Undersea fiber cable technology

Compared with the conventional coaxial undersea cable systems, an optical fiber undersea cable system has a great technical and economical advantage. It is also suitable for digital transmission. In this paper, the optical fiber undersea cable technology (including optical fiber cables and repeaters), which is now in the research and development stage in several countries, is reviewed.     

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     

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     

Subscriber optical fiber cable transfer splicing system usingmechanically transferable connectors

An optical fiber cable transfer splicing system is developed for use in removing or changing optical fiber cables. The system enables rapid transfer from existing optical fiber cables to newly installed ones. The transfer is carried out synchronously using two mechanically transferable connectors which terminate the optical fiber cables at two different points, such as manholes. Before the transfer splicing, the system identifies a fiber ribbon in order to avoid mistransfer. A transfer time of less than 30 ms was achieved. The fiber ribbon was identified with a loss, from an identification light source to an identification point, of 35.5 dB. With this system, cable transfer can be faultlessly carried out with only a slight interruption to working transmission systems and circuit quality degradation is suppressed     

室内光缆的探讨

随着光纤光缆的大量使用,光缆进入建筑物内将不可避免,于是室内光缆应运而生并被迅速普及,成为光缆领域未来研究发展的热点,其市场前景非常广阔。室内光缆要求结构简单、价格便宜、易于分线和连接、阻燃等,因此有必要对室内光缆的诸多方面,包括结构、材料、标准和检测方法等进行研究。对室内光缆进行了简要的介绍,对室内光缆的各种典型结构及应用进行讨论,并对室内光缆的生产设备、标准和检测方法作了简单分析。     

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.     

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     

Present status and outlook of line transmission systems in China

The various line transmission media, including open wires, symmetrical pair cables, coaxial cables, and optical fiber cable, that are used in the different regions of China are described. Both analog transmission systems and the newer digital transmission systems are discussed. The standardized physical transmission media deployed throughout China-symmetrical pair cables, coaxial cables, and optical fiber cables-are also discussed     

光缆在线监测系统

近几年来光缆在电力系统的应用越来越普及，电力系统的通信、自动化、维护等越来越依赖高可靠、高性能的光纤传输。但在实际应用中，由于受外力及光缆本身质量等因素影响，光缆很容易遭到破坏，从而影响光缆的传输质量。光缆在线监测系统能在光缆遭到破坏时迅速确定光缆的故障点，为光缆故障修复提供宝贵的时间。     

光纤通信工程光纤光缆的验收

给出了光纤光缆产品的主要技术指标和测试方法,讨论了光纤光缆主要技术特性和光纤通信系统申通信容量、中继距离、接续损耗的关系,阐述了光纤光缆验收的基本原则和验收的一般方法。     

Recent developments in hermetically coated optical fiber

Recent progress on the development of hermetically coated optical fiber is presented. This fiber provides improved fatigue resistance; high usable strength; and excellent resistance to hydrogen permeation, 25-90°C water, and corrosive chemicals such as hydrofluoric acid and boiling sodium hydroxide. These attributes make the hermetically coated fiber an excellent candidate for use in undersea cables and other special applications where a harsh environment prevails     

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.     

光缆老化模型浅析

光缆在电力系统中承担着非常重要的作用,其老化状态直接影响电力系统的使用 安全和运行可靠性,因此对于光缆老化检测技术的研究逐渐受到了广泛的重视? 通过对光缆特性进行分析后,重点介绍了3种老化预测模型,寻找出光缆在不同 环境中的老化规律,从而有效对光缆剩余寿命进行预测?     

Studies on designing of submarine optical fiber cable

This paper describes important studies necessary to design submarine optical fiber cables. These include a study for deciding the optimum single-mode fiber parameters to suppress losses during cabling, cable laying, and so on. It also includes a study on the necessary fiber proof test conditions to prevent fiber breakage during cable handling, that is, during cable laying and recovery and to assure long-term fiber reliability. Submarine optical fiber cable sea trial results are also stated for cables designed applying these studies.     

光纤光缆最新进展

本文对国内外光缆的最新进展进行了综合分析。针对国内现状,对大芯数光缆、接入网用光缆、ADSS光缆提出了若干建议。同时,还对涉及光纤光缆测量方面的一些新技术作了简单的介绍。     

Measurement of longitudinal strain in optical fiber cables during installation by cable ploughing

This paper reports a series of experiments in which a number of optical fiber cables were installed using cable ploughing equipment. The elongation of fibers in these cables was monitored during installation in order to assess whether excessive strain levels were encountered. The experiments confirmed that optical fiber cables can be satisfactorily installed using such techniques, and that residual strain levels were sufficiently low that the fiber lifetime was not prejudiced. It was found that optical fiber cables that are flexible and in which fibers are loosely housed can be installed with lower strain levels than other cables. A range of cable-ploughing equipment was used, and equipment which controlled the rate at which cable was fed from the cable drum was found to yield the best performance.     

Design and performance of ultra-high-density optical fiber cable with rollable optical fiber ribbons

This paper proposes a novel ultra-high-density optical fiber cable that employs rollable optical fiber ribbons. The cable has great advantages in terms of cable weight and diameter, and fiber splicing workability. Moreover, it will be easy to install in a small space in underground ducts and on residential and business premises. The structural design of the rollable optical fiber ribbon is evaluated theoretically and experimentally, and an optimum adhesion pitch P in the longitudinal direction is obtained. In addition, we examined the performance of ultra-high-density cables with a small diameter that employ rollable optical fiber ribbons and bending-loss insensitive optical fibers. The transmission, mechanical and mid-span access performance of these cables was confirmed to be excellent.     

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     

Loop-network configuration and single-mode optical fiber cable technologies for subscriber network

This paper will discuss optical fiber cable distribution networks for accomodating the immediate introduction of optical subscriber networks. The concepts of cable distribution system design, the maintenance systems and the cables and jointing technology for supporting these systems will be discussed. The results of experiments using related technology will also be discussed.     

光纤通信在高校安全防范系统中的应用

概述了光纤通信在高校安全防范系统中的应用.对高校技术防范系统的特点,光缆的选择,光缆路由的设计,以及光纤通信的实施方案等进行了阐述.对构筑同等规模的安全防范系统具有一定的参考作用.