1、專 業(yè) 英 語 Specialized English Unit 9：第二部分 通信技術 WDM （Wavelength Division Multiplexing）波分復用Specialized English for Communication Engineering Wavelength Division Multiplexing (波分復用):相關背景知識l0數據 話音單波長的系統(tǒng)WDMl0數據 話音l1lnl2 .波分復用系統(tǒng)在一根光纖中同時傳輸多波長光信號的一種技術Optical beams with different wavelengths propagate without

2、affecting one another, so several channels of information (each having a different carrier wavelength) can be transmitted simultaneously over a single fiber. This scheme, called wavelength-division multiplexing (WDM), increases the information-carrying capacity of a fiber.合波器分波器 1 2 3n 1 2 3n波分復用的原理

3、NEW WORDS AND PHRASES visionary n. 幻想家，夢想家significant adj. 重大的，效果顯著的span n. 跨度, 跨距, 范圍 v. 橫越equivalent adj. 相等的, 相當的, 同意義的 n. 等價物, 相等物video n. (adj.) 電視（的），視頻（的），影像（的）approximate adj. 近似的，大概的 adv. ly boost v. 推進，增加，提高eliminate v. 排除，淘汰considerable adj. 相當大的，相當多的simultaneous adj. 同時發(fā)生的，同時存在的，同時的expon

4、ential adj. 指數的，冪的Specialized English for Communication Engineering Specialized English on Communication Engineering Even visionaries such as Albert Einstein and Isaac Newton, who contributed significantly to our understanding of the properties of light and its fundamental importance, would not like

5、ly imagine the communications networks of today. visionary ：空想家, 夢想者, 好幻想的人fundamental ：基礎的, 基本的愛因斯坦和牛頓在我們對光特性的了解及其基本重要性方面做出了重大的貢獻，即使是這樣富于幻想的人也不大可能想象的到今天通信網絡發(fā)展的程度。 Specialized English on Communication Engineering Highways of light span the globe, transmitting massive amounts of information in the tw

6、inkling of an eye. The equivalents of millions of telephone calls are transmitted on a single fiber, thinner than a human hair. Astounding as these advances may seem, we are only at the beginning of what is possible . massive ：大量的；astounding ：令人吃驚的 光的高速公路跨越全球，眨眼之間傳輸巨量的信息。這等于數百萬電話的通信量通過比人的頭發(fā)還細的光纖進行傳輸

7、。這些成就似乎使人很吃驚，但我們只是處于可能會產生更大成就的開始。Specialized English on Communication Engineering The current explosion of traffic in the worldwide networks is ample evidence of the speed with which we are adopting new communications technologies. The growth of wireless systems and the Internet are well-documented

8、phenomena. explosion ：爆發(fā)，激增traffic ：交通, 通行, 運輸, 貿易,交易, (電信)業(yè)務 wireless systems ：無線系統(tǒng)目前全球網絡業(yè)務的激增充分地表明了我們采用新的通信技術的速度。無線系統(tǒng)和因特網的發(fā)展就是很好的證明。Specialized English on Communication Engineering No matter what application it is that is generating traffic, most of this traffic will be carried by the unifying opt

9、ical layer. 不管是哪一種產生業(yè)務的應用，大多數這種業(yè)務將會由統(tǒng)一的光層進行傳送。 Specialized English on Communication Engineering For this reason, the growth of various applications such as telephony (whether cellular or fixed), Internet, video transmission, computer communication and database access leads directly to an increase in

10、 the demand placed on the optical network. telephony ：電話學, 電話, 電話通訊由于這一原因，各種應用的增長，如電話（移動或固定）、因特網、視頻傳輸、計算機通信和數據庫接入直接導致對光網絡持續(xù)增長的需要。 Specialized English on Communication Engineering It is very likely that the optical network will be used to convey large amounts of video information in the future.video

11、information ：視頻信息很有可能將來光網絡會用來傳送大量的視頻信息。Specialized English on Communication Engineering The most striking recent advances in optical networking have taken place in the field of Wavelength Division Multiplexing (WDM). Wavelength Division Multiplexing ：波分復用（WDM）進來光網絡方面最引人注目的進展出現在波分復用(WDM)方面。 Specializ

12、ed English on Communication Engineering These advances have benefited both terrestrial and submarine systems, increased available capacities by several orders of magnitude and correspondingly, reduced costs.terrestrial ：陸地的，地面的submarine ：海底的，水下的這些進展對地面通信系統(tǒng)和海底通信系統(tǒng)都帶來了好處，將可用的容量增加了幾個數量級，而相應地減少了費用。 Spec

13、ialized English on Communication Engineering Until quite recently, it was possible to send only one wavelength, or color, of light along each fiber. A lot of effort has therefore been concentrated in maximizing the amount of information that can be transmitted using a single wavelength. concentrate

14、：集中，匯聚目前，在一根光纖上只能發(fā)送單波長或單顏色的光。因此，大量的努力集中于使用單個波長來傳輸最大量的信息。 Specialized English on Communication Engineering Commercial systems will soon be able to carry 40 Gbit/s on a single wavelength, while in the labs 320 Gbit/s systems have already been demonstrated.Commercial systems ： 商用系統(tǒng)商用系統(tǒng)很快就能夠在單個波長上傳輸40 G

15、bit/s 的信息，而在實驗室，已經演示了傳輸320 Gbit/s 的系統(tǒng)。 Specialized English on Communication Engineering WDM, on the other hand, makes it possible to transmit a large number of wavelengths using the same fiber, effectively sending a “rainbow” of colors, where there was only one color before. rainbow ：彩虹另一方面，WDM使得使用同

16、樣的光纖傳輸很多波長成為可能，可以有效的發(fā)送顏色的“彩虹”，而在以前只有一種顏色。Specialized English on Communication Engineering Already today, commercially available systems can transmit 400 Gbit/s of information on a single fiber. That is equivalent to transmitting approximately 200 feature-length films per second. approximately ：近似地,

17、大約今天商用系統(tǒng)可以在一根光纖上傳輸400 Gbit/s 的信息。這大約等效于每秒傳輸200部故事片。 Specialized English on Communication Engineering Recently, a team of researchers from Bell Labs demonstrated long-distance, error-free transmission of 3.28 Tbit/s over a single optical fiber.error-free：無誤碼的最近，貝爾實驗室的一個研究隊伍展示了在一根光纖上速率高達3.28 Tbit/s 的長

18、途、無誤碼的傳輸系統(tǒng)。 Specialized English on Communication Engineering The major advance that has led to the WDM revolution has been the invention of the Optical Amplifier (OA). Optical Amplifier:光放大器（OA）導致WDM革命的主要進展是光放大器（OA）的發(fā)明。 Specialized English on Communication Engineering Before the invention of the OA,

19、 after having traveled down a fiber for some distance, each individual wavelength had to be converted into the electronic form, then back into optical form and then transmitted into the next span of fiber. 在光放大器（OA）發(fā)明之前，單個波長在經過光纖傳輸一定距離之后，必須轉換成電信號的形式，然后再變換回到光信號形式并通過下一段光纖傳輸。 Specialized English on Com

20、munication Engineering This was relatively expensive, since the optical components involved are highly specialized devices. The OA, however, can boost the signal power of all wavelengths in the fiber, thus eliminating the need for separate regenerators, and allowing many wavelengths to share the sam

21、e fiber.specialized：專用的，專門的boost ：推進，增加，增強，放大regenerator：再生器這樣就使得費用比較昂貴，因為所涉及的光器件是高度專用的器件。然而，光放大器（OA）可以放大光纖中所有波長的信號功率，這樣就不需要不同的再生器并允許許多波長共用同樣的光纖。 Specialized English on Communication Engineering Advances in optical amplifier design have been considerable. First, the operating window has expended fro

22、m 12 nm, in the first generation, to about 80 nm today. This allows the OA to amplify more signals simultaneously. considerable ：重要的，可觀的，相當大的operating window ：工作窗口simultaneously ：同時地光放大器設計方面的進展是相當可觀的。首先，光纖的工作窗口已由第一代的 12 nm擴展到今天的80 nm。這使光放大器可以同時放大更多的信號。Specialized English on Communication Engineering

23、 Second, the development of gain equalization techniques has enabled a much flatter response and allows a number of these amplifiers to be connected in series. There have also been advances in the fibers themselves. gain equalization techniques ：增益均衡技術flatter response ：平坦響應in series ：連續(xù)地, 串聯第二，增益均衡技

24、術的發(fā)展可以產生更平坦的信號響應，并允許這樣的一些放大器以串聯的形式連接。光纖本身也有了進展。Specialized English on Communication Engineering In the early days of optical systems, optical fibers were not built for multi-wavelength transmission. Todays fibers, on the other hand, are designed to have wide transmission windows and are optimized fo

25、r high-capacity, multiple-wave-length transmission.multi-wavelength transmission ：多波長傳輸transmission windows ：傳輸窗口high-capacity ：大容量在早期的光系統(tǒng)中，敷設的光纖不能用于多波長傳輸。另一方面，今天設計的光纖有寬的傳輸窗口，可以優(yōu)化用于大容量、多波長傳輸。 Specialized English on Communication Engineering The growing demand on optical network is a complex issue. O

26、n the one hand, the growth in capacity demand is extraordinary, and this in itself would be a big enough challenge to meet.extraordinary ：非凡的；顯著的對光網絡日益增長的需求是個復雜的問題。一方面，對容量需求的增長非常顯著，這本身就是一個需要面對的很大的挑戰(zhàn)。 Specialized English on Communication Engineering However, this is panied by an increasing variety of

27、 services and applications, as well as much more exacting requirements for quality differentiation. pany ：伴隨然而同時伴隨的是日益增長的各種業(yè)務和應用，以及對不同業(yè)務的更加嚴格的需求。 Specialized English on Communication Engineering For example, there is quite a difference in the quality requirement for a signal being used to transmit a

28、n emergency telephone call or live video converge of a medical operation, as compared with an E-mail that is not urgent and can arrive after several hours.emergency ：緊急情況, 突然事件, 緊急事件urgent ：急迫的, 緊急的例如，用于傳輸緊急電話或者實況醫(yī)療手術轉播的信號，相比于不是很緊急的可以幾個小時后到達的電子郵件來說，信號質量有很大的不同。Specialized English on Communication Eng

29、ineering However, the same optical infrastructure is expected to support this wide variety of services. Internet Protocol (IP) traffic, in particular, is growing exponentially. Internet Protocol (IP) traffic：IP業(yè)務IP：IP業(yè)務traffic：交通, 運輸, 往來; 交通量; 運輸量;交流; 傳達, 傳輸信息;(電信)業(yè)務, 通信量, 通話量然而，人們希望有光網絡結構來支持這種廣泛的業(yè)務

30、。特別是IP業(yè)務，正在以指數形式增長。Specialized English on Communication Engineering In some parts of the world, it is expected that IP will constitute the majority of traffic in the near future. Therefore, existing networks will have to be progressively optimized to handle various types of traffic. progressively ：逐

31、步地optimize ：使最優(yōu)化在世界的一些地方，IP業(yè)務有可能在不久的將來構成業(yè)務中的大部分。因此，現有的網絡必須逐步進行優(yōu)化以處理各種類型的業(yè)務。Specialized English on Communication Engineering WDM has a major advantage in this regard, which is that the different types of traffic can be assigned to different wavelengths, as required. in this regard ：在這點上，在這方面WDM在這方面有很

32、大的優(yōu)勢，就是不同類型的業(yè)務按照需要可以分配不同的波長信號。Specialized English on Communication Engineering A further aspect to consider is access to the optical network. Most users would like to have direct access to the optical network and the enormous capacity it provides. This will take place in stages. access to the optica

33、l network ：接入（訪問）光網絡direct access ：直接接入（訪問）進一步要考慮的是接入光網絡。多數用戶想直接接入到光網絡以利用其所提供的巨大信息的容量。著將會分成幾個階段來完成。Specialized English on Communication Engineering Multi-wave-length optical systems are rapidly spreading out from the core towards the end user. In regional and metropolitan areas, the requirements are

34、 somewhat different from the long-distance area. Multi-wave-length optical systems ：多波長光系統(tǒng)end user ：終端用戶多波長光系統(tǒng)正在快速地從核心網向終端用戶擴展。在局部地區(qū)和城區(qū)的需求與長途通信有些不同。Specialized English on Communication Engineering The dream of Fiber To The Home (FTTH) or desktop is yet to materialize, mainly because of the cost-sens

35、itive nature of this part of the network.Fiber To The Home (FTTH) ：光纖到家（戶）materialize ：實現cost-sensitive ：費用敏感性光纖到家（FTTH）或光纖到桌面的夢想還需要經努力去實現，主要是由于這部分網絡的費用敏感性。Specialized English on Communication Engineering In the near future, residential access may remain copper-based, using technologies such as ADSL

36、 to boost the capacity of traditional copper lines. ADSL ：Asymmetrical Digital Subscriber Loop, 非對稱數字用戶環(huán)線copper-based ：基于銅線的在近來的一些日子里，住戶接入可能還是采用銅線，可以使用ADSL技術以增加傳統(tǒng)銅線的容量。Specialized English on Communication Engineering However, for business offices, optical technology will be used to bring bandwidth t

37、o the end-used. Currently, a lot of Fiber To The Building (FTTB) networks are being developed involving ATM and SDH access equipment at customer premises. Fiber To The Building (FTTB) ：光纖到建筑物ATM ：Asynchronous Transfer Mode 異步傳輸模式SDH ：Synchronous Digital Hierarchy 同步數字系列然而，對于商用辦公室，可采用光纖技術將帶寬送到終端用戶。目前

38、，很多光纖到建筑物網絡正在敷設中，這包括用戶房屋中的ATM和SDH接入設備。Specialized English on Communication Engineering The next step is to use WDM technology for these applications. WDM will first be used in industrial and campus Local Area Network (LAN) environments.Local Area Network (LAN) ：局域網下一步是在這些應用中使用WDM技術。WDM將會首先用于工業(yè)和校園局域網

39、環(huán)境中。Specialized English on Communication Engineering We are at the beginning of a revolution in communications networks, where increasing capacity, variety of applications, and quality of service are placing enormous demands on the optical network. revolution ：革命我們正處于通信網絡革命的開始，越來越大的容量需求，各種各樣的應用以及服務質

40、量正在對光網絡提出巨大的需求。Specialized English on Communication Engineering The revolution of optical network is just beginning, and is advancing vary swiftly towards a future online world in which bandwidth is essentially unlimited, reliable and low-cost.online ：在線式unlimited ：無限的, 無約束的光網絡的革命剛剛開始，正在快速向未來的帶寬無限、可

41、靠和低費用的在線世界發(fā)展。單信道全光中繼數字通信光-電-光中繼的數字通信典型通信鏈路方框圖Site ASite BPost OAPost OALine OAPre OAMUXDeMUX T1 T2 Tn-1 Tn R1 R2 Rn-1 Rn 波分復用器光發(fā)送器光接收器光 纜12n-1n 1, 2, nA 端B 端解復用器多路光波復用單纖傳輸復 習詞匯光纖通信 optical fiber communication光源 light source傳輸介質 transmission medium波長 wavelength激光器 laser色散 dispersion帶寬 bandwidth單模光纖 s

42、ingle-mode fiber復 習詞匯多模光纖 multi-mode fiber長途干線 long-haul trunk商用技術 commercial technology寬帶用戶 wideband subscriber光檢測器 photodetector門限電流 threshold current纖維光網絡 fiber-optic networks視頻帶寬 video bandwith復 習詞匯光纖通信系統(tǒng) fiber-optic communication system電磁波譜 electromagnetic spectrum電磁載波 electromagnetic carrier w

43、ave自由空間光通信 free-space optical communication寬帶綜合業(yè)務數字網 broadband integrate-services digital network (BISDN)復 習詞匯repeater spacing 中繼距離commercial technology 商用技術optical fiber communication 光纖通信long-haul munication system 長途通信系統(tǒng)the low-loss silica fiber 低損耗石英光纖propagation mode 傳播模式refractive index profil

44、e 折射率分布圖optical receiver 光接收機dielectric 電介質，絕緣材料復 習詞匯destructive interference 相消干擾（干涉）stepped-index fiber 階躍（折射率）光guided lightwave systems 引導型光波系統(tǒng)unguided optical systems 非引導型光波系統(tǒng)intersatellite communication 衛(wèi)星間通信long-haul munication 長途通信short-haul munications 短途通信central processing unit (CPU) 中央處理器

45、local area network (LAN) 局域網復 習詞匯wide area network (WAN) 廣域網network topology 網絡拓撲token ring network 令牌環(huán)網Wavelength Division Multiplexing (WDM) 波分復用Optical Amplifier (OA) 光放大器Fiber To The Home (FTTH) 光纖到戶Fiber To The Building (FTTB) 光纖到大樓小 結被動語態(tài)及其譯法譯成漢語被動句譯成漢語的主動句譯成漢語的加強語句譯成漢語無主句WDM Specialized Engli

46、sh on Communication Engineering Fortunately, we will soon be in a position to route individual wavelengths flexibly through an optical network. Features such as add/drop and cross-connection in the optical domain are being made possible by advance in photonics. add/drop ：上下、分插cross-connection ：交叉連接photonics ：光子學幸運的是，我們很快就可以通過光網絡靈活的傳送單個波長的信號。在光子學方面的發(fā)展使得在光域上具有信號上下和交叉連接的特性正在成為可能。Specialized English on Communication Engineering I would like to draw attention to a few recent advances in this area. Firstly, the so-called digital wrapper is in the process of being sta