奇点光束在光纤通信中的基础与应用研究

发布时间：2018-05-25 22:08

本文选题：奇点光束 + 轨道角动量光束　；参考：《深圳大学》2017年硕士论文

【摘要】：目前信息社会已全面进入互联网时代,互联网的飞速发展对光纤通信带宽需求不断增长。一方面,现有光纤通信的频谱带宽资源已接近饱和。另一方面,随着各种复用技术不断突破,光纤通信系统容量剧增,但现有通信单模光纤的单信道通信容量已接近香农极限。所以为满足今后光纤通信的带宽需求,亟需寻找新的光束复用技术和大容量复用光纤。奇点光束是指基于位相奇点的轨道角动量(OAM)光束和偏振奇点的柱矢量(CVB)光束,它们为光束的复用提供了一种全新的自由度。但奇点光束在自由空间中传输容易受到大气扰动和热湍流的影响,导致传输的奇点光束模式纯度较低而发生模式串扰。由奇点光束携带通信信号,在自由空间光通信系统中可能发生信号的畸变,最终会导致在解调端信号无法解调。而光纤则为奇点光束的稳定传输提供了条件。本论文提出将OAM和CVB光束的复用和解复用技术应用于光纤通信中,并对OAM和CVB光束在光纤中的传输进行基础与应用研究,为现代光纤通信的发展提供一种全新技术手段和思路。本论文的主要研究内容和成果如下:(1)演示一种柚子型微结构光纤(MOF)中OAM光束的传输。首先使用有限元软件计算柚子型微结构光纤所支持的各种本征矢量模式,运用模式叠加理论计算这些光纤本征矢量模式所能形成的OAM模式,各个本征矢量模式之间的有效折射率差达到10~(-2)以上,理论上可以有效减弱模式间的相互耦合,提高OAM模式在光纤中的传输性能。其次在实验中演示这种MOF传输OAM模式,并利用特殊设计的光学旋涡达曼光栅对经过MOF传输后的OAM模式进行验证。(2)演示一种少模光纤(FMF)中CVB光束的传输与信号通信。首先使用有限元软件计算FMF所支持的本征矢量模式,分析FMF中各个本征矢量模式在不同波长下的有效折射率分布,对比它们之间的有效折射率差。其次在光学实验中演示CVB光束在FMF中的传输,测试不同CVB光束经过FMF传输后解调模式的纯度。并在后续通信实验中,利用两路同轴的高阶CVB光束,每路携带10Gbit/s的二进制启闭键控(OOK)信号,进行5km的光纤通信,测试通信系统的误码率,再结合同阶CVB光束的偏振复用,实现四路同轴CVB光纤通信,测试通信系统的误码率。系统的误码率满足带前向纠错功能(FEC)信道编码的最低阈值要求,符合光通信系统标准,实现了CVB光束的光纤传输、复用和通信。总之,本论文对OAM和CVB光束在光纤通信中进行基础与应用研究。将奇点光束的复用和解复用技术运用在光纤中,进行信息传输与通信,可以进一步提升光纤通信系统的容量,为今后数据中心中的光通信技术发展奠定基础。
[Abstract]:At present, the information society has entered the Internet era, and the rapid development of the Internet is increasing the demand for optical fiber communication bandwidth. On the one hand, the spectrum bandwidth of optical fiber communication is nearly saturated. On the other hand, with the continuous breakthrough of various multiplexing technologies, the capacity of optical fiber communication system increases dramatically, but the single-channel communication capacity of the existing single-mode optical fiber is close to the Shannon limit. Therefore, it is urgent to find new beam multiplexing technology and large capacity multiplexed fiber to meet the bandwidth requirement of optical fiber communication in the future. The singularity beam refers to the orbit angular momentum (OAM) beam based on the phase singularity and the polarization singular point cylindrical vector CVB beam. They provide a new degree of freedom for the beam multiplexing. However, the propagation of singularity beam in free space is easily affected by atmospheric disturbance and thermal turbulence, which leads to mode crosstalk due to the low purity of the propagating singularity beam. If the singularity beam carries the communication signal, the signal distortion may occur in the free space optical communication system, which will eventually lead to the signal being unable to demodulate at the demodulation end. The optical fiber provides the condition for the stable propagation of the singularity beam. In this paper, the multiplexing and demultiplexing technology of OAM and CVB beams is applied to optical fiber communication, and the basic and applied research on the propagation of OAM and CVB beams in optical fiber is carried out, which provides a new technical means and train of thought for the development of modern optical fiber communication. The main contents and results of this thesis are as follows: 1) demonstrating the propagation of OAM beams in a grapefruit microstructured optical fiber (MOF). Firstly, various intrinsic vector modes supported by grapefruit microstructured optical fibers are calculated by using finite element software, and the OAM modes formed by these optical fiber eigenvector modes are calculated by using the mode superposition theory. The effective refractive index difference between each intrinsic vector mode is over 10 ~ 2), which can effectively weaken the coupling between the modes and improve the transmission performance of the OAM mode in optical fiber. Secondly, the OAM mode of MOF transmission is demonstrated in the experiment, and the special designed optical vortex Darman grating is used to verify the OAM mode after MOF propagation. 2) to demonstrate the transmission and signal communication of the CVB beam in a small mode optical fiber (FMF). Firstly, the eigenvector modes supported by FMF are calculated by finite element software. The effective refractive index distributions of each eigenvector mode in FMF at different wavelengths are analyzed, and the difference of effective refractive index between them is compared. Secondly, the propagation of CVB beams in FMF is demonstrated in optical experiments, and the purity of demodulation modes of different CVB beams after FMF propagation is tested. In the subsequent communication experiment, using two high-order CVB beams of coaxial, each channel carries the 10Gbit/s binary on-off keying OOK signal, carries out the optical fiber communication of 5km, tests the error rate of the communication system, and combines the polarization multiplexing of the same order CVB beam. The four-channel coaxial CVB fiber communication is realized and the bit error rate of the communication system is tested. The error rate of the system meets the minimum threshold requirement of channel coding with forward error correction function and conforms to the standard of optical communication system. The optical fiber transmission multiplexing and communication of CVB beams are realized. In conclusion, the basic and application of OAM and CVB beams in optical fiber communication are studied in this thesis. The application of singularity beam multiplexing and demultiplexing technology in optical fiber for information transmission and communication can further enhance the capacity of optical fiber communication system and lay the foundation for the development of optical communication technology in data center in the future.
【学位授予单位】：深圳大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.11

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