基于啁啾光纤光栅色散补偿问题的思考

色散已成为光纤长距离、高速率通信中的巨大障碍.鉴于色散补偿光纤插入损耗大、易引入非线性效应等缺点,文章采用啁啾光纤光栅对系统进行色散补偿,克服了以上不足.通过分析啁啾光纤光栅色散补偿的原理,结合理论分析,提出在多通道波分复用系统中使用啁啾光纤光栅,以实现长距离无中继传输.     

高斯脉冲在光纤中传输的光纤光栅色散补偿研究

高斯脉冲在光纤中传输一段距离后，啁啾系数和脉冲宽度均要发生变化，不同啁啾系数和脉冲宽度的高斯脉冲经过啁啾光纤光栅反射后的脉宽压缩特性也不同。本文介绍了啁啾高斯脉冲在光纤中的传输特性以及啁啾高斯脉冲经啁啾光纤光栅反射后的传输特性。理论分析和实验均表明，使用啁啾光纤光栅实现长距离色散补偿时，最佳色散补偿长度与光栅位置有关。     

光纤传输的色散补偿技术

如何解决光纤色散问题已引起全世界的关注，本介绍了激光预啁啾、中点光谱反转技术、光孤子通信、色散支持传输以及色散补偿光纤和啁啾光纤光栅色散补偿等多种解决方案的特点和局限性。     

高速传输系统的偏振模色散补偿技术

随着光网络的快速发展,系统的传输码率逐渐提升,传输技术也不断地发展和完善。光纤传输系统中的各种因素造成的影响程度也出现了很大的变化。针对偏振模色散(PMD)对高速光纤传输系统造成的损害,对目前光域和电域的PMD补偿技术进行详细的阐述。通过比较各种方案,指出高速光纤传输系统中PMD的光域补偿技术更适用,发展空间大,而且性能好。其中光纤光栅补偿技术应用广泛,对单信道和多信道传输系统都适用。因此,光纤光栅技术最具发展潜力。     

啁啾光纤光栅引起的系统色散功率代价

分析了啁啾光纤光栅对光脉冲信号的作用 ,计算光脉冲经过一定距离传输并由啁啾光纤光栅进行色散补偿后的脉冲展宽情况 ,同时分析啁啾光纤光栅群时延抖动对系统色散代价的影响。在系统色散功率代价一般要小于1dB的条件限制下给出啁啾光纤光栅群时延抖动的幅度、周期与系统单信道速率这三个参量之间存在相互关系     

色散补偿技术在1550nm模拟CATV长途传输系统中应用的研究

色散因素是制约1550nm模拟CATV系统无电中继传输距离的主要因素,本文提出利用已经商用化的色散补偿器件对长距离普通光纤CATV模拟传输系统中的色散进行补偿,并对比了色散补偿光纤和啁啾光纤光栅进行色散补偿的优缺点,同时文章给出了光纤光栅进行色散补偿的最佳位置。模拟系统采用皮长传输,采用啁啾光纤光栅实现对模拟信号的色散补偿可以充分发挥啁啾光纤光栅的低损耗的特性和对单波长进行补偿的特性,本文在国内首次提出采用啁啾光纤光栅（CFG）对1550nmCATV模拟系统长距离光纤传输进行了散补偿,并引用试验证明采用光纤光栅在保证较好载噪比（C／N）和三阶差拍失真（CTB）指标的情况下,能够大幅度地补偿二阶组合失真（CSO）的恶化。     

啁啾光纤光栅补偿光纤色散的研究

啁啾光纤光栅被认为是目前最有实用价值的色散补偿方案之一。分析了啁啾光纤光栅补偿色散的基本原理,从简单模型出发分析了啁啾光纤光栅的色散补偿能力,用数值法研究了啁啾光纤光栅的时延及色散特性,并比较了变迹型与非变迹型啁啾光纤光栅。结果表明要获得较大的色散,要求光纤光栅有较长的长度和较小的啁啾。同时为了消除色散曲线的振荡还必须采取适当的变迹方法。     

色散补偿技术在广东电网光传输网中的应用

根据光纤色散的产生机理,论述了解决色散限制的方法,结合色散补偿技术在广东电网省级光通信传输网中的实现应用,对色散补偿光纤和啁啾光纤光栅两种线性色散补偿技术的优缺点进行了比较.通过现网验证,建议在广东电网省级光通信传输网络中推广应用啁啾光纤光栅色散补偿技术.     

非啁啾光纤光栅在色散补偿中的应用

本文基于均匀布拉格光纤光栅的色散特性和啁啾高斯脉冲的传输演变特性,研究了工作于传输方式的非啁啾光纤光栅的色散补偿性能,讨论了光栅长度,光栅耦合系数等光栅参数以及初始脉宽,初始啁啾等脉冲参量对补偿光纤长度的影响。     

光脉冲在非啁啾光纤光栅中的透射传输研究

基于均匀布拉格光纤光栅的色散特性,阐述了激光啁啾脉冲的传输演变特性,研究了工作于传输方式的非啁啾光纤光栅的透射传输特性.讨论了光源线宽、光栅长度、光栅耦合系数等光栅参数以及初始脉宽、初始啁啾等参量对补偿光纤长度的影响,通过理论计算和模拟实验研究光栅对脉冲的补偿能力.     

Analysis of signal degree of polarization degradation induced by polarization-mode dispersion in optical fibers

We study analytically and numerically optical signal degree of polarization (DOP) degradation induced by polarization-mode dispersion (PMD) in optical fiber transmissions, using the Eyal-Marshall-Tur-Yariv (EMTY) model and Monte Carlo simulations. The results show the inaccuracy of second-order PMD approximation in the EMTY model and the inapplicability of employing DOP as feedback signal for high-order PMD compensation.     

高速光纤通信系统中一阶偏振模色散自动补偿技术的研究

偏振模色散(PMD)对10Gbit/s及更高速率的光纤通信系统的影响已不可忽略，因此PMD的补偿技术成为研究的热点问题。本文分析并通过实验验证了PMD引起的脉冲展宽对接收信号频谱的影响，在此基础上提出了一种PMD的补偿技术。在用保偏光纤模拟PMD效应的10Gbit/s的传输线路中实现了一阶PMD的自动补偿。     

偏振模色散仿真器特性研究

光纤通信线路的偏振模色散已成为高速、长距离光纤通信系统发展的主要障碍之一 ,其特性、测量以及补偿方法的研究成为目前光纤通信研究热点之一。偏振模色散仿真器 ,用于仿真传输链路的偏振模色散特性 ,不仅可用于偏振模色散补偿器 ,也可用于高速长距离光纤通信系统的规划设计等。本文分析了光纤偏振模色散仿真器的研究现状 ,归纳总结了现有偏振模色散仿真器的设计原理和结构特征 ,并用蒙特卡罗法对常用的偏振模色散仿真器的特性进行了数值模拟     

偏振模色散对高速光纤通信系统性能的影响

为研究偏振模色散对级联PSA高速光纤通信系统性能的影响,在了解PSA构成及放大原理后,利用耦合非线性薛定帶方程,采用计算机仿真技术研究不同信号脉冲波型与大小的光纤偏振模色散对级联PSA高速光纤通信系统性能的影响。仿真结果显示,高斯脉冲的眼图劣化度高于超高斯脉冲的眼图劣化度,PSA相位漂移逐渐增加时,眼图劣化度逐渐增加,PSA色散补偿功能更低,光纤通信系统性能更差,当脉冲指数是[2,2.5]时,级联PSA高速光纤通信系统性能最优;当偏振模色散值提升时,级联PSA高速光纤通信系统性能下降,但始终优于EDFA系统,优势性能并不显著,说明PSA具备偏振模色散补偿功能,却无法完全补偿偏振模色散。     

使用PSO算法的二阶偏振模色散自适应补偿实验

偏振模色散（PMD）已经成为高速光纤通信系统发展的严重障碍。我们将粒子群优化（Particle Swarm Optimization—PSO）算法作为偏振模色散自适应补偿中的反馈控制算法，对光链路中的PMD信号进行收索跟踪，并控制偏振控制器（Polarization Controller—PC），成功的实现了对二阶PMD的自适应补偿。实验结果表明，粒子群优化算法能够避免陷入局部极值而快速的搜索全局最佳值，同时它还具有很强的抗链路噪声的能力，补偿效果良好。     

PSO-based Control Algorithm for Polarization Mode Dispersion Self-adaptive Compensation

Polarization mode dispersion（PMD） is considered to be the ultimate limitation in high-speed optical fiber communication systems. Establishing an effective control algorithm for adaptive PMD compensation is a challenging task, because PMD possesses the time-varying and statistical properties. The particle swarm optimization（PSO） algorithm is introduced into self-adaptive PMD compensation as feedback control algorithm. The experiment results show that PSO-based control algorithm has some unique features of rapid convergence to the global optimum without being trapped in local sub-optima and good robustness to noise in the optical fiber transmission line that has never been achieved in PMD compensation before.     

Analysis of signal degree of polarization degradation used ascontrol signal for optical polarization mode dispersioncompensation

The basic property of degree of polarization (DOP) degradation of optical signal induced by polarization mode dispersion (PMD) in high-speed optical fiber transmission is investigated in detail. The DOP of the optical signal reflects the degree of waveform degradation caused by PMD, therefore, it is proposed to be used as the control signal judging the best compensation point for the optical adaptive PMD compensation techniques. However, the signal DOP is not only affected by PMD, but also by various factors, such as the modulation format, modulator chirp, fiber nonlinearity, amplified spontaneous emission (ASE), and so on. We use numerical simulations and experiments to explore the basic DOP property to detect PMD with these factors. We also show that using the signal DOP as control signal is especially useful for the optical duo-binary modulation because of its high sensitivity and wide PMD detection range     

Large PMD Compensated by Four Free Degrees in OTDM System

By introducing a two-stage polarization mode dispersion (PMD) compensator after a optical fiber link with a large PMD,over 270 ps first-order and 2 000 ps2 high-order PMD was compensated. The results show that the two-stage compensator can be used to PMD compensation in the 20 Gb/s optical time division multiplexing system with 60 km high PMD fiber. After compensating, the 270 ps DGD is changed into max. 7 ps. Moreover,the tunable FBG has a function of dispersion compensation.     

PSO2 based Control Algorithm for Polarization Mode Dispersion Self-adaptive Compensation

Polarization mode dispersion(PMD) is considered to be the ultimate limitation in high-speed optical fiber communication systems. Establishing an effective control algorithm for adaptive PMD compensation is a challenging task, because PMD possesses the time-varying and statistical properties. The particle swarm optimization(PSO) algorithm is introduced into self-adaptive PMD compensation as feedback control algorithm. The experiment results show that PSO2based control algorithm has some unique features of rapid convergence to the global optimum without being trapped in local sub-optima and good robustness to noise in the optical fiber transmission line that has never been achieved in PMD compensation before.     

Tracking and separation of time-varying principal states of polarization in optical fiber link for first-order PMD compensation and its filter-dependent performance

We propose a simple method for tracking and separating time-varying principal states of polarization (PSP) occurring in a fiber-optic transmission link with polarization mode dispersion (PMD) for use in PMD compensation. The proposed method uses as a feedback monitoring signal the bandpass-filtered RF power at bit-rate frequency for NRZ signal format. We demonstrated the operating principle of the method through theoretical simulation and experiment using an automatically adaptive PMD compensator employing a single polarization beam splitter (PBS). The effects of electrical filtering on the PSP tracking performance were also investigated by using three types of filters, i.e., a low-pass filter (LPF), a band-pass filter (BPF), and a high-pass filter (HPF). The simulation results showed that only a BPF centered at bit-rate frequency was found to allow for tracing and separation of two PSPs via PBS. The proposed method, when applied to a conventional PMD compensator that alternately controls a polarization controller and a delay line, enables separation of PSP control from differential-group-delay (DGD) control, thus allowing fast tracking of rapidly changing PSP in a PMD-impaired optical fiber link and reducing compensation time.