光载正交频分复用（O-OFDM）技术是一种新型的光纤通信技术，基本思想是将正交频分复用（OFDM）技术应用于光纤通信中，构造出高速率、大容量、低成本的光正交频分复用（O-OFDM）传输系统，该系统具有光纤通信系统和OFDM技术的双重优点。与传统的光通信技术相比，O-OFDM具有更高的频谱利用率、更强的抗色散和非线性效应的能力。在现有的光网络基础上很容易实现升级和扩容，近年来受到研究者得广泛关注。 简述了光纤通信系统发展近况以及OFDM技术的基本原理和目前OFDM技术的应用领域，分析了OFDM系统较传统的单载波系统以及频分复用技术（FDM）所具备的优势，论述了O-OFDM系统的两种基本形式：直接检测光OFDM（DDO-OFDM）系统和相干检测光OFDM（CO-OFDM）系统；文章采用光通信仿真软件OptiSystem和MATLAB软件，搭建了O-OFDM系统的仿真平台，在此基础上对O-OFDM系统的关键技术做了深入的研究和分析。 一、从理论上分析了DDO-OFDM信号的两种映射方式；分别讨论了DDO-OFDM系统的线性映射和非线性映射；通过仿真结果分析了DDO-OFDM系统的传输性能和误码性能，即系统的误码率、耦合光功率、传输距离和信噪比之间的关系。 二、论述了CO-OFDM系统的工作原理及各个模块功能，并建立了CO-OFDM系统仿真平台，对与DDO-OFDM系统最大不同的光电检测模块和电光调制模块进行了特别的分析，通过仿真结果分析了不同调制方式和不同参数下CO-OFDM系统的传输性能和误码性能。 三、研究了O-OFDM系统的关键技术，提出了一种时域相移补偿方法，相位补偿主要用来矫正因色散导致的非随机性相位噪声，通过均衡进一步消除了系统的非线性效应、光器件的相位噪声不理想因素造成的相位噪声。仿真结果验证了此相位补偿方法的可行性和有效性。 四、分析了系统的同步问题，研究由于符号定时同步偏差对系统性能的影响，对O-OFDM系统Schmidl&Cox算法进行了理论分析和仿真实现，分析了为克服Schmidl&Cox算法中符号定时同步的不确定性而采用涉及新的训练符号的Minn算法，且通过仿真在系统中得以实现，进一步的改善了系统的性能。 五、分析了OFDM符号的峰均比(PAPR)，O-OFDM仿真系统中高的PAPR出现的概率不是很大，因此本文采用限幅类方法对PAPR加以抑制，通过仿真验证，系统输出结果图表明，限幅法有效地降低了O-OFDM系统PAPR，进一步解决了接收端因PAPR引起的QAM星座图紊乱问题，改善了信号的质量，延长了传输的距离。 总体上看，O-OFDM相对于传统的复用技术来说，降低了色散管理的复杂度，提高了系统的频谱效率；理论分析和仿真结果表明，O-OFDM系统在超长距离、更高速率的光纤传输系统中有着很好的应用前景。

ABSTRACT Optical orthogonal frequency division multiplexing (O-OFDM) is a new communication technology.The basic idea is to apply OFDM technology into optical fiber communication. We show that optical OFDM combines the merits of coherent and OFDM technologu.Thus,it can constructed high-speed, large capacity and low cost optical OFDM transmission system. Compared with the traditional optical communication technology, the system has the stronger ability to resist dispersion and nonlinear effect of optical fiber. Besides,it is easier to upgrade and make expansion.So people pay attention to it in last for years. First of all, the article has introduction of recent development of optical fiber comunincation,and the basic principle and OFDM application field are stated. Next, the two basic forms of O-OFDM are described: direct detection optical OFDM (DDO-OFDM) system and coherent optical OFDM (CO-OFDM) system. The system combines MATLAB software with OptiSystem to construct simulation platforms for the two systems, and we analysis of the performance of the two systems deeply on the basis platforms. Firstly,theoretical analysis on mapping mode of DDO-OFDM system is presented. The mapping methods of DDO-OFDM ,which are linear mapping and nonlinear mapping are discussed respectively.Then, transmission performance and BER performance of DDO-OFDM system are discussed by simulation platform.In other words,we research on connection of bit error rate (BER), coupled optical power,transmission distance and optical Signal to noise ratio. Secondly, it elaborates operating principle of CO-OFDM and the performance of each module,and simulates the transmission performance and BER performance of CO-OFDM on different modulation. Thirdly,the key technologies of O-OFDM system are researched,and the method to compensate phase offset is proposed. Compensation of phase shift is used to correct randomness phase noise due to dispersion effect. The randomness noise which is related with signal frequency and the other random noise are discussed respectively.The simulation result confirms that the compensation method has good feasibility and effectiveness. Forthly,Synchronization problem is studied.It is only to deliberate the affect caused by timing synchronization offset,on optical OFDM system,because it is a simulation system not a real system.Detailed discussion of the synchronizations are simulated on O-OFDM,which are Schmidl&Cox and Minn algorithm.The result shows that the performance is improved. Finaly,the optical OFDM system adopts amplitude-limited to reduce PAPR of optical OFDM system.From output constellation figure,it can conclude that the method improves the signal quality,solves the disorder of QAM constellation and extend the transmission distance. In a word,compared with the traditional optical communication technology, O-OFDM reduced the complexity of dispersion management and improved spectrum efficiency. The theoretical analysis and simulation results can show that O-OFDM system has obvious advantages and research value. Particularly,O-OFDM has the very good application prospects for ultra long haul and the high speed optical fiber communications.