【作者】 曾祥烨；

【导师】 赵启大；

【作者基本信息】 南开大学 ， 光学， 2012， 博士

【摘要】 色散均衡技术是光纤通信系统的关键技术之一，而电域数字均衡技术与光域色散补偿技术相比，既有体积小、成本低的优势，又可以与数字信号处理技术相结合实现优异的性能，因此数字均衡技术成为光纤通信领域的研究热点之一。受益于超大规模数字集成电路工艺的发展，以及多进制调制、相干检测、偏振复用（PDM）等技术在光通信领域的应用，数字均衡技术已成为下一代100Gbit/s光网络的必备技术。相干检测不仅能提高接收机的灵敏度，而且能保持光纤色度色散和偏振模色散对信号影响的线性，适合作为长距离光纤通信系统的检测方案。偏振复用在不改变光纤链路的情况下，增加发射机和接收机的复杂度，使得系统传输容量翻倍。偏振复用相干检测与传统的多进制调制结合常称为单载波系统，而正交频分复用（OFDM）则是多载波调制，它增加了系统的灵活性，并提供了100Gbit/s以上系统传输容量的能力。本论文主要研究偏振复用相干检测单载波系统和光正交频分复用系统的数字色散均衡技术。本论文的工作是在河北省自然科学基金项目（No. F2008000116）和国家自然科学基金项目（No.60572018）的支持下进行的。主要研究内容有：1.根据非线性薛定谔（NLS）方程，分析了30ps以上光脉冲在长距离光纤中的传输方程，研究了群速度色散（GVD）和偏振模色散（PMD）对光信号传输的影响，并分析了偏振模色散的补偿原理；研究了偏振复用相干检测单载波系统和光正交频分复用系统的线性信道模型，分析了光纤信道色度色散（CD）和偏振模色散的矩阵模型，建立了112Gbit/s偏振复用相干检测单载波系统和光正交频分复用系统的仿真模型。2.针对100Gbit/s偏振复用相干检测单载波系统，提出了一种以蝶形复数有限冲激响应（FIR）滤波器为基本结构的数字色散均衡器，以递归最小二乘（RLS）算法实现自适应，并与最小均方（LMS）算法实现自适应的均衡器相比较。仿真分析了两种算法更新的均衡器在不同信道线性损伤条件下的均衡性能。实验结果表明：递归最小二乘算法对信道残留色度色散和偏振模色散的均衡效果优于最小均方算法，在25抽头均衡器的配置下，它能以2.74dB的光信噪比代价同时补偿1760ps/nm的残留色度色散和104.9ps偏振模色散引起的平均差分群时延，与同等条件下的最小均方算法相比有2.23dB的性能提升。3.提出了一种用于100Gbit/s偏振复用相干检测单载波系统的数字色散均衡器，以蝶形复数无限冲激响应（IIR）滤波器为基本结构，以最小均方算法完成自适应。仿真分析了该均衡器在不同信道线性损伤条件下的均衡性能。实验结果表明：在21前馈抽头+2反馈抽头的配置下，该均衡器能以2.95dB的功率代价同时补偿1440ps/nm的残留色度色散和95ps的平均差分群时延。4.提出了一种基于凯撒窗函数的改进的符号内频域平均（ISFA）算法，用于改善100Gbit/s偏振复用相干检测光正交频分复用系统的信道估计和均衡在噪声环境下的性能。仿真分析了不同系统条件下改进算法与原算法的信道估计均衡性能。实验结果表明：基于凯撒窗的改进的符号内频域平均算法比原算法在性能上有所提升。改进算法用于补偿1000km常规单模光纤的群速度色散和偏振模色散达到前向纠错码（FEC）要求的误码率上限所需的光信噪比为15.73dB，比原算法低0.24dB。改进算法用于补偿900km常规单模光纤的群速度色散和偏振模色散所需的光信噪比代价为3.01dB，比原算法低0.35dB。更多还原

【Abstract】 Dispersion equalization is one of the key technologies for modern fiber opticcommunication systems. Compared with the optical dispersion compensation, theelectronic digital equalization has smaller size and lower cost, and it can achieveexcellent performance with the combination of digital signal processing. Digitalequalization techniques become one of the hot research fields of optical fibercommunication. Benefit from the development of ultra-large-scale digital integratedcircuit technology, as well as the M-ary modulation, coherent detection andpolarization division multiplexing (PDM) technology in the field of opticalcommunications, digital equalization has become an essential technology of the nextgeneration100Gbit/s optical networks.Coherent detection can not only improve the receiver sensitivity, but alsomaintain the linearity of chromatic dispersion and polarization mode dispersioneffects, and is suitable for the detection scheme of long-haul fiber opticcommunication systems. Polarization division multiplexing does not change the fiberlink, making the system transmission capacity doubled via increasing the complexityof the transmitter and receiver. The combination of polarization division multiplexing,coherent detection and M-ary modulation often referred to as single-carrier systems.Orthogonal frequency division multiplexing (OFDM) is a multi-carrier modulationscheme. It increases the flexibility of the system, and provides the ability of a100Gbit/s and above system transmission capacity. This research mainly investigates thedigital dispersion equalization technologies for polarization multiplexed coherentsingle-carrier system and optical orthogonal frequency division multiplexing system.The work in this thesis is supported by the Hebei Province Natural ScienceFoundation (No. F2008000116) and the National Natural Science Foundation (No.60572018). The main contents are as follows:1. After analyzing the nonlinear Schrodinger equation of optical pulses above 30ps in the long-haul optical fiber, the effect of group velocity dispersion(GVD) and polarization mode dispersion (PMD) on optical signaltransmission is studied, and the compensation principle of polarization modedispersion is analyzed. The linear channel model of the polarizationmultiplexed coherent single-carrier system and optical orthogonal frequencydivision multiplexing system is studied, and a matrix channel model of fiberchromatic dispersion (CD) and polarization mode dispersion is analyzed.Simulation model for112Gbit/s polarization multiplexed coherentsingle-carrier system and optical orthogonal frequency division multiplexingsystem are created.2. A butterfly finite impulse response (FIR) filter based structure is proposedfor the digital dispersion equalizer of100Gbit/s polarization multiplexedcoherent single-carrier system, which adopt least mean square (LMS)algorithm and recursive least squares (RLS) algorithm as the adaptivealgorithm. Simulation analyses of the equalization performance of twoalgorithms updated equalizer under different channel impairments arecarried out. The simulation results show that: the equalization performanceof the recursive least squares algorithm better than the least mean squarealgorithm, with the configuration of the25-tap equalizer, recursive leastsquares algorithm can compensate1760ps/nm residual chromatic dispersionand104.9ps mean differential group delay (DGD) caused by polarizationmode dispersion simultaneously with2.74dB optical signal to noise ratio(OSNR) penalty, and has2.23dB performance improvement compared withthe least mean square algorithm under the same conditions.3. A butterfly infinite impulse response (IIR) filter based structure is proposedfor the digital dispersion equalizer of100Gbit/s polarization multiplexedcoherent single-carrier system, which adopts least mean square algorithm asthe adaptive algorithm. The equalization performances of the designedequalizer are analyzed by simulation under different channel linearimpairments. The simulation results show that: with the configuration of21feed forward taps and2feed back taps, the equalizer can compensate 1440ps/nm residual chromatic dispersion and95ps mean differential groupdelay simultaneously with2.95dB power penalty.4. An improved intra-symbol frequency domain average algorithm using theKaiser window function is proposed to improve the channel estimation andequalization performance of100Gbit/s polarization multiplexed coherentoptical orthogonal frequency division multiplexing system in noisyenvironments. The channel estimation and equalization performances of theimproved algorithm and original algorithm are analyzed through simulationunder different system conditions. The simulation results show that: theKaiser-window-based improved algorithm has improved performance thanthe original algorithm. To compensate the group velocity dispersion andpolarization mode dispersion of1000km transmission fiber and achieve thebit error rate upper limit required by forward error correction (FEC) code,the improved algorithm need an OSNR of15.73dB,0.24dB lower than theoriginal algorithm. To compensate the group velocity dispersion andpolarization mode dispersion of900km transmission fiber, the optical signalto noise ratio penalty of the improved algorithm is3.01dB,0.35dB lowerthan the original algorithm.更多还原