光通信系统的偏振复用和偏振控制技术

发布时间：2019-06-09 11:44

【摘要】：随着光通信技术的迅猛发展，偏振在光纤中的作用也越来越重要。首先，偏振复用技术通过在正交的偏振态上加载不同的调制信号可以非常容易地实现信道容量的加倍。其次，偏振模色散(PMD)等与偏振相关的问题也会在很大程度上影响高速光通信系统的性能。最后，随着相干探测的发展，对偏振态的追踪也显得尤为重要。这样在高速光通信系统内偏振控制器就显得十分重要。本论文主要包括两项内容：其一，研究了高速偏振复用系统的实现，通过复用IQ调制器输出的25Gbits/s信号实现了50Gbit/s信号的复用输出并测试了20km传输后的情况。其二，以Altera公司Cyclone IV系列FPGA芯片为主控芯片设计了铌酸锂(Lithiumniobate)晶体型偏振控制器的驱动电路。根据系统要求，选择了高速的数模转换器和模数转换器，并设计了相应的匹配电路。本设计完成了硬件电路的原理图和PCB设计，完成了相关软件代码的编写，并在此基础完成了相关的测试工作。系统的有效分辨率不低于11位，，可以实现不低于0.1rad的分辨精度。对于较高的驱动电压采用电流反馈型运算放大器来实现对高速的模数转换器输出信号的放大，对大于10MHz的信号输入信号可以实现大于13dB的放大。当对较低频率信号放大时可以达到不小于33dB的增益，完全胜任偏振控制器的驱动控制工作。本论文还对几种常用的实现偏振控制的方式进行了分析，并在此基础上设计了系统的软件程序，在高增益放大输出的情况下偏振控制时间不大于6ms，有效追踪速度不小于600rad/s。
[Abstract]:With the rapid development of optical communication technology, polarization plays a more and more important role in optical fiber. Firstly, polarization multiplex technology can easily double the channel capacity by loading different modulation signals on the orthogonal polarization state. Secondly, polarization-related problems such as polarization mode dispersion (PMD) will also affect the performance of high-speed optical communication systems to a great extent. Finally, with the development of coherent detection, the tracking of polarization states is particularly important. In this way, polarization controller is very important in high speed optical communication system. This paper mainly includes two contents: first, the implementation of high-speed polarization reuse system is studied. The multiplex output of 50Gbit/s signal is realized by multiplex the 25Gbits/s signal output from IQ modulator, and the situation after 20km transmission is tested. Secondly, the driving circuit of lithium niobate (Lithiumniobate) crystal polarization controller is designed by using Cyclone IV series FPGA chip of Altera company as the main control chip. According to the requirements of the system, the high-speed digital-to-analog converter and analog-to-digital converter are selected, and the corresponding matching circuit is designed. This design completes the schematic diagram of the hardware circuit and the PCB design, completes the related software code writing, and completes the related test work on this basis. The effective resolution of the system is not less than 11 bits, and the resolution accuracy of the system is not lower than that of 0.1rad. For the higher driving voltage, the current feedback operational amplifier is used to amplify the output signal of the high speed analog-to-digital converter, and the input signal of the signal larger than 10MHz can be amplified larger than 13dB. When the low frequency signal is amplified, the gain of not less than 33dB can be achieved, and it is fully competent for the drive control of polarization controller. In this paper, several commonly used ways to realize polarization control are analyzed, and the software program of the system is designed on the basis of which the polarization control time is not more than 6 Ms in the case of high gain amplification output. The effective tracking speed is not less than 600 rad / s.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN929.1

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