面向光通信的光学涡旋传输特性及复用技术研究

发布时间：2018-04-05 10:14

本文选题：光学涡旋　切入点：光通信　出处：《深圳大学》2017年硕士论文

【摘要】：近年来,光学涡旋作为一种携带轨道角动量的特殊光束,因其独特的结构化螺旋相位波前以及暗中空的光强分布,使得其在光学操纵、光信息处理、光子计算机、量子通信、自由空间光通信领域具有重要的应用前景。特别是,基于涡旋光束的轨道角动量通信已成为近年来光通信领域的研究热点之一。在传统的光通信系统中,信息载波调制维度主要基于平面波,利用振幅、相位、频率、偏振态四个自由度作为信息的调制/复用,随之发展而来的技术包括调幅、调相、WDM、PDM等多种通信技术。而光学涡旋在平面波振幅、相位、频率以及偏振的基础上增加了一个新的维度——轨道角动量。并且,理论上来说,涡旋光束能够携带无穷正交的轨道角动量态,使用轨道角动量来进行信息的调制以及复用有望大幅提高光波的频谱利用率和通信容量。同时,由于OAM与其它物理量之间彼此独立,因此OAM通信技术能与现有的WDM、PDM等技术有机融合,实现OAM通信与传统光通信的无缝兼容。本文利用数值仿真的方法,探讨了双值涡旋光束在自由空间的传输特性,并通过改进达曼光栅实现了OAM信道的均衡,利用多值相息图来实现多路OAM光通信的复用及解复用。本文的主要工作内容如下所示:(1)分析了国内外通信技术领域的发展现状,指出光学涡旋在光通信研究领域巨大的研究价值,并简单探讨了光学涡旋可用于提高自由空间光通信系统通信容量的工作机理。(2)介绍探讨光学涡旋的基本理论和常见的产生方法,研究了光学涡旋在不同强度大气湍流影响下,相位和光强结构的变化趋势,及基于涡旋光束的OAM光通信如何有效的抵抗大气湍流的影响和提高通信系统性能的方法。(3)研究了双值LG高斯光束在自由空间中的传输特性,探讨了双值涡旋光束的相位和强度分布规律以及如何利用这种分布规律实现双值涡旋光束的产生和涡旋态检测,这为OAM光通信中实现快速判决涡旋态提供参考。(4)研究了达曼涡旋光栅在OAM光通信系统中的缺陷,并通过改进常见的达曼涡旋光栅结构实现光强的均匀分布,通过对OAM光通信中各OAM信道的的均衡,提高了误码性能。(5)设计了一种新型多值光学涡旋相息图,并将其应用于OAM自由空间光通信系统中,实现了四路OAM光束的复用/解复用,这种多值光学涡旋相息图有望于在未来的OAM光通信中得到广泛应用。
[Abstract]:In recent years, optical vortex, as a special beam with orbital angular momentum, has been used in optical manipulation, optical information processing, photonic computer, quantum communication, due to its unique structured helical phase front and dark space light intensity distribution.The field of free space optical communication has an important application prospect.In particular, orbital angular momentum communication based on vortex beam has become one of the research hotspots in the field of optical communication in recent years.In the traditional optical communication system, the dimension of information carrier modulation is mainly based on plane wave. The four degrees of freedom of amplitude, phase, frequency and polarization state are used as modulation / multiplexing of information.Phase modulation WDMN PDM and other communication technologies.The optical vortex adds a new dimension, orbital angular momentum, to the amplitude, phase, frequency and polarization of the plane wave.Moreover, in theory, vortex beams can carry an infinite orthogonal orbital angular momentum state. The use of orbital angular momentum to modulate and multiplexing information is expected to greatly improve the spectral efficiency and communication capacity of optical waves.At the same time, because the OAM and other physical quantities are independent of each other, the OAM communication technology can be integrated with the existing WDMPM-PDM technology to realize the seamless compatibility between OAM communication and traditional optical communication.In this paper, the propagation characteristics of two-valued vortex beams in free space are discussed by means of numerical simulation. The OAM channel equalization is realized by improving the Darman grating, and the multiplexing and demultiplexing of multichannel OAM optical communication is realized by using multi-valued phase information graph.The main work of this paper is as follows: (1) the present situation of communication technology at home and abroad is analyzed, and the great research value of optical vortex in the field of optical communication is pointed out.The working mechanism of optical vortex which can be used to improve the communication capacity of optical communication system in free space is briefly discussed. The basic theory and common generating methods of optical vortex are introduced. The influence of optical vortex on atmospheric turbulence with different intensity is studied.The variation trend of phase and intensity structure, and how the OAM optical communication based on vortex beam can effectively resist the influence of atmospheric turbulence and improve the performance of communication system.) the propagation characteristics of double-valued LG Gao Si beam in free space are studied.In this paper, the phase and intensity distribution of two-valued vortex beam is discussed, and how to use this distribution law to realize the generation of double-valued vortex beam and the detection of vortex state are discussed.This paper studies the defect of Darman vortex grating in OAM optical communication system, and realizes the uniform distribution of light intensity by improving the structure of Darman vortex grating.By equalizing each OAM channel in OAM optical communication, the error-code performance is improved. (5) A new multi-valued optical vortex phase graph is designed and applied to OAM free-space optical communication system to realize the multiplexing / demultiplexing of four-channel OAM beams.This multi-valued optical vortex phase map is expected to be widely used in the future OAM optical communication.
【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】：TN929.1

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