基于双波长激光器产生毫米波技术研究及其性能分析

发布时间：2019-03-11 14:11

【摘要】：随着通信技术的发展,用户对通信业务移动化和宽带化的需求日益增强。光载无线通信(ROF)作为一门新兴的宽带接入技术,满足了通信系统大容量和移动化的要求。毫米波作为ROF系统的发射源和本振源,其性能和生成方法对ROF系统至关重要。目前主要使用光学方法生成毫米波,相比具有大相位噪声的电子学方法,光子学方法有很大的优势,但同时也有不足。本文针对毫米波光学生成技术展开研究,在二次外差法的基础上,提出了一种基于双波长激光器产生毫米波的方案,并对影响该方案的因素做了理论和仿真分析,其中包括系统相位噪声、激光器线宽及光纤色散等因素。本文的研究工作主要体现在以下几个方面:(1)首先介绍了研究课题的背景意义。重点介绍了 ROF技术,包括ROF系统原理、结构分类及系统技术优势,并分析了 ROF技术的应用现状。(2)介绍了毫米波及毫米波通信,包括毫米波传播方式及毫米波通信的优势。分析了目前已有的光生毫米波的原理和系统结构,包括直接强度调制、外部调制技术、上变频技术和光外差技术等,并分析了各种技术的优势和不足。(3)在二次外差法的基础上,提出了一种基于双波长激光器产生毫米波的方案。详细介绍了方案中应用到的光学器件的结构原理和数学模型,包括马赫曾德尔调制器(双平行马赫曾德尔调制器)、光电检测器和光纤布拉格光栅。给出了该方案的系统原理图,并对该方案进行了理论分析,得到了八倍频于本振信号的毫米波,并通过光学仿真软件OptiSystem对该系统进行仿真,得到了 60GHz的毫米波,通过仿真分析验证了该方案的可行性。(4)对影响本方案系统性能的因素进行了探讨,包括系统相位噪声、光纤色散及激光器线宽。通过理论分析,得到了产生毫米波功率代价与光纤长度、毫米波功率代价与激光器线宽关系的数学模型。并通过Matlab仿真,得出了毫米波功率代价随着光纤色散的增大、激光器线宽的增加而增大的结论。并通过OptiSystem仿真,得到了不同激光器线宽条件下系统的眼图及误码率,进一步说明了激光器线宽对系统性能的影响。通过理论分析建立数学模型,得出理想状态下该方案生成的毫米波信号不受相位噪声的影响的结论,并通过OptiSystem10.0中仿真分析,在60GHz频率处解调出原始基带信号,证实了产生的60GHz毫米波的性能未受到相位噪声的影响。(5)总结分析了本文中基于双波长激光器及基于二次外差法产生毫米波方案的优势和不足,并给出了今后工作研究的建议。
[Abstract]:With the development of communication technology, the demand for mobile and broadband communication services is increasing day by day. As a new broadband access technology, optical-borne wireless communication (ROF) meets the requirements of large capacity and mobility of communication systems. Millimeter wave is the source and local source of ROF system. Its performance and generation method are very important to ROF system. At present, optical method is mainly used to generate millimeter wave. Compared with the electronic method with large phase noise, photonics method has great advantages, but it also has some disadvantages at the same time. Based on the secondary heterodyne method, a scheme of millimeter wave generation based on dual-wavelength laser is proposed in this paper, and the factors affecting the scheme are analyzed theoretically and simulated. These factors include system phase noise, laser linewidth and fiber dispersion. The research work of this paper is mainly reflected in the following aspects: (1) first, the background significance of the research topic is introduced. This paper focuses on the introduction of ROF technology, including ROF system principle, structure classification and system technical advantages, and analyzes the application status of ROF technology. (2) the millimeter wave and millimeter wave communication, including millimeter wave propagation mode and advantages of millimeter wave communication, are introduced. The principle and system structure of light-generated millimeter wave are analyzed, including direct intensity modulation, external modulation, up-conversion and optical heterodyne, etc. The advantages and disadvantages of various techniques are analyzed. (3) based on the quadratic heterodyne method, a scheme of millimeter wave generation based on dual-wavelength laser is proposed. The structure principle and mathematical model of the optical devices used in the scheme are introduced in detail, including Mach-Zehnder modulator (double parallel Mach-Zehnder modulator), photodetector and fiber Bragg grating (FBG). The schematic diagram of the scheme is given, and the theoretical analysis of the scheme is carried out. The millimeter wave with eight times the frequency of the local vibration signal is obtained. The system is simulated by the optical simulation software OptiSystem, and the millimeter wave of the 60GHz is obtained. The feasibility of the scheme is verified by simulation analysis. (4) the factors affecting the system performance, including phase noise, fiber dispersion and laser linewidth, are discussed. Based on the theoretical analysis, the mathematical models of the relation between the power cost of millimeter wave and the length of fiber, the power cost of millimeter wave and the linewidth of laser are obtained. Through Matlab simulation, it is concluded that the millimeter wave power cost increases with the increase of fiber dispersion and laser linewidth. The eye diagram and bit error rate (BER) of the system under different laser linewidth conditions are obtained by OptiSystem simulation, and the influence of laser linewidth on system performance is further explained. Through theoretical analysis and establishment of mathematical model, it is concluded that the millimeter wave signal generated by this scheme is not affected by phase noise in ideal state, and the original baseband signal is solved at 60GHz frequency by simulation analysis in OptiSystem10.0. It is proved that the performance of the generated 60GHz millimeter wave is not affected by the phase noise. (5) the advantages and disadvantages of the two wavelength laser based millimeter wave generation scheme and the quadratic heterodyne method in this paper are summarized and analyzed. At the same time, some suggestions for future research are given.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN248;TN929.1

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