光互联网与IP over DWDM技术的演进

探讨了光互联网的支撑技术和演进策略,分析了IP over DWDM等关键支撑技术的难点与发展趋势。首先,比较分析了若干种典型的网络层次模型及其性能,指出IP over DWDM是实现未来宽带互联网的关键支撑技术;其次,分析了IP over DWDM的技术难点,指出全光信号处理和多协议标签交换技术是实现IP over DWDM的重要手段,并预言了在相关技术成熟后,光分组网技术将进一步推动光互联网的发展。     

Broadband wireless access

This article reviews the technologies and potential markets, applications, and architectures for broadband wireless access. The emergence of wireless communications for cellular systems is presented, together with its projected future evolution to mobile wideband systems. The field of broadband access systems, services, and network architectures is also covered, and then systems for broadband wireless communications for indoor local area networks and outdoor public fixed access networks are discussed. Broadband wireless access systems are emerging as a new and growing area of telecommunications, since the ability to provide access without extensive installation of copper or fiber infrastructures make wireless technology well suited for broadband services. Finally, some of the key enabling technologies, such as adaptive antennas and video compression, and the future architectural directions of broadband wireless networks are presented     

基于LiNbO3调制器的40GHz宽带调制光源的设计

介绍了基于LiNbO3电光强度调制器的40GHz宽带调制光源的设计.对其中的关键技术,如直流激光器稳态工作、调制器输出功率稳定性、频率响应预失真补偿以及整体设计等逐一加以分析,并提出解决方案.成功实现了基于LiNbO3电光强度调制器的宽带调制光源,并对该高速光源进行了一系列性能和指标测试.光源的频率响应3dB带宽达到40GHz,可用于40GHz频率范围内光电子器件频率响应特性测试,同时也满足SDH/SONET传输实验要求.     

Optical switching technology comparison: optical MEMS vs. other technologies

Optical switching technologies are very crucial to future mobile broadband all-optical IP networks. Many different optical switching technologies are currently available or under development. The main purpose of the article is to conduct performance comparisons on optical switching technologies in terms of basic performance, network requirements, and system requirements based on a literature survey. The technologies include switching based on optical microelectromechanical systems (MEMS), thermal optical switching, electro-optic switching, and acousto-optic switching technologies. Each optical switching technology has unique performance characteristics specific to the utilized optical phenomena. It might be crucial to integrate some technologies together to achieve a better solution for optical switching. Optical switching is a very hot topic attracting much research effort. Optical MEMS-based switching technology might be one of the most promising approaches at present. Many new optical switching technologies might be created in the near future. Through the impact of nanotechnology, some innovative approaches to optical switching might emerge.     

Optical services in future broadband networks

Optical transmission technology is progressing to the point where it can deliver data at rates that can strain conventional electronic broadband networks. We discuss how optical networks may play a role in relieving this strain. Different optical network architectures are discussed according to the services they provide, the technologies used to implement those services, and the geographical size of the network. We first discuss broadband network architectures and where optics might play a role in the protocol stack. We then discuss in detail the services optical networks can provide, the technologies used to implement those services, and some of the major technological limitations. Finally, we use this knowledge base to analyze the potential role of optics in WANs, MANs, and then local area networks (LANs)     

光电融合智能太赫兹的体系架构和关键技术

与广泛应用的以微波为代表的无线系统和以光纤为代表的有线系统相比,太赫兹除了其特殊的频谱特性外,人们期待太赫兹频段用于无线系统能突破微波系统的带宽限制,实现可与光纤系统相媲美的大带宽,并具有无线系统的灵活性和智能化。但如何实现宽带、智能以及具有较远作用距离的太赫兹系统,面临极大的挑战性。本文介绍了光电融合智能太赫兹的体系架构,重点讨论了基于光电融合的太赫兹源、接收检测、阵列天线以及太赫兹光电混频器等关键技术的国内外研究进展与进一步发展方向,以期解决单纯的电子学方式或光子学方式存在的难以克服的瓶颈限制。     

Optical fiber cable and wiring techniques for fiber to the home (FTTH)

NTT group’s new medium-term management strategy calls for 20 million optical subscribers by 2010, and NTT Laboratories is pushing forward to meet this goal. Before that date, an efficient optical access network must be constructed, and afterwards, when the era of mass optical communications finally arrives, the facilities and equipment supporting the network will have to be effectively operated and maintained.At NTT Access Network Service Systems Laboratories, we are developing various technologies to correspond to the massive deployment of optical broadband services. We are also developing various new technologies for efficiently operating optical access network systems that will continue to expand in the future, and to supply our customers with good services.This paper provides an overview of the new optical access network system technologies that are being developed at NTT Access Network Service Systems Laboratories to address these issues.     

Photonic transport networks based on optical paths

This paper explores the technologies that will enable a further leap forward in transport network evolution. First, requirements of the future transport network are elucidated. Existing network cost is evaluated and the viable means to reduce transport network cost are identified. It is demonstrated that optical path technologies such as WP (wavelength path) and VWP (virtual wavelength path) will play a key role in this. They enhance not only transmission capacity but also cross-connect node throughput cost-effectively by capitalizing on the wavelength routeing scheme. Optical path realization technologies focusing on optical path cross-connect systems are examined. Requirements for the optical path cross-connect system are then elucidated, and a new cross-connect system architecture is evaluated. The architecture exploits PLC (planar lightwave circuit) and other commercially available technologies suitable for large-scale production. The evaluations include cross-connect node upgradability, modular growth capability, total node cost, optical loss and switching power consumption. It is proved that the architecture has significant advantages over existing switch architectures. The optical path technologies provided in this paper will pave the way for a new transport network paradigm, a ubiquitous, bandwidth-abundant and affordable broadband ISDN.     

Very-high-speed optical signal processing

Challenges of next-generation transmission technologies are summarized in the context of creating future terabit-per-second networks. The technologies will be realized through both the separate and combined evolution of inherent lightwave capabilities along with time-, wavelength-, and space-domain optical processing techniques. Optical signal processing techniques in the tens of gigabit per second range for future high-speed transmission systems and broadband networks are reviewed     

Ingénierie des systèmes de commutation optique et des réseaux locaux à large bande sur fibres optiques : analyses et perspectives

This paper first reviews how switching evolves in the ISDN environment with emphasize placed on changes in conventionnal time-division switches, then assesses techniques and technologies usable in optical switching and broadband networks : optical space-division switching systems (architecture, technologies based on dielectrics, semiconductors, photorepactive material) and optical time-division switching (optical memories based on delay lines and on bistable components multiplexing); multiple access networks (tdma, multiple access by code) ; switching using spread spectrum (bit switching); wavelength switching (multiplexer-demultiplexer, tunable laser and filters) ; packet switching in multi-wavelength networks (broadband networks standardization, local area networks with bus, passive star or multi-star configuration).     

The Broadband Access Facility

The deployment of broadband access networks will revolutionise many aspects of society in the early years of the next millennium. Manufacturers, telecommunications providers and cable television operators world-wide are investing heavily on research into networks that provide broadband multimedia services to customers. BT has developed a prototype of a full service access network that can connect customers via optical fibre, digital subscriber line or radio technologies. This paper describes the physical implementation of the prototype network and the wide range of services that it can support.This prototype network, referred to as the 'broadband access facility' is enabling BT and its partners to understand the best access architectures for a given environment through practical testing. The network now serves as an experimental platform, that can be used for communicating broadband concepts, designing operational processes, developing management solutions and testing advanced applications.The full service access networks (FSAN) initiative is a collaboration involving fourteen of the world's leading telecommunications network operators and major equipment manufacturers. Its vision is to create a shared requirements specification for access systems supporting narrowband and broadband services. This common specification will mean that broadband network components can be developed for world markets, thus raising volumes and driving down unit costs. The common system specification is based around an ATM/SDH (asynchronous transfer mode/synchronous digital hierarchy) core network, with local optical fibre distribution via an ATM PON (passive optical network). DSL (digital subscriber line) systems maximise reuse of existing copper plant. The exact DSL system used depends upon where the optical system is terminated, e.g. in the local exchange, cabinet, kerb or home. Hence this broadband access system can support a range of access architectures — this flexibility is fundamental to the consensus achieved in FSAN.     

OFDM for Optical Communications

Orthogonal frequency division multiplexing (OFDM) is a modulation technique which is now used in most new and emerging broadband wired and wireless communication systems because it is an effective solution to intersymbol interference caused by a dispersive channel. Very recently a number of researchers have shown that OFDM is also a promising technology for optical communications. This paper gives a tutorial overview of OFDM highlighting the aspects that are likely to be important in optical applications. To achieve good performance in optical systems OFDM must be adapted in various ways. The constraints imposed by single mode optical fiber, multimode optical fiber and optical wireless are discussed and the new forms of optical OFDM which have been developed are outlined. The main drawbacks of OFDM are its high peak to average power ratio and its sensitivity to phase noise and frequency offset. The impairments that these cause are described and their implications for optical systems discussed.      

Self-assembled InAs/InP quantum dots and quantum dashes: Material structures and devices

The advances in lasers, electronic and photonic integrated circuits (EPIC), optical interconnects as well as the modulation techniques allow the present day society to embrace the convenience of broadband, high speed internet and mobile network connectivity. However, the steep increase in energy demand and bandwidth requirement calls for further innovation in ultra-compact EPIC technologies. In the optical domain, advancement in the laser technologies beyond the current quantum well (Qwell) based laser technologies are already taking place and presenting very promising results. Homogeneously grown quantum dot (Qdot) lasers and optical amplifiers, can serve in the future energy saving information and communication technologies (ICT) as the work-horse for transmitting and amplifying information through optical fiber. The encouraging results in the zero-dimensional (0D) structures emitting at 980 nm, in the form of vertical cavity surface emitting laser (VCSEL), are already operational at low threshold current density and capable of 40 Gbps error-free transmission at 108 fJ/bit. Subsequent achievements for lasers and amplifiers operating in the O-, C-, L-, U-bands, and beyond will eventually lay the foundation for green ICT. On the hand, the inhomogeneously grown quasi 0D quantum dash (Qdash) lasers are brilliant solutions for potential broadband connectivity in server farms or access network. A single broadband Qdash laser operating in the stimulated emission mode can replace tens of discrete narrow-band lasers in dense wavelength division multiplexing (DWDM) transmission thereby further saving energy, cost and footprint. We herein reviewed the1 progress of both Qdots and Qdash devices, based on the InAs/InGaAlAs/InP and InAs/InGaAsP/InP material systems, from the angles of growth and device performance. In particular, we discussed the progress in lasers, semiconductor optical amplifiers (SOA), mode locked lasers, and superluminescent diodes, which are the building blocks of EPIC and ICT. Alternatively, these optical sources are potential candidates for other multi-disciplinary field applications.     

Optical fibers reach into homes

The replacement of the standard series-connected pair of twisted copper wires that connects each home to the telephone network today by optical-fiber cabling that can handle broadband services is discussed. The technologies needed for the fiber to the home, which are dominated by such considerations as bit rates, network architecture, and power dissipation, are discussed. Various combinations of services and technologies that are currently undergoing trials are described. Future evolution into broadband networks is discussed     

Scalable, Hybrid Optical-RF Wireless Communication System for Broadband and Multimedia Service to Fixed and Mobile Users

This paper describes a system concept for providing, flexible high capacity multimedia communication that compliments terrestrial cellular communication systems, by supporting end-to-end broadband information services. A key element of the proposed concept is the use of optical HAP-HAP and HAP-satellite links using single color (SONET protocol based) or upon multicolor DWDM technology. The effectiveness of optical communication links is enhanced through the use of advanced optical fine pointing and tracking technology. A concept for a hybrid, optical-RF, HAP based wireless communication is presented and key technologies, capabilities and limitations are described. This revised version was published online in July 2006 with corrections to the Cover Date.     

用MPLS技术实现IP over WDM

提出了一种全新的高速宽带组网技术－基于MPLS的IPoverWDM网络技术,并对其进行了深入研究。这个方案在光联网技术中综合了目前先进的MPLS流量工程控制技术,特别适合于由可重构的OADM和OXC组成的以数据业务为核心的互联网络系统,而且它为最终在IP路由器上直接提供WDM复用功能铺平了道路。     

Photonic highway: broad-band ring subscriber loops using opticalsignal processing

The introduction of optical signal processing technology into transmission systems and basic experiments with optical drop/insert using bistable laser diodes are discussed. With broadband integrated services digital network (B-ISDN) architecture and technology now under study, optical signal processing (OSP) is being considered to increase network capacity and flexibility. B-ISDN will require over 40 Gb/s in the feeder loop that connects the central office and remote terminals having drop/insert function. Remote terminals will process large amounts of high-speed data. An OSP-based broadband subscriber loop photonic highway that uses a ring architecture linking photonic access nodes (PANs) that directly process optical signals is proposed. Each PAN has an optical drop/insert function and can synchronize optical frame signals using a proposed optical sampling memory. Optical drop/insert experiments confirmed the feasibility of the proposed method     

Full service optical access networks: ATM transport on passiveoptical networks

Multimedia communication has become the driving force for installing broadband systems in the public network. Different alternative solutions have been presented to realize a broadband interactive access network, such as installing optical fiber or upgrading the existing copper network with ADSL for twisted pair or hybrid fiber coax for CATV networks. Among these alternatives, optical fiber access networks are seen as the most future-safe solution. Especially, passive optical networks prove to be a cost-effective way to introduce fiber into the access network. This article presents ATM-based transport on passive optical networks, starting with a current implementation of an ATM-PON (APON) system that has already been installed for various trials. It further describes the evolution of APON systems to high-splitting, long-range PONs. The increase in both number of subscribers and distance range is discussed in combination with some specific technological issues such as upstream burst mode optical amplification. Special emphasis is placed on the work carried out within the scope of the ACTS PLANET project     

Technology 1991: telecommunications

Noteworthy trends and occurrences in telecommunication during 1990 are examined. half a dozen countries deregulated their telephone companies to admit competition in the hopes of accelerating technological development. One of the leading technologies to take off was mobile communications, particularly services based on digital transmission. A worldwide standard for the broadband integrated-services digital network (ISDN) was finally accepted, allowing worldwide compatibility for the emerging fiber-optics-based broadband ISDN systems. Meanwhile, narrowband ISDN crossed international borders for the first time, offering transoceanic service. In optical-fiber transmission, the most promising development was erbium-doped optical amplifiers, which are cheaper and simpler for long-distance communications, especially if many signals are to be multiplexed onto one fiber. In addition, investigators demonstrated a simple processor entirely based on optical logic elements and parallel optical connections through free space, which may be another significant step toward an optical computer     

制冷技术在空间红外光学系统中的应用及其发展趋势

以制冷技术在空间红外望远镜中的应用作为出发点,详细分析了目前国外最先进的三个空间红外望远镜(SIRFT、ASTRO-F、WISE)的红外光学系统所采用的制冷方式和关键技术,论述了制冷技术对空间红外光学系统的重要性及其发展趋势.通过对不同制冷方式进行优缺点分析和可行性论证,得出了发展我国空间红外光学系统制冷技术的必要性与...