【作者】 李俊；

【导师】 胡必春；

【作者基本信息】 华中科技大学 ， 光电信息工程， 2013， 硕士

【摘要】 在高速发展的宽带数据传输业务需求的推动下光纤通信系统正朝着“超高速率、超大容量、超长距离”（3U）方向发展。虽然传统EDFA和WDM技术极大地延长了传输距离和容量，但同时也带来了新的问题。噪声，色散（CD）和非线性损伤的积累已经成为限制系统性能的主要因素。相干光通信系统具有接收机灵敏度高、波长选择性好、适用各种调制格式、光谱效率高等优点，结合数字信号处理（DSP）技术还可以对各种信号损伤进行补偿，能够极大的提高3U光传输系统的性能，被认为是3U光传输系统发展的必然趋势。目前光纤传输中的线性损伤如CD，PMD都已经有了比较有效的补偿方法，但是非线性效应由于具有动态适变的特性，其补偿技术一直是一个难点。数字相干光通信系统中信号光场可以通过相干检测而被线性的接收，这为基于DSP的非线性补偿技术的发展提供了新的契机。本论文围绕基于DSP的相干光通信系统中的非线性补偿技术展开深入研究。首先系统分析和总结了目前DSP补偿技术的研究与发展现状；其次通过所建立的理论模型研究和分析了非线性损伤的机理和对高级调制格式光传输系统性能的影响；然后围绕基于数字反向传输（DBP）算法的带内非线性损伤补偿方法展开了深入的研究，针对不同采样速率和剩余色散条件下DBP算法的效果进行了比较，对DBP算法中关键参数的影响进行了分析和优化，经过优化后系统的Q值可以提高0.5~2.1dB；进而为解决DBP算法计算复杂度高实时处理困难的问题，针对色散管理和非色散管理系统，开发和研究了折叠DBP算法和低通滤波DBP算法，有效减少参数偏离最佳值时补偿效果的劣化，并能够在保证补偿效果的同时减少计算量达1个数量级以上。最后基于VPI TransmissionMaker和Matlab仿真平台验证了上述改进DBP方案在PDM-QPSK和PDM-16QAM光传输系统中的有效性。更多还原

【Abstract】 To satisfy the ever-increasing demand of broadband data transmission service, theoptical fiber communication systems are developed toward “ultra-high speed, ultra-largecapacity and ultra-long haul (3U)” transmission systems. Although the transmission distanceand capacity have been greatly improved after Erbium Doped Fiber Amplifier (EDFA) andWavelength Division Multiplex (WDM) technologies were invented, new challenges likeaccumulation of ASE noises, chromatic dispersion (CD) and nonlinear distortions havebecome the bottle neck of the next-generation fiber optic communication system. Coherentoptical transmission system has several merits such as high sensitivity, accurate wavelengthselectivity, compatibility with different advanced modulation formats and high spectralefficiency et al. Moreover, in combination with DSP technology, the various distortions canbe compensated effectively in such systems. Thus digital coherent detection has beenconsidered as the key technique for3U systems.Now the linear distortions like CD and Polarization Mode Dispersion (PMD) can beeffectively compensated with DSP algorithms, but due to the complexity of nonlinear effects,the nonlinear distortions compensation becomes the main constraints of3U systems. In thisthesis, digital signal processing (DSP) algorithms are intensively investigated to compensatefor nonlinear distortions impairments in coherent optical transmission systems. First, thedevelopment of the DSP based compensation technologies are comprehensively analyzedand summarized. Second, the mechanism and impact of the nonlinear effects in optical fibersare studied based the theoretical model. Their influences on3U transmission systems withadvanced modulation formats are also analyzed. Thirdly, the digital backward propagation(DBP) algorithm is investigated to compensate the intra-channel nonlinear distortions due toself phase modulation (SPM). The performance of DBP is systematically analyzed underdifferent sampling rates and residual CD values. The key parameters are optimized toimprove the performance, the system Q factor can be improved about0.5~2.1dB after theoptimization. Forth, to reduce the computational complexity, improved DBP algorithm, i.e.folded DBP and low pass filtered DBP, are developed for dispersion managed andun-managed systems. The impact of the deviation of the parameters from optical value isreduced. With equivalent performance the computational complexity can be reduced by a factor of ten. Finally the effectiveness of the DBP algorithms is verified using VPITransmissionMaker and Matlab for3U transmission systems with polarization multiplexedQPSK and16QAM formats.更多还原