网络中的TrueWave RS光纤和其他单模光纤的混合

在今天已建成的网络中可发现各种类型的单模光纤。象IEC和ITU这样的标准组织已认可了四种单模光纤：色散非位移光纤(G.652)、色散位移光纤(G.653)、截止波长位移光纤(G.654)和非零色散光纤(G.655)。此外，有两种G.652光纤(传统的和低水峰)，和无数的商用G.655光纤(小的、中等的和大的有效区域；低的、中等的和高的色散斜率；负的和正的色散)，有时会在一个网络中使用。当将OFS公司的TrueWave RS光纤同色散非位移和其他非零色散光纤混合时，应评价几个方面的指标，包括：(1)接续损耗，(2)单向OTDR异常，(3)链路色散，(4)链路色散斜…     

G.652和G.655光纤在DWDM系统中的应用

G．652光纤又称常规单模光纤或色散未位移单模光纤;G．655光纤又称非零色散位移单模光纤。到目前为止,我国的通信网主要采用G．652和G．655光纤。     

不同类型光纤对CWDM系统性能的影响

文章比较了目前应用于粗波分复用(CWDM)系统的各类光纤的性能,结合光纤在系统测试中的表现情况对各类光纤的优缺点进行了评价.肯定了标准单模光纤和非零色散位移单模光纤应用于CWDM系统的可靠性,分析了G.652C/D和G.655B/C两类低水峰光纤支持全频谱CWDM传输的优势和在网络升级中的应用潜力,同时与色散位移单模光纤、负色散 (平坦)光纤等非主流光纤的性能作了比较.     

DCF在长距离光纤传输系统中用于色散补偿的局限性

本分析了现有DCF进行色散补偿存在的缺陷,并对温度由-4℃～60℃变化时色散补偿光纤(DCF)、普通单模光纤(G．652)和非零色散位移光纤(G．655)在S、C和L波段的色散和色散斜率进行长时间测试,指出色散斜率不匹配是限制现有DCF在未来高速、大容量光纤通信系统中应用的主要障碍之一。     

城域网中真波光纤和全波光纤的应用

自1993年朗讯科技发明真波光纤以来,G.655非零色散位移光纤逐渐取代了G.652单模光纤,成为美国陆上长途网络的主流光纤。然而在过去一段时间里,由于法律规定的限制,在美国像SBC、BELLSOUTH等一些本地运营商并没有建没长途传输网,他们将主要业务范围集中在本地业务。在这些本地运营商的网络中,中央局(节点)之间的传输距离一般较短(典型是7km左右)。在这种应用中,G.652单模光纤的高色散并不像在长途网那样关键,所以本地运营商在过去几年中一直使用G.652单模光纤。     

G.655光纤与其它单模光纤在同一个网络中的混用研究

随着话音业务、数据业务以及可视信息业务的不断增长,光纤通信因其速度快、传输质量好以及高带宽等优点恰好适应了这种业务量的增长,从而得到了迅猛发展。目前市场上常用的光纤有G.652光纤和G.655光纤两大类,而G.652光纤又包括传统单模光纤和全波光纤（G.652.C）两种。G.655光纤的种类就更多了,包括:小的、适中的或者大的有效面积光纤;低的、适中的或者高的色散斜率光纤;负的或者是正的色散光纤。     

DWDM系统结构的优选

当今光传输通信网络，无论是骨干长途网、本地城域网还是用户接入网，大多数都以密集波分复用(DWDM)为平台，基于DWDM的光传送网构成了整个通信网的基础物理层。DWDM技术的迅猛发展，得益于光纤承载介质技术的不断创新，光纤由过去标准单模光纤(G．652)，色散位移光纤(G．653)，到非零色散位移光纤(G.655)，实现了新型的全波光纤(All—wave Fiber)。由于光纤制造工艺的改进，基本消除了光纤制造过程中引入的水分，常规光纤     

G.65~*光纤

近年来,光通信网络已成为现代通信网的基础平台,因而我们敷设的光缆必须能够满足超高速系统要求。从八十年代后,光纤通信逐步从短波长区向长波长区、从多模光纤向单模光纤转移和发展。目前,在光纤骨干传输网中,限制光纤传输的主要因素是:(1)色度色散;(2)偏振模色散;(3)光纤的非线性。根据ITU—T建议,分别先后出现了G.651、G.652、G.653、G.654、G.655等不同类型的光缆,下面具体简介一下。     

用于不同层次通信网络最新光纤

首先简单的阐述了不同层次的通信网络的特点。其次,介绍了宽带光传输非零色散位移单模光纤、色散补偿单模光纤、无水峰纯硅芯非色散位移单模光纤、宽工作波长多模光纤和塑料光纤等最新光纤特点和性能指标。     

骨架式非零色散位移光纤带光缆的研制

随着刚络技术的飞速发展,通信容量正在陕速增长,从而促使波分复用技术不断进步。密集波分复用(DWDM)系统的开通大大增加了光纤通信系统的传输容量。目前,国内传输速率为10Gbit／s密集波分短用系统已经投入商用,不远的将来,更高速率的传输系统也会投入应用。在波分复用系统中,为了克服色散对通信距离及速率的限制,必须对光纤进行色散补偿。密集波分复用系统中使用非零色散位移单模光纤(NZ-DSF,G655),不仅克服了G．652光纤在1550nm披长的高色散值对传输系统限制的缺点,也消除了G653光纤在1550nm波长零色散而造成的非线性效应。     

Microwave fibre optic thermometers

Luxtron, has released a new m600 Series of OEM thermometry instruments that provide precise and repeatable in-situ monitoring of food temperatures in microwave environments. One, two and four channel versions of the m600 are offered in a compact DIN-rail module, measuring only 75mm × 105mm × 45mm, and offering both 0–10V (−100°C to 300°C) analogue and serial RS232 ASCII outputs as standard.This is a short news story only. Visit www.three-fives.com for the latest advanced semiconductor industry news.     

Beamforming fibre optic sensor

An optical sensor using a twisted birefringent single mode fibre embedded in or cemented to the outside of a hollow cylinder is shown to exhibit an acoustic response which depends on the frequency and propagation angle of the incident wave. Experimental results verifying the predicted behaviour are reported.     

Miniature fibre optic polariser

At low-loss fibre optic polariser is fabricated by embedding a thin polarisation-splitting chip in a single-mode fibre. The insertion loss and extinction ratio were 0.6 and 22 dB respectively, at a wavelength of 1.3 μm. The device size was only 4 mm in diameter and 25 mm in length     

Polarisation-insensitive fibre optic Michelson interferometer

A polarisation-insensitive fibre optic Michelson interferometric sensor configuration is demonstrated. The approach is based on the use of birefringence compensation in a retraced fibre path using Faraday rotator mirror elements.<>     

Single-mode fibre optic directional coupler

A technique is presented for the fabrication of single-mode fibre optic directional couplers. Properties of couplers made using this technique include stability and durability, continuous tunability to a power transfer of 70%, less than 10% loss, high insensitivity to polarisation, and high directivity.     

Bidirectional fibre optic loop-structured network

A basic bidirectional fibre optic loop-structured network configuration which provides an automatic recovery mechanism against a line failure and employs WDM-TDMA techniques for signal multiplexing is presented. Experimental results of a prototype of such a network are also described.     

Satellites versus fibre optic cables

This paper compares the capacities and costs of the new fibre optic submarine cables and the forthcoming INTELSAT VI satellites. The results indicate that, contrary to generally accepted beliefs, satellites are cheaper than fibre optic cables on a per circuit point-to-point basis. Moreover, satellites are shown to possess the advantage of superior overall connectivity capability, in addition to simple point-to-point capacity. This is expected to be very important in the choice of future cost effective facilities.     

Monomode fibre optic vortex shedding flowmeter

The use of a monomode optical fibre sensing element in the measurement of flow velocities by an interferometric technique is described, in which the operating principle is the flow induced oscillation of the fibre caused by vortex shedding. The system has been demonstrated to show a linear response with water flows in the Reynolds number range 100?3500.     

Semiconductor junction transceiver for fibre optic communication

Measurements on three types of l.e.d.s show that these devices can be used as detectors as well as emitters. Hence these diodes can be used as semiconductor junction transceivers (s.j.t.s) in multiterminal data bus systems.