Optical undersea cable systems trends

This paper reviews the evolution of undersea cable technology from the telegraph cables of the mid-nineteenth century to the optical undersea cables of today. Future systems will use optical fiber amplifiers which offer significant technical and economic advantages. Consequently, emphasis is placed on problems associated with the accumulation of small, second-order effects in long lengths of optical fiber and, specifically, their impact on the 5-Gb/s optically amplified transoceanic undersea systems scheduled to be deployed in 1995. Technology options for achieving further capacity increases, among them the use of optical solitons, and trends toward networked undersea cable systems with automatic restoration features are described     

Repeaterless undersea lightwave systems

A repeaterless undersea lightwave system connects two terrestrial locations separated by the sea without the need for undersea regeneration of the optical signal. To achieve the longest span length possible, the system combines terrestrial terminals containing superior-performance optoelectronic devices with ultrareliable undersea cable technology. The lightwave technology used to achieve cost-effective, long-span repeaterless undersea lightwave systems is discussed. This includes undersea fiber and cable, lasers and receivers, and terminal equipment. The first application of this technology, Taiwan's Tainan to Peng-Hu system, is described. The possibilities for increasing the maximum attainable span length of high-capacity repeaterless undersea systems are examined. Key elements are higher-output transmitters, more sensitive receivers, and improved optical fibers     

发展中的亚太海底光缆产品及市场

围绕着整个亚洲—太平洋地区海底光缆的应用情况及其市场因素进行了分析和讨论。内容涉及到目前的越洋海底光缆话路容量、对于此类话路的市场需求及其市场驱动原因、目前海底光缆的关键技术、近期的市场活动及其发展趋势、正在筹划中的海底光缆项目等。     

光纤外护套绝缘故障的监测

为了保障长途海底光缆的运行可靠性，需要尽早发现潜在的故障。本文介绍了一种监测海底通讯光缆外护套电绝缘性能的方法。该方法使用微控制器控制高压信号源，并同时精确控制测试电流。使用这种方法可以早期发现海底光缆的损伤。     

Recent progress in amplified undersea systems

The advent of the optical amplifiers has removed the loss limitation of the fiber in the conventional undersea systems using 3R (retiming, reshaping, regenerating) repeaters, and it has introduced new design criteria for the undersea lightwave systems. The accumulation of the small impairment factors that was negligible in the conventional system becomes significant to determine the transmission performances of the amplified system. The fiber nonlinearity is a distinctive limitation factor that dominates the transmission performance of the amplified system, although it was not a limitation factor in the conventional system. This paper describes the recent progress of the undersea lightwave cable systems employing optical amplifier repeaters. The limitation factors and the polarization dependent characteristics of the amplified system are described. The system demonstrations with conventional IM-DD technology are presented using both recirculating loop and straight fiber transmission line. The system maintenance method is also explained briefly. Future technologies adopting the WDM or the optical solitons are also discussed     

海底光缆网络远程供电技术研究

传统的有中继的海底光缆传输系统由端站的远程供电设备（PFE）对中继器等有源设备进行供电,而海底光缆网络的远程供电系统更加复杂,为此在介绍了传统海底光缆传输系统的远程供电系统的基本原理后,重点对海底光缆网络的两种远程供电方式——串联和并联供电方式做了分析,分别对其供电效率进行了计算,并做了比较。     

The SL Undersea Lightguide System

A digital optical fiber undersea cable system targeted for transatlantic service in 1988 is now under development at Bell Laboratories. The system uses single-mode fibers to carry data at a bit rate of 280 Mbits/s. Using digital speech compression techniques, a total system capacity of over 35 000 two-way voice channels can be realized. With laser transmitters at 1.3 μm, repeater spacings are expected to exceed 35 km. This paper discusses system parameters, repeaters, fiber and cable design, terminal equipment, and system measurements.     

Effect of natural radioactivity on optical fibers of underseacables

For undersea cables radiation doses between 2.5 and 25 rad are to be expected during a working life of 25 years. The majority of previous investigations of the radiation sensitivity of optical fibers, however, apply dose rates ≳1 rad/s and total dose values ≳3×10 ³ rad. The present paper describes ⁶⁰Co irradiations of a Ge-doped single mode fiber with dose rates between 10 ^-4 and 20 rad/s. Expected loss increase of an undersea optical fiber cable at 1550 nm wavelength with a temperature of 2°C is derived by three different methods. The most comfortable and reliable one, the `dose rate transformation method', yields, for example, a loss of only 0.0244 dB/100 km after 25 years of irradiation with a dose rate of 0.4 rad/s. This method could be the basis of a standard test procedure for the effect of natural radioactivity on optical fibers for very long repeaterless terrestrial and undersea cables     

Physical Design of the SL Repeater

SL undersea fiber-optic cable allows for the installation of multiple pairs of fibers in the same cable. Using the same high-pressure repeater housing as used in previous undersea systems (and thereby accruing the benefits of no tooling costs and proven handling methods), we are able to mount six optical regenerators. This group of regenerators will dissipate approximately 30 W in service. Previous undersea repeaters dissipated approximately 8 W and achieved a maximum internal temperature of 5° C above the repeater ambient. That might imply a temperature of 20° C above ambient for the SL repeater, which would be intolerably high for reliable undersea performance and longevity. The main thrust of the SL design was to lower this temperature rise. We have achieved a design which is capable of dissipating 30 W with only 4°C temperature rise. This paper describes the design steps necessary to achieve this result and examines the overall repeater structure showing its special design features for accommodating fiber sealing and jointing.     

Undersea fiber optic cable communications system of the future: Operational, reliability, and systems considerations

The systems and operational requirements, reliability, and cost estimates for several undersea fiber optic cable communications systems of varying capacities, data transmission rates, and link distances are analyzed in detail to highlight relevant design tradeoff parameters. It is shown that systems with a high data rate per fiber are more economical and reliable than low data rate systems with multiple fibers. This study concludes that undersea optic cable systems can soon provide reliable broad-band digital services.     

The FLAG cable system

The Fiberoptic Link Around the Globe (FLAG) cable system is a 10 Gb/s synchronous digital hierarchy (SDH) based undersea fiber optic network. When fully operational, FLAG will connect 12 countries with over 120000 voice channels via 27000 km of mostly undersea cable. FLAG will incorporate a new generation of undersea fiber optic system that uses erbium-doped fiber amplifiers and will be jointly supplied by AT&T Submarine Systems Incorporated (SSI) and KDD-Submarine Cable Systems (SCS) Inc. When completed, FLAG will meet or exceed all relevant international performance standards, have greater reliability and availability than previous systems in the region, and conform to all ISO 9000 quality standards with respect to design, development, production, installation, and service     

Review of the Depressed Cladding Single-Mode Fiber Design and Performance for the SL Undersea System Application

High-capacity undersea cable systems based on optical transmission over single-mode lightguides offer tremendous economic advantage over coaxial cable technology due to their combined high-bit-rate long repeater spacing potential. However, very stringent requirements for the lightguide transmission medium properties must be met in order to realize the performance goals of such systems. This paper will review the depressed index cladding single-mode fiber design and its resultant performance. The ability to simultaneously realize excellent optical, mechanical, and dimensional properties in lightguides of this type fabricated using the Modified Chemical Vapor Deposition (MCVD) process has resulted in their use in the AT&T SL system to be used in TAT8.     

Applying WDM technology to undersea cable networks

WDM technology is now being applied to international undersea fiber optic cable networks in order to provide enhancements such as increased network capacity and greater network flexibility. This article looks at what WDM technology can provide, the progress being made, and the special challenges in its application in undersea networks. We then describe several international undersea networks that, when completed by the end of 1999, will use WDM technology and will serve as a major part of the global undersea fiber optic infrastructure connecting the world     

Optical amplifiers transform long-distance lightwavetelecommunications

Optical amplifiers and wavelength-multiplexing technology are transforming lightwave communications by providing cost-effective upgrades that will increase immensely the transmission capacity of long-distance telecommunications networks. A new generation of undersea cable systems using fiber optical amplifiers as repeaters has been developed for transoceanic applications, yielding a capacity almost ten times larger than conventional systems using opto-electronic regenerators. Terrestrial long-haul networks will benefit significantly from amplified wavelength-multiplexed transmission systems designed to access the large inherent bandwidth in the installed fiber. Successful deployment of these advanced systems requires a thorough understanding of optical amplifiers and the optical fiber medium, as their requirements interrelate through optical bandwidth, noise, dispersion, optical nonlinearities, and their impact on signal transmission. While the first commercial WDM amplified lightwave systems are deployed for point-to-point applications, optical transparency and wavelength multiplexing will be exploited for networking leading to the higher functionality and improved cost-effectiveness expected of photonic networks     

海底光缆通信技术

结合设计实例，介绍了第三代海底光通信的最新技术，为海底光缆通信系统工程设计提供了思路。最后，探讨了海底光缆通信的发展趋势。     

1.3 ?m, 400 Mbit/s undersea optical repeater sea trial

A sea trial of a 1.3 ?m, 400 Mbit/s undersea optical repeater1,2 connected with a 1.3 km-long undersea optical cable was conducted in Sagami Bay at about a 700 m depth in January 1981. Stable performance for the repeater was confirmed, as it withstood such external mechanical forces as heavy tension, water pressure, vibration, shock and extreme temperature change during laying and recovering.     

A 150-km Repeaterless Undersea Lightwave System Operating at 1.55um

A repeaterless undersea cable system spanning 150 km between a shore site and an off-shore floating platform is to be installed early in 1985. The system uses single-mode fibers to carry data at a line rate of 3.088 Mbit/s. Laser transmitters operating at 1.55 μm and p-i-n receivers complete the optical system. This paper discusses system parameters and performance, and both terminal and undersea equipment.     

A 150-km repeaterless undersea lightwave system operation at 1.55 µm

A repeaterless undersea cable system spanning 150 km between a shore site and an off-shore floating platform is to be installed early in 1985. The system uses single-mode fibers to carry data at a line rate of 3.088 Mbit/s. Laser transmitters operating at 1.55 μm and p-i-n receivers complete the optical system. This paper discusses system parameters and performance, and both terminal and undersea equipment.     

光缆进线室列架设计之新理念

根据目前光缆进线室存在的问题，提出了光缆进线室设计的新理念，详细描述固话铜缆上线列架与光缆上线列架的不同之处，并对进线室的大小、上线列架的方式进行探讨．对双伸臂式列架进行全面的介绍。     

Technology 1993-telecommunications

Significant events during 1992 are highlighted. Communication technologies began merging, with cable TV offering telephone service and telecommunication companies offering TV. Wireless personal communication systems (PCSs) got the green light when the 1992 World Administrative Radio Conference designed frequency bands for future mobile communications services, with provisions for such services to be handled via low-Earth-orbiting satellites, and the US Federal Communication Commission allocated frequencies in the 2 GHz band to the deployment of several emerging technologies, including PCSs. Multimedia communication took off with the introduction of new services. In optical communication, erbium-doped fiber amplifiers were installed in the world's longest repeaterless undersea link. Strained-layer multi-quantum-well lasers received increasing attention, due to the improved system and device properties they offer. Research on cheap optical interconnects and packages gained momentum