光纤通信空分复用技术研究进展分析

带宽容量需求的快速增长驱动光纤通信技术不断演进,目前多芯光纤复用、少模光纤复用、少模多芯光纤复用和轨道角动量模式复用等空分复用技术成为业界的关注焦点.基于此,对空分复用技术涉及的新型光纤设计、模式转换与控制、信道复用/解复用、光放大等关键技术及其研究进展进行了分析,同时对其技术特征进行了对比总结,并对光纤通信空分复用技术目前存在的问题和未来发展的应用前景进行了探讨和展望.     

用于大容量光传输系统的新型光纤

多媒体和数据应用程序的快速扩展,驱动骨干网的带宽需求量以前所未有的速率增长。骨干容量增长的同时也给数据中心的带宽和互联带来了更多的挑战。目前光纤制造厂商正不断改善光纤的性能,以满足长途和短距离应用的需求。短期内通过改进传统光纤技术虽然可增加系统容量,但研究表明,单模光纤的传输容量正快速接近香农理论极限。采用空分复用的光纤技术可以克服该限制,为未来的容量增长提供新的解决方案。在本文中,将讨论提高光纤传输系统容量的新型光纤。对应用于长途传输的常规光纤而言,先进的数字信号处理可对色散和偏振模色散等损伤进行完全补偿,因此光纤的衰减和有效面积成为可进一步优化的参数,讨论以上两个参数的品质因数,总结超低损耗和大有效面积光纤的最新研究成果。对于短距离应用,回顾提高多模光纤带宽的方法,讨论多模光纤的发展趋势。对于下一代光纤,重点研究可实现空分复用技术的多芯和少模光纤,该技术可增加系统容量一个数量级。阐述多芯和少模光纤的设计思路,总结该技术的最新进展,最后讨论使用多芯和少模光纤所面临的主要挑战。     

多芯光纤扇入扇出技术发展现状及展望

基于多芯光纤的空分复用是解决当前光通信传输容量瓶颈的最有效方法之一,多芯光纤扇入扇出(FIFO)技术是实现多芯光纤空分复用系统的关键,它用于实现单个多芯光纤到多个单芯光纤的光耦合功能.文章总结了近十年来多芯光纤FIFO器件和装置的方法,将它们归纳为熔融、光纤束、自由空间光和三维集成波导4种类型,分析并比较了几种类型器件...     

多芯光纤光栅写入技术研究进展

为了进一步增加光纤通信容量,作为空分复用实现方案之一的多芯光纤技术吸引了人们越来越多的研究兴趣.与此同时,基于多芯光纤的各种新型有源、无源光器件也不断涌现.其中,多芯光纤光栅,由于结合了多芯光纤与光纤光栅的独特优势,为新型全光纤器件的设计和应用提供了多种可能,在光纤通信、光纤传感、光纤激光器等领域具有广泛的应用空间.本...     

超高速率超大容量建设用光纤技术

超高速率、超大容量、超长距离的光纤传输技术是解决通信网未来带宽需求的关键技术之一.在系统单信道速率向100Gb/s甚至1 Tb/s演进过程中,传统的G.652.D低水峰光纤仍将发挥重要作用.超高速率超大容量光纤通信在器件、调制格式、接收检测方式等方面的创新,对通信光纤的性能提出了新的要求.进一步降低光纤损耗可以延长中继距离;大有效面积光纤可以提高注入信道光功率,降低非线性效应,提高链路光信噪比(OSNR).多芯光纤和少模光纤,可以增加空分复用维度,是未来突破光纤香农极限的研究方向之一.     

短距离弱耦合空分复用实时光传输技术

短距离光纤传输系统的容量扩展受到越来越广泛的关注。空分复用光传输技术提供了纤芯和模式两个新维度，可以大大提升单根光纤的传输容量。然而空间信道间的串扰严重限制了空分复用技术的实用化。首先研究了弱耦合空分复用光纤，通过在纤芯引入环形折射率微扰的方法实现了模式之间的有效分离；其次，提出了一种可以处理非圆对称简并模式的全光纤复用/解复用器件以及低插损、低串扰扇入扇出器；在此基础上，使用低成本商用强度调制直接检测光模块，实现了短距离弱耦合模分复用及多芯少模复用实时光传输；最后对空分复用实时光传输技术进行了展望。     

多芯掺铒光纤的制备及其放大性能

空分复用技术被认为是未来实现光纤通信容量升级扩容的关键技术。传输距离是决定空分复用系统应用场景的关键,空分复用系统中信号的传输离不开放大器对损耗的补偿,因此,基于多芯掺铒光纤的空分复用光放大器是空分复用技术走向实用化的核心器件。本文基于改进的化学气相沉积技术结合打孔法制备了七芯掺铒光纤,并搭建了纤芯独立泵浦多芯光纤的放大系统,测试了七芯掺铒光纤的放大性能。在输入信号为0 dBm,泵浦光功率为350 mW的条件下,测得七芯掺铒光纤纤芯在C波段(1526～1566 nm)的平均增益为14 dB,平均噪声指数小于6 dB,不同纤芯间的增益差小于5 dB。     

用于空分复用的模式复用技术研究

空分复用技术作为克服单模光纤通信系统容量局限的一种可能解决方案近年来受到日益广泛的重视,具有多种实现方案,例如采用多芯光纤、MIMO技术(Multiple-Input MultipleOutput)、基于多模光纤、空间光学元件的模式复用等。针对空分复用技术,分析了几种模式复用解决方案,阐述原理的同时,介绍了各方案的最新实验结果,最后对各种方案的特点进行了评述。     

少模光纤中模式选择性激励技术北大核心

基于少模光纤的模分复用系统能继续提高光纤通信系统的传输容量,目前已成为全球的研究热点。在介绍了少模光纤设计后,文章对3种模式选择性激励技术(偏移注入、长周期光纤光栅和空间光调制)的激励机制、特点及实现进行了研究,并重点介绍了基于空间光调制的模式选择性激励技术。     

基于少模光纤布拉格光栅的模分复用系统实验研究

本文提出了一种基于少模光纤布拉格光栅(Few-mode FBG)的模分复用通信系统,阐述了基于少模光纤布拉格光栅的模分复用/解复用原理,建立了2×2的模分复用实验系统,分别利用LP01和LP11模作为独立信道,实现了1.25 Gbps和622Mbps两路伪随机序列(PRBS)的10km传输实验,给出了传输后的眼图,分析了当激光器波长为1549.228nm时,实验系统的误码特性.实验验证了基于少模光纤布拉格光栅的模分复用通信系统的可行性,为进一步实现长距离高速率的模分复用通信奠定了实验基础.     

光线路自动倒换保护(OLP)系统建设方案

为有效地预防和压缩光缆传输系统故障,提高光通信网抗阻断、高可靠、安全、抗灾害能力,提高长途光缆维护质量,光纤自动监测倒换系统是实现这一责任目标的重要的现代化维护手段。实现光缆网的自动监测倒换系统,从而在通信光缆线路设备大幅度增加,原有的线路维护技术人员又不能同幅增员的情况下,确保巨额投资建成的光缆传输网高质、高效、安全地运行。     

Terahipas: a modular and expandable terabit/second hierarchicallymultiplexing photonic ATM switch architecture

A terabit/second hierarchically multiplexing photonic asynchronous transfer mode (ATM) switch network architecture, called Terahipas, is proposed. It combines the advantages of photonics (a large bandwidth for transport of cells) and electronics (advanced logical functions for controlling, processing, and routing). It uses a hierarchical photonic multiplexing structure in which several tens of channels with a relatively low bit rate, say 2.4 Gb/s, are first time-multiplexed on an optical highway by shrinking the interval between optical pulses, then a number of optical highways are wavelength-multiplexed (or space-division multiplexed). As a result, the switch capacity can be expanded from the order of 100 Gb/s to the order of 10 Tb/s in a modular fashion. A new implementation scheme for cell buffering is used for eliminating the bottleneck when receiving and storing concurrent optical cells at bit rates as high as 100 Gb/s. This new architecture can serve as the basis of a modular, expandable, high-performance ATM switching system for future broad band integrated service digital networks (B-ISDN's)     

基于边缘云计算的光纤无线网络优化设计

为了提升网络边缘数据处理能力,满足终端大带宽和低时延的要求,构建了基于边缘基础设施的云计算平台,设计了具有动态带宽调整的光纤网络模型。提出了一种基于边缘云计算的时序优化算法,并将其应用于光纤无线网络。通过OPNET软件仿真分析了时序优化算法的传输时延均值,结果显示,优化后最大时延为43.1 ms,仅为传统方法的34.2%。实验对局域网内多个终端之间的数据通信进行分析,讨论了三种算法的传输能效、光纤信道利用率及传输能耗。实验结果显示,采用时序优化算法的测试结果具有明显改善,其传输能效提升了近1倍,边缘云数据传输时延均值信道利用率提升了约6.2%,网络传输能耗均值最优。该光纤无线网络模型及其优化算法在传输时延、信道利用率以及网络能耗方面具有明显提升。其在提升光纤通信链路选择及边缘端数据交互中具有一定的优势。     

Reconfigurable OADM and OXC designed by a new optical switch

A new dynamically selective optical add/drop multiplexer (OADM) and optical cross-connect (OXC) configuration for dense wavelength division multiplexed (DWDM) networks are proposed. The selective devices are based on fiber Bragg gratings (FBGs), single-sided micro-mirror optical switches (OSWs), and optical circulators (OCs). They are flexible, expandable, and high capacity in DWDM networks if the basic units are cascaded in series. In this paper, fiber collimators in coupling are analyzed in order to characterize the insertion loss and output power equalization in OADM and OXC. “Off-the-shelf” DWDM communication products are used for analysis; as a result, the main insertion loss in the system comes from circulators while the maximum insertion loss deviation comes mainly from FBGs and micro-mirrors. As compared to the other existing reconfigurable OADMs and OXCs, the number of mirrors in the optical switch could be dramatically reduced. The reliability of optical switch operation, therefore, can be enhanced.     

Coherent quadrature phase shift keying optical communication systems

Coherent optical fiber communications for data rates of 100 Gbit/s and beyond have recently been studied extensively because high sensitivity of coherent receivers could extend the transmission distance. Spectrally efficient modulation techniques such as M-ary phase shift keying (PSK) can be employed for coherent optical links. The integration of multi-level modulation formats based on coherent technologies with wavelength-division multiplexed (WDM) systems is vital to meet the aggregate bandwidth demand. This paper reviews coherent quadrature PSK (QPSK) systems to scale the network capacity and maximum reach of coherent optical communication systems to accommodate traffic growth.     

Transmitting time‐critical data over heterogeneous subnetworks using standardized protocols

Current communication networks consist of subnetworks of different types. Therefore a common network protocol has to be used for the transmission of data in such a heterogeneous network. Since some time the requirement of mobility in communication networks is showing up. For that reason wireless networks are playing an increasing role as subnetworks. On the other hand there is the need for multiplexed transmission of time-critical and non time-critical (normal) data within a heterogeneous network. In this paper we discuss the problem of multiplexed transmission of time-critical and of non time-critical data over a wireless type subnetwork using a common standardized network protocol. Many of the available wireless subnetworks are of low or medium transmission speed and guarantee a fixed transmission bandwidth at the access point. We describe a mechanism to transmit time-critical data in such a type of subnetwork using a connectionless transport and a connectionless network protocol. The concurrent transmission of non time-critical data using a connection oriented transport and the same connectionless network protocol is assumed to be of lower priority; it is scheduled in a way to fill the remaining capacity, which has not been reserved for the transmission of time-critical data. In our discussion we concentrate on the standardized ISO/OSI protocools CLNP as connectionless network protocol, CLTP as connectionless transport protocol and TP4 as connection oriented transport protocol. We propose a header compression protocol and a fragmentation protocol for use on low bandwidth subnetworks. This revised version was published online in June 2006 with corrections to the Cover Date.     

光纤通信网络在高速数据采集系统中的应用

基于光纤通信网络对一种高速数据采集系统进行了设计。通过多路数据采集方式,并与光纤通信网络相结合,使得高速数据采集能力得到大幅提高。该系统主要由处理系统、采集模块及光纤网络共同构成,光纤通信网络前端采集模块在模拟滤波、采样完成后,通过处理器实现信号的传输。此外,通过光数据采集系统实验,证明了在高速数据采集系统中应用光纤通信网络能实现速率在10 Gbit·s-1以下的光数据接入采集。     

Acoustooptic tunable filters in narrowband WDM networks: systemissues and network applications

The system issues and network applications of acoustooptic tunable filters (AOTFs) are discussed. AOTFs are thought to be attractive system components in dense wavelength-division multiplexed (WDM) networks because of their broad continuous electronic wavelength tunability and narrow filter bandwidth. Their unique multiwavelength filtering capability adds a greater dimension of flexibility to network design. The characteristics of the AOTF are reviewed from a system viewpoint and the performance and capabilities of bulk-devices, integrated-optic devices, and fiber-based devices are discussed and compared. Three network applications using the acoustooptic tunable filters are described. The first application is as wavelength-tunable receivers or taps for local users in a subscriber loop distribution network. The second is as multiwavelength tunable receivers in a broadcast local-area cross-connect for packet communication with very-high-throughput data rate. The third is as wavelength-selective space-division switch fabric for routing and cross-connect between central offices. Future prospects and various issues for future research are also discussed     

光传输设备在电力系统通信中的应用

随着输电网络的进一步发展,电力系统的通信网也在逐步完善,这对电力系统的运行和维护提出了新的要求。在这些技术中,光传输设备的应用范围越来越广。光纤传输装置的作用是将通信信号转换为适当的电信号,使其在光纤信道中有效地传播。与常规电子通信装置相比,光传输设备的通信容量更大,传送条件更稳定,数据安全性能更好。因此,光传输设备越来越受到重视,得到了越来越多的应用。文中从目前的电力通信网络所支持的服务模式出发,对各种服务方式的需求进行了分析,并对 SDH光传输网络的需求进行了探讨。     

Performance Evaluation of Symmetric 8 × 10 Gbps TWDM-PON Incorporating Polarization Division Multiplexed Modulation Techniques Under Fiber-Impairments

Today’s access networks are in high demand to fulfill the high bandwidth requirement because of extensive improvement in high transmission rate applications for cloud computing, big data analytics, and other next-generation 5G smart applications. This exponential growth of high capacity and broadband access technologies comprise an essential trend in the development of a passive optical network (PON) access network. In this paper, 80/80 Gbps time wavelength division multiplexing PON (TWDM-PON) incorporating polarization division multiplexing (PDM) based Mach–Zehnder modulator (MZM) and electroabsorption modulator (EAM) techniques have been proposed. The performance of the system consisting of different polarized multiplexed modulation techniques is investigated in both downstream and upstream data transmission for variable transmission distance and received optical power in terms of bit error rate (BER), eye diagrams, power budget (PB) and receiver sensitivity. The results show that the 4?×?20/20 Gbps PDM-EAM modulated signals over 100 km fiber distance at ??60 dBm RS and 70 dB PB are successfully transmitted under fiber non-linearities. The proposed TWDM-PON system provides a next-generation long-reach access network from urban to rural areas.