Adaptive PMD compensation experiment in 40 Gb/s CSRZ system

In 40 Gb/s systems with low polarization-mode dispersion(PMD) fibers,first-order PMD is the dominate factor with quite small value. An adaptive PMD compensator consisting of an electrical polarization controller(PC) ,a section of polariza-tion maintaining fiber(PMF) ,a degree of polarization(DOP) detector and a feedback control module is employed in 40 Gb/s NSFCNet. This compensator has a simple structure and high speed,which can compensate up to 20 ps first-order PMD adaptively and the average searching time is 2 ms.     

用于40 Gb/s系统的可编程光纤挤压式PMD模拟器

用于40Gb/s系统的可编程全光纤偏振模色散(PMD)模拟器,采用一个电控光纤挤压式偏振控制器(PC)连接两段高双折射光纤的方案,该方案结构简单,PMD变化周期为1ms,输出偏振态在邦加球上均匀分布。能产生0～22ps的群时延差(DGD)以及0～121ps^2的二阶PMD。通过程序控制,可以产生各种均值的Maxwell分布。脉冲展宽实验和10 Gb/s系统眼图实验证明该模拟器性能良好。     

对40 Gb/s OTDM系统中光纤光栅色散补偿器进行偏振模色散补偿的研究

改变光纤光栅紫外曝光系统 ,在相位掩模板后插入一个旋转装置 ,使得光纤在制作过程中可以进行某种旋转。通过这种方法制作的光纤光栅偏振模色散减小到平均差分群时延 (DGD)约为 0 2ps,而没加旋转制作的光纤光栅平均DGD约为 18 2 ps。采用两个这种低偏振模色散 (PMD)的光纤布拉格光栅 (FBG) ,成功地在 4 0Gb/s光时分复用 (OTDM)系统中补偿了约 2 0 4 0 ps的色散 ,该系统在经过 12 2km普通单模光纤传输后 ,未发现PMD的影响 ,传输功率代价小于 1 4dB。     

40 Gb/s CSRZ码系统下的自适应PMD补偿实验

在采用了新型光纤的40Gb／s系统中，通常只有很小的一阶偏振模色散（PMD）。本文在40Gb/s的国家自然科学基金网（NSFCNET）上，搭建了由电控偏振控制器（PC）、保偏光纤（PMF）、信号光偏振度（DOP）检测单元以及反馈控制单元组成的PMD补偿模块，具有结构简单、反应灵敏的特点，可以对小于20ps的一阶PMD进行自适应的补偿，平均搜索时间为2ms。     

Dynamic PMD Mitigation at 10 Gb/s Using Viterbi Equalization in DPSK Systems

Compensating dynamically changing polarization- mode dispersion (PMD) is important for optical fiber transmission systems. We present simulations of a Viterbi equalization for dynamic PMD mitigation in 10-Gb/s nonreturn-to-zero differential phase-shift keying systems. The equalizer can dynamically track fast varying differential group delay (DGD) and achieve similar performance to static DGD.      

40 Gb/s光纤通信系统中一阶PMD对信号频谱的影响

首先给出了受一阶偏振模色散(PMD)影响的40 Gbit/s高斯脉冲信号功率谱的数学表达式,并分析了脉冲波形、分光比、监测频率以及差分群延时(DGD)对接收信号功率谱的影响.实验测量了在分光比为0.5时的40 Gbit/s归零(RZ)码伪随机信号在接收频率为12 GHz处的电功率谱密度随DGD变化的关系,实验结果与理论计算一致.这表明,对于40 Gb/s的光纤通信系统,可以通过简单地检测某一特定频率的电信号功率,动态跟踪系统中PMD的变化情况,从而为补偿一阶PMD提供了重要依据.     

DM solitons in long-haul DWDM systems at 40 Gb/s with nonlinear interactions and PMD

The authors investigate for the first time how polarization mode dispersion and nonlinear interactions affect dense wavelength division multiplexing dispersion management-soliton long-haul transmission using Monte Carlo simulations. They also discuss how the system is affected by an increasing number of wavelength channels.     

应用于40Gb/s光传输系统新兴调制方式

阐述了双偏振正交相移键控(DP-QPSK)系统的调制编码和检测原理,详细描述关于DP-QPSK40Gb/s WDM系统结构和性能的最新研究进展,并将DP-QPSK与Duo-Binary、DPSK和DQPSK等几种调制编码方式进行了全面比较,展示了DP-QPSK作为一种新兴的调制方式,在400b/s系统研究领域具有很高的研究价值和广泛的应用前景.     

Electro-optic polymer-based modulator design and performance for 40 Gb/s system applications

We investigate the potential performance of polymer-based electro-optic (EO) modulators for high-speed systems at 40 Gb/s and beyond. General strategies and specific designs are presented to reduce the modulator half-wave drive voltage while maintaining a broadband response. In addition, we consider practical system requirements that may allow the relaxation of certain modulator design parameters to further improve performance. Designs are presented that may enable a 3-dB electrical bandwidth of 30 GHz with a single-ended half-wave drive voltage of /spl sim/1.6 V for 1.3-/spl mu/m light assuming an effective EO coefficient of 30 pm/V in the waveguide core.     

基于10 Gb/s传输链路的40 Gb/s光传输实验研究

基于中国自然科学基金网(NSFCNet)的400 km×10 Gb/s光传输链路实现了40 Gb/s光传输,没有出现误码率(BER)平台,说明在常规的中短距离10 Gb/s系统可以直接升级至40 Gb/s系统,而不需要升级传输链路。但是,由于相对10 Gb/s系统而言40 Gb/s系统的色散容限非常小,在升级时必须精确补偿原有链路的色散,在接收机前一般需要加可调色散补偿单元。同时,还分析了光纤注入功率对系统性能的影响,结果表明在设计这种由10 Gb/s向40 Gb/s升级的系统时,不仅要考虑信号带宽增加带来信噪比要求的提高,而且必须充分考虑光纤非线性的影响。     

40Gb/s DWDM系统不同码型传输性能的比较

采用Optisystem软件,对比分析了非归零码(NRZ)、归零码(RZ)、载波抑制归零码(CS-RZ)和载波抑制归零差分相移键控码(CSRZ-DPSK)四种码型在8×40Gb/s DWDM系统的传输性能。结果表明,CSRZ-DPSK码抗色度色散和PMD性能最优,CS-RZ码的OSNR容限最低。当入纤光功率适中、色散和色散斜率同时补偿时,CSRZ-DPSK码和CS-RZ码的最大传输距离超过2700km。     

10Gb/s光网络向40/100G b/s演进的扩容方法

随着需求的增长,业务提供商一直都面临着光网络带宽扩容的压力.在新的技术条件下,以往靠增加网络规模来进行扩容的常规方法已经受到越来越多的局限.文章从常规带宽扩容手段的局限性入手,介绍和分析了DP-QPSK等当前热门的带宽扩容技术在光通信网络由10Gb/s向40/100Gb/s演进过程中的广阔前景及存在的不足.     

40Gb／s波分系统设备技术

随着40Gb／s端口路由器的出现,未来几年内40Gb／s波分系统设备将取代现有的10Gb／s波分系统设备,就像前几年10Gb／s波分系统设备取代2．5Gb／s波分系统设备一样。然而,40Gb／s波分系统有很多传输限制因素,包括光放大器自发辐射噪声、光纤非线性效应、色散、偏振模色散等等。为实现40Gb／s的波分传输,采取新型调制码型、可调色散补偿、偏振模色散补偿等措施至关重要。     

基于DOP反馈的10 Gb/s系统PMD自适应补偿实验

报道了基于DOP反馈的10 Gb/s NRZ码和RZ码光通信系统的PMD自适应补偿实验,自适应补偿器的搜索时间低于1 s,受到突然扰动后的恢复时间少于20 ms.     

Dynamic post dispersion optimization at 40 Gb/s using a tunablefiber Bragg grating

A compact tunable fiber Bragg grating that uses distributed thin-film heaters on the surface of the fiber is used to dynamically optimize the post dispersion compensation of a multi-span 40-Gb/s nonreturn-to-zero (NRZ) transmission system. Dynamic post dispersion compensation with this device enables the system to operate over a much wider range of launch power than is otherwise possible with simple, fixed compensation using dispersion compensating fiber     

Bandwidth virtualization enables long-haul WDM transport of 40 Gb/s and 100 Gb/s services

This article describes how bandwidth virtualization can enable transmission of ultra-high bandwidth 40 Gb/s and 100 Gb/s services over existing optical transport networks independently of the underlying network infrastructure. An overview of the technology alternatives available to enable high-bandwidth service transport is provided, along with a discussion of the relative merits of different approaches. The authors describe how wavelength division multiplexing, using large- scale photonic integrated circuits combined with the use of a digital virtual concatenation mapping protocol, can be used to enable decoupling of 40 Gb/s and 100 Gb/s service provisioning from the underlying optical link engineering, thereby enabling bandwidth virtualization. Real-world implementation examples of bandwidth virtualization are provided, including 40 Gb/s service transmission over a 2000-km fiber link with 65 ps of peak PMD, a field trial of 40 Gb/s service transmission over an 8477-km trans-oceanic network, and finally a field trial of a pre-standard 100 gigabit Ethernet service transmission over a 4000-km terrestrial long-haul network.     

40Gb/s光通信系统不同码型传输性能分析

使用Optisystem仿真工具,对非归零(NRZ)、归零(RZ)、载波抑制归零(CS-RZ)和归零差分移相键控(RZ-DPSK)四种码型在40Gb/s单信道传输系统中的灵敏度、非线性效应和色散容忍度进行比较,并对标准单模光纤(G.652)中四种码型的单信道40Gb/s长距离传输进行了仿真,结果表明:CS-RZ具有更优的灵敏度和抗噪声能力,RZ-DPSK码具有更优的非线性容忍度.在较低入纤功率条件下,G.652光纤作为传输介质,CS-RZ系统的传输性能最优.     

Implementation of area optimization precoder in a 40 Gb/s PolDM-DQPSK system

In this paper, a new model based on an improved Brent Kung (BK) parallel prefix network (PPN) algorithm is proposed and realized in the field programmable gate array (FPGA). This model is employed in the implementation of 20 Gb/s differential quadrature phase-shift keying (DQPSK) precoder in 40 Gb/s polarization division multiplex (PolDM) DQPSK system. In the computation process, the computation complexity (area) optimization with fan-out limited is achieved. In the implementation, 770 FPGA slice registers are utilized, which save about 60% logic resources compared with the previous Kogge Stone (KS) algorithm.     

40Gb/S甚短距离光传输系统的去斜移设计(本期优秀论文)

实现了串/并转换成帧器接口(SFI-5)的去斜移功能.该设计主要由去斜移通道的帧对齐模块和数据通道去斜移模块组成,其中的关键电路由窗口比较器与滑动窗口生成器配合工作实现.16个数据通道去斜移电路轮流工作,共用一个窗口比较器,提高了电路的工作速度,节省了资源.系统测试表明,该电路可纠正±160比特范围内的通道间斜移,可应用于40Gb/s甚短距离传输的VSR5系统.