The Design Of FPGA-based MZ Electro-Optic Modulator Bias Control System

Optical fiber communication becomes an important part of communication field because of its incomparable advantages.With the development of optical fiber communication technology,its status is also rising.The realization of optical fiber communication relies on the support of many technologies,and one of them is the properties of the electro-optic modulator,and how to control the electro-optic modulator working in ideal working point is the content of this article.This paper studies the MZ electro-optic modulator which is widely used in optical fiber communication field,and design a system which can control the modulator working in the ideal working point.At present,the research of bias voltage control system could be divided into two categories: one is based on analog signal and the other is based on digital signal.The digital system has a better performance than the analog system in anti-disturbance,processing speed,processing precision,and etc,so in this paper,the FPGA is used as the core processing component to build a digital system for the bias voltage control of MZ electro-optic modulator.In this paper,the design of the bias voltage control system mainly includes two aspects.Firstly,according to the basic principle of bias voltage control,we need to choose appropriate devices,including the FPGA chip and the other peripheral chips,and then build the hardware circuit which can complete the control task;Secondly,we need to write the control program with the corresponding hardware description language.According to the experimental results,the control board could successfully control the bias voltage of MZ electro-optic modulator.Compared with the other control boards,this design shows the advantage of high precision and fast speed;The feedback signal is processed in FPGA,so it is convenient to modify the control strategy;The construction of the feedback signal of this project makes the working point of the MZ electro-optical modulator keep stable with the change of input light intensity.