【作者】 王欣；

【导师】 张新亮；

【作者基本信息】 华中科技大学 ， 光学工程， 2007， 硕士

【摘要】 当前,40Gb/s密集波分复用(DWDM)光纤通信系统研究的不断深入。系统中的传输损伤:主要有噪声积累;色散,包括群速度色散(GVD)和偏振模色散(PMD);非线性效应,包括自相位调制(SPM)、交叉相位调制(XPM)、受激拉曼散射(SRS)、受激布里渊散射(SBS)和四波混频(FWM),成为限制通信容量进一步增加的瓶颈。新型调制格式是减轻这些损伤,提高频带利用率的40Gb/s系统的关键技术之一。本文针对适合40Gb/s系统的调制格式作了广泛而深入的研究,并获得一些创新性成果,主要有(1)在广泛阅读国内外相关文献的基础上,归纳总结了近年来新出现的主要调制格式的特点及产生方式。(2)创新性的提出了一种新的,用保偏光纤环镜(PMFLM)产生改进的双二进制归零(MD-RZ)码的方法。从理论上详细推导了产生过程;在40Gb/s环境下,用实验证明了该方法的可行性并得到良好的结果。(3)用Optisystem 3.1软件模拟了四种调制格式:非归零(NRZ)、归零(RZ)、光双二进制(ODB)、MD-RZ在40Gb/s系统中单信道和多信道的传输实验。分析比较了四种码型的在色散容限,非线性容限,传输距离上的优势及不足。MD-RZ在抗非线性效应及长距离传输中有独特的优势。(4)全面分析了“多功能光纤型全光码型转换器”的码型转换功能。归纳总结了四种主要的码型转换功能:NRZ到伪归零码(PRZ);RZ到NRZ;差分相移键控(DPSK)码到通断键控(OOK)码;DPSK到MD-RZ。更多还原

【Abstract】 At present, research on 40Gbit/s DWDM systems goes deeper. The bottleneck of further expanding system capacity is transmission impairments include accumulated noise from optical amplifiers, group-velocity dispersion (GVD), polarization mode dispersion (PMD) and fiber nonlinear effects such as self-phase modulation (SPM), cross-phase modulation (XPM), Stimulated Raman Scattering (SRS), Stimulated Brillouin Scattering (SBS) and four-wave mixing (FWM). Some modulation formats may to some extend overcome these transmission limitations and improve spectral efficiency. The paper deals with modulation formats and the main achievements are listed as the following(1) Domestic and foreign researches and development on advanced modulation formats are reviewed. Characteristics and generation methods of some primary modulation formats are presented.(2) A novel all-optical method is proposed out to generate Modified Duobinary RZ (MD-RZ) format by using a Polarization Maintaining Fiber Loop Mirror (PMFLM). Operation principle for all-optical format conversion is theoretically analyzed and 40Gb/s MD-RZ data format generation is experimentally demonstrated.(3) Transmission performance in 40Gb/s DWDM system of four modulation formats are simulated by Optisystem software. The four modulation formats are Non-Return to Zero (NRZ), Return to Zero (RZ), Optical Duobinary (ODB), and MD-RZ, performance of which are compared in terms of dispersion tolerance, non-linear tolerance, and transmission distance. MD-RZ has higher robust against non-linear effects and most suitable in ultra long transmission.(4) Comprehensive theoretical analysis and experiments on functions of "multi-functional fiber-based all-optical formats converter". Four major format conversions are concluded which are NRZ to Pseudo RZ (PRZ), RZ to NRZ, Differential Phase-Shift Keying (DPSK) to On-Off Keying (OOK), and DPSK to MD-RZ.更多还原