviously.