電子類(lèi)專(zhuān)業(yè)英語(yǔ)電子教案第十四課

1、 學(xué)習(xí)重點(diǎn)學(xué)習(xí)重點(diǎn)： （1 1）掌握有關(guān)光通信的基本單詞、詞組和縮略語(yǔ)掌握有關(guān)光通信的基本單詞、詞組和縮略語(yǔ)的基本含義及用法的基本含義及用法 （2 2）培養(yǎng)閱讀翻譯有關(guān)光通信的科技文獻(xiàn)和產(chǎn)品培養(yǎng)閱讀翻譯有關(guān)光通信的科技文獻(xiàn)和產(chǎn)品說(shuō)明書(shū)的能力說(shuō)明書(shū)的能力 （3 3）學(xué)習(xí)如何撰寫(xiě)科技論文英文摘要并初步掌握）學(xué)習(xí)如何撰寫(xiě)科技論文英文摘要并初步掌握在內(nèi)容、句法、時(shí)態(tài)、語(yǔ)態(tài)等方面的特點(diǎn)在內(nèi)容、句法、時(shí)態(tài)、語(yǔ)態(tài)等方面的特點(diǎn) coaxial kuksl a 同軸的同軸的 distortion dist:n n. 扭曲；崎變扭曲；崎變 dispersion disp:n n. 散布散布, 分散分散 drawb

2、ack dr:.bk n. 不利點(diǎn)不利點(diǎn) eliminate ilimineit v. 除去；排除；消除除去；排除；消除 incoherent .inkuhirnt a. 不相干的不相干的 interference .intfirns n.干涉干涉 index indeks n. 索引；指針；指數(shù)索引；指針；指數(shù) modal mudl a. 模態(tài)的模態(tài)的 refractive rifrktiv a. 折射的折射的 silica silik n. 矽土；二氧化硅矽土；二氧化硅 sophisticate sfistikeit v. 摻合；弄復(fù)雜摻合；弄復(fù)雜 spectrum spektrm n.

3、光譜光譜 stray strei a. 雜散的雜散的 n. pl.雜散電容；天電干擾雜散電容；天電干擾2. 2. 課文翻譯講解課文翻譯講解 fibre-based systems have largely replaced radio transmit systems for long-haul data transmission, and largely used for telephony, internet traffic, long high-speed local area networks (lans), cable-tv, and increasingly also used f

4、or shorter distances. in most cases, silica fibers are used, except for very short distances, where plastic optical fibres can be advantageous. 翻譯：翻譯：基于光纖的系統(tǒng)已基于光纖的系統(tǒng)已大部分取代了無(wú)線電傳輸系統(tǒng)長(zhǎng)距離傳輸數(shù)據(jù)，并主要用于取代了無(wú)線電傳輸系統(tǒng)長(zhǎng)距離傳輸數(shù)據(jù)，并主要用于電話(huà)、互聯(lián)網(wǎng)通信、長(zhǎng)距離高速局域網(wǎng)（電話(huà)、互聯(lián)網(wǎng)通信、長(zhǎng)距離高速局域網(wǎng)（ lan ）、有線電視，并且現(xiàn)在已越來(lái)越多）、有線電視，并且現(xiàn)在已越來(lái)越多地用于短距離通信。除了非

5、常短距離的通信之外，大多情況下用二氧化硅光纖，在短地用于短距離通信。除了非常短距離的通信之外，大多情況下用二氧化硅光纖，在短距離通信中使用塑膠光纖是有利的。距離通信中使用塑膠光纖是有利的。 compared with the systems based on electrical cables, there are a number of compelling advantages, which lead to the widespread adoption of fibre optic cable for telecommunications, the most important are:

6、 (1) much lower levels of signal attenuation, 0.2 db/km for modern single-mode silica fibers, so that many tens of kilometers can be bridged without amplifying the signals. 翻譯：翻譯：與電纜系統(tǒng)相比，光纖電纜具有一些極據(jù)竟?fàn)幮缘膬?yōu)點(diǎn)，這使得它被廣泛與電纜系統(tǒng)相比，光纖電纜具有一些極據(jù)竟?fàn)幮缘膬?yōu)點(diǎn)，這使得它被廣泛應(yīng)用于通信系統(tǒng)，這些優(yōu)點(diǎn)最重要的是：應(yīng)用于通信系統(tǒng)，這些優(yōu)點(diǎn)最重要的是：（1）低得多的衰減，現(xiàn)代的單模二氧化硅光纖

7、信號(hào)衰減約為）低得多的衰減，現(xiàn)代的單模二氧化硅光纖信號(hào)衰減約為0.2 db/km，這樣，這樣，無(wú)需放大信號(hào)就可跨越數(shù)萬(wàn)公里。無(wú)需放大信號(hào)就可跨越數(shù)萬(wàn)公里。 (2) fibre optic cabling provides a much higher bandwidth allowing more data to be delivered. for example, the wavelength range from 1.3 m to 1.6 m corresponds to a bandwidth as large as 43 thz, which are some orders of mag

8、nitude higher than that of any electrical cable. even so, the theoretical potential of this bandwidth has not been fully utilized so far. (3) fibre optic cables are much lighter than the coaxial cables, so that the cost of laying a fiber-optic cable is much lower than the coaxial cables. 翻譯：翻譯：2）光纜可

9、提供高得多的帶寬，從而傳遞更多的數(shù)據(jù)。舉例來(lái)說(shuō)，波長(zhǎng)范圍）光纜可提供高得多的帶寬，從而傳遞更多的數(shù)據(jù)。舉例來(lái)說(shuō)，波長(zhǎng)范圍從從1.3 m至至1.6 m所對(duì)應(yīng)的帶寬是所對(duì)應(yīng)的帶寬是43thz，比普通電纜高出了幾個(gè)數(shù)量級(jí)。即，比普通電纜高出了幾個(gè)數(shù)量級(jí)。即便如此，從理論講，此帶寬的潛力至今仍未被充分利用。便如此，從理論講，此帶寬的潛力至今仍未被充分利用。（3）光纖電纜遠(yuǎn)輕于同軸電纜，這就使得鋪設(shè)光纖電纜的成本遠(yuǎn)低于同軸電纜。）光纖電纜遠(yuǎn)輕于同軸電纜，這就使得鋪設(shè)光纖電纜的成本遠(yuǎn)低于同軸電纜。 (4) fibre optics does not suffer from stray interferen

10、ce, such as ground loops or electromagnetic interference that often occurs with coaxial cabling. just for reasons of these advantages, optical data transmission is increasingly used in various areas today, such as for example telephony, internet traffic, and cable tv, mostly for longer transmission

11、distances of at least a few kilometers. there is, however, a tendency for optical systems to penetrate areas with smaller and smaller transmission distances. 翻譯：翻譯：4）光導(dǎo)纖維不會(huì)遭受雜散干擾，而諸如接地環(huán)路或電磁干擾之類(lèi)的雜散干）光導(dǎo)纖維不會(huì)遭受雜散干擾，而諸如接地環(huán)路或電磁干擾之類(lèi)的雜散干擾卻在使用同軸電纜時(shí)常常發(fā)生。擾卻在使用同軸電纜時(shí)常常發(fā)生。 正是由于具有這些優(yōu)勢(shì)，光數(shù)據(jù)傳輸在今天被越來(lái)越多地應(yīng)用在各個(gè)領(lǐng)域，如正是由于具有

12、這些優(yōu)勢(shì)，光數(shù)據(jù)傳輸在今天被越來(lái)越多地應(yīng)用在各個(gè)領(lǐng)域，如電話(huà)、互聯(lián)網(wǎng)通訊、有線電視等，這些多數(shù)用于至少有幾公里的較長(zhǎng)傳輸距離。然電話(huà)、互聯(lián)網(wǎng)通訊、有線電視等，這些多數(shù)用于至少有幾公里的較長(zhǎng)傳輸距離。然而，目前有將光系統(tǒng)以越來(lái)越小的傳遞距離滲透到各個(gè)領(lǐng)域的趨勢(shì)。而，目前有將光系統(tǒng)以越來(lái)越小的傳遞距離滲透到各個(gè)領(lǐng)域的趨勢(shì)。 current local area networks (lans) work well with electrical cables for data rates of 100 mbit/s, but electrical cables do not serve that w

13、ell at rates of e.g. 10 gbit/s, so that optical connections will become important. supercomputers may soon extensively use optical interconnects for rather short distances. optical board-to-board connections, optical chip-to-chip and even intra-chip connections are seriously considered, partly alrea

14、dy developed. 翻譯：翻譯：目前，使用電纜的局域網(wǎng)很好地工作于目前，使用電纜的局域網(wǎng)很好地工作于100 mbit/s數(shù)據(jù)速率，但在數(shù)據(jù)率數(shù)據(jù)速率，但在數(shù)據(jù)率達(dá)到如達(dá)到如10 gbit/s時(shí)電纜的服務(wù)不是很好，所以光纖系統(tǒng)將變得很重要。超級(jí)計(jì)時(shí)電纜的服務(wù)不是很好，所以光纖系統(tǒng)將變得很重要。超級(jí)計(jì)算機(jī)可能很快會(huì)在相當(dāng)短的距離內(nèi)使用光纖連接。光的板對(duì)板連接，光的片對(duì)片算機(jī)可能很快會(huì)在相當(dāng)短的距離內(nèi)使用光纖連接。光的板對(duì)板連接，光的片對(duì)片連接，甚至內(nèi)部芯片連接都在認(rèn)真考慮，部分已進(jìn)行了開(kāi)發(fā)。連接，甚至內(nèi)部芯片連接都在認(rèn)真考慮，部分已進(jìn)行了開(kāi)發(fā)。 however, fiber systems

15、 are somewhat more sophisticated to install and operate, so that they tend to be less economical if their full transmission capacity is not required. therefore, usually the connection to the homes and offices are still bridged with electrical cables, while fiber-based communications do the bulk of t

16、he long-haul transmission. any fibre optic data transmission system is comprised by a number of different elements, mainly are: transmitter (light source), fibre optic cable, optical repeater and amplifier, receiver (detector).翻譯：翻譯：不過(guò)，光纖系統(tǒng)的安裝和操作有點(diǎn)復(fù)雜，以至于如果不充分利用它們的全部不過(guò)，光纖系統(tǒng)的安裝和操作有點(diǎn)復(fù)雜，以至于如果不充分利用它們的全部傳

17、輸容量，使用它們往往就不太經(jīng)濟(jì)。因此，家里和辦公室的連接線通常還是使用傳輸容量，使用它們往往就不太經(jīng)濟(jì)。因此，家里和辦公室的連接線通常還是使用電纜，而基于光纖的通信大部分用于遠(yuǎn)距離傳輸。電纜，而基于光纖的通信大部分用于遠(yuǎn)距離傳輸。 任何光纖數(shù)據(jù)傳輸系統(tǒng)都由一些不同的部分組成，主要是：發(fā)射機(jī)（光源），任何光纖數(shù)據(jù)傳輸系統(tǒng)都由一些不同的部分組成，主要是：發(fā)射機(jī)（光源），光纖光纜，光中繼器和放大器，接收器（探測(cè)器）。光纖光纜，光中繼器和放大器，接收器（探測(cè)器）。 originally, large lasers have been used for optical fibre telecommuni

18、cation systems. today, however, a variety of semiconductor devices can be used. the most commonly used devices are light emitting diodes (leds), and other semiconductor laser diodes. the simplest transmitter device is the led, main advantage of which is cheap, and this makes it ideal for low cost ap

19、plications where only short runs are needed. 翻譯：翻譯： 最初，大型激光器用于光纖電信系統(tǒng)。但是現(xiàn)在可以使用各種各樣的半導(dǎo)體最初，大型激光器用于光纖電信系統(tǒng)。但是現(xiàn)在可以使用各種各樣的半導(dǎo)體設(shè)備。最常用的器件是發(fā)光二極管（設(shè)備。最常用的器件是發(fā)光二極管（ led ），以及其它半導(dǎo)體激光二極管。最簡(jiǎn)單），以及其它半導(dǎo)體激光二極管。最簡(jiǎn)單的發(fā)射裝置是的發(fā)射裝置是led。它的主要優(yōu)點(diǎn)在于價(jià)格便宜，因而，它成為低成本短距離應(yīng)用的。它的主要優(yōu)點(diǎn)在于價(jià)格便宜，因而，它成為低成本短距離應(yīng)用的理想選擇。理想選擇。 however they have a numbe

20、r of drawbacks. the first is that they offer a very low level of efficiency. only about 1% of the input power enters the optical fibre. the other disadvantage of leds is that they produce incoherent light that covers a relatively wide spectrum, typically between 30 and 60 nm. this means that any chr

21、omatic dispersion in the fibre will limit the bandwidth of the system. in view of their performance, leds are used mainly in local-area-network applications where the data rates are typically in the range 10-100 mb/s and transmission distances are a few kilometres. 翻譯：翻譯：不過(guò)，它們也有一些弊端：第一個(gè)問(wèn)題是它們所不過(guò)，它們也有

22、一些弊端：第一個(gè)問(wèn)題是它們所提供的工作效率非常低，只有工作效率非常低，只有約約10 的輸入功率進(jìn)入光纖；的輸入功率進(jìn)入光纖；led的另一個(gè)缺點(diǎn)是，他們所生產(chǎn)的非相干光覆蓋比的另一個(gè)缺點(diǎn)是，他們所生產(chǎn)的非相干光覆蓋比較寬的頻譜，通常是較寬的頻譜，通常是30到到60納米，這意味著在光纖中任何納米，這意味著在光纖中任何顏色的色散都將限制系統(tǒng)的色散都將限制系統(tǒng)的帶寬。鑒于它們的性能，目前發(fā)光二極管主要用于局域網(wǎng)，這些地方數(shù)據(jù)傳輸率通常帶寬。鑒于它們的性能，目前發(fā)光二極管主要用于局域網(wǎng)，這些地方數(shù)據(jù)傳輸率通常在在10-100 mb/s，并且傳輸距離為幾公里遠(yuǎn)。，并且傳輸距離為幾公里遠(yuǎn)。 then las

23、ers are used, although more costly, they offer some significant advantages. the first instance is that they are able to provide a much higher level of efficiency in the transfer of the light into the fibre optic cable. typically the coupling efficiency into a single mode fibre may be as high as 50%.

24、 a further advantage is that lasers have a very narrow spectral bandwidth, which enables the lasers to transmit data at much higher rates because modal dispersion is less apparent. 翻譯：翻譯：然后使用激光，雖然較昂貴，他們卻有著顯著的優(yōu)勢(shì)。首先，在把光信號(hào)然后使用激光，雖然較昂貴，他們卻有著顯著的優(yōu)勢(shì)。首先，在把光信號(hào)轉(zhuǎn)換進(jìn)入光纖電纜時(shí)，他們具有高得多的效率，耦合成為一個(gè)單模光纖的通常效轉(zhuǎn)換進(jìn)入光纖電纜時(shí)，他們具有

25、高得多的效率，耦合成為一個(gè)單模光纖的通常效率可能高達(dá)率可能高達(dá)50 。更進(jìn)一步的好處是激光有一個(gè)很窄的譜帶寬度，它使激光以高。更進(jìn)一步的好處是激光有一個(gè)很窄的譜帶寬度，它使激光以高得多的速率傳送數(shù)據(jù)，因?yàn)槟Ｊ降纳⒉皇悄敲疵黠@。得多的速率傳送數(shù)據(jù)，因?yàn)槟Ｊ降纳⒉皇悄敲疵黠@。 another advantage is that semiconductor lasers can be modulated directly at high frequencies because of short recombination time for the carriers within the semi

26、conductor material. because the laser diodes are often directly modulated, this provides a very simple and effective method of transferring the data onto the optical signal, achieved by controlling current applied directly to the device. this in turn varies the light output from the laser. 翻譯：翻譯：另一個(gè)

27、好處是半導(dǎo)體激光器可在高頻率直接調(diào)制，由于在半導(dǎo)體材料中載另一個(gè)好處是半導(dǎo)體激光器可在高頻率直接調(diào)制，由于在半導(dǎo)體材料中載流子的復(fù)合時(shí)間很短。因?yàn)榧す舛O管往往直接進(jìn)行調(diào)制，這就提供了將數(shù)據(jù)轉(zhuǎn)流子的復(fù)合時(shí)間很短。因?yàn)榧す舛O管往往直接進(jìn)行調(diào)制，這就提供了將數(shù)據(jù)轉(zhuǎn)換成光信號(hào)一個(gè)非常簡(jiǎn)單而有效的方法，這一轉(zhuǎn)換是用控制直接加到激光設(shè)備上換成光信號(hào)一個(gè)非常簡(jiǎn)單而有效的方法，這一轉(zhuǎn)換是用控制直接加到激光設(shè)備上的電流來(lái)達(dá)到的。這反過(guò)來(lái)又改變了由激光器輸出的光信號(hào)。的電流來(lái)達(dá)到的。這反過(guò)來(lái)又改變了由激光器輸出的光信號(hào)。 however for very high data rates or very lon

28、g distance links, it is more effective to run the laser at a constant output level (continuous wave). the light is then modulated using an external device, the advantage of which is that it increases the maximum link distance because an effect known as laser chirp is eliminated. this chirp broadens

29、the spectrum of the light signal and this increases the chromatic dispersion in the fibre optic cable. 翻譯：翻譯：但是對(duì)于非常高的數(shù)據(jù)傳輸速率或非常長(zhǎng)距離的鏈接，以恒定的輸出（連續(xù)但是對(duì)于非常高的數(shù)據(jù)傳輸速率或非常長(zhǎng)距離的鏈接，以恒定的輸出（連續(xù)波）運(yùn)行激光更為有效。用外部設(shè)備進(jìn)行光調(diào)制，其優(yōu)點(diǎn)是增加了最大鏈路距離，波）運(yùn)行激光更為有效。用外部設(shè)備進(jìn)行光調(diào)制，其優(yōu)點(diǎn)是增加了最大鏈路距離，因?yàn)橐环N被稱(chēng)為激光啾聲的現(xiàn)象被消除了。這種激光啾聲拓寬了光信號(hào)的頻譜，增因?yàn)橐环N被稱(chēng)為激光啾聲的現(xiàn)象被消除

30、了。這種激光啾聲拓寬了光信號(hào)的頻譜，增加了光纖電纜中的色散。加了光纖電纜中的色散。 a fibre optic cable consists of a core, a cladding, and a protective coating outside of the cladding, as schematically shown in figure 14-1. the cladding is a layer around the core and the refractive index of which is slightly lower than that of the core. th

31、is means that the light passing down the core undergoes total internal reflection when it reaches the core / cladding boundary, and it is thereby contained within the core of the optical fibre.翻譯：翻譯：光纜由纜芯、包層以及外部有覆層的保護(hù)涂層組成，此保護(hù)涂層是在包層的外光纜由纜芯、包層以及外部有覆層的保護(hù)涂層組成，此保護(hù)涂層是在包層的外面，如圖面，如圖14-1所示。包層是在纜芯的周?chē)移湔凵渎氏鄬?duì)纜芯

32、的要低。這意味著當(dāng)在所示。包層是在纜芯的周?chē)移湔凵渎氏鄬?duì)纜芯的要低。這意味著當(dāng)在纜芯中進(jìn)行傳輸?shù)墓獾竭_(dá)核心纜芯中進(jìn)行傳輸?shù)墓獾竭_(dá)核心/包層邊界時(shí)要進(jìn)行全內(nèi)反射，因而光被包圍在纜芯中。包層邊界時(shí)要進(jìn)行全內(nèi)反射，因而光被包圍在纜芯中。 repeaters and amplifiers must be used in order to overcome the attenuation and the distortion of the light signal along the cable as the signals transmitted over longer distances. the

33、 heart of the receiver is a photo-detector, which normally is a semiconductor device and may be a p-n junction, a p-i-n photo-diode or an avalanche photo-diode. 翻譯：翻譯：隨著信號(hào)傳輸距離加長(zhǎng)，必須使用中繼器和放大器，以克服光信號(hào)沿電纜傳隨著信號(hào)傳輸距離加長(zhǎng)，必須使用中繼器和放大器，以克服光信號(hào)沿電纜傳輸時(shí)產(chǎn)生的衰減和失真。輸時(shí)產(chǎn)生的衰減和失真。 接收器心臟是一個(gè)光電探測(cè)器，它通常是半導(dǎo)體器件，也可能是一個(gè)接收器心臟是一個(gè)光電探測(cè)器，

34、它通常是半導(dǎo)體器件，也可能是一個(gè)pn結(jié)，一結(jié)，一個(gè)個(gè)pin光電二極管或雪崩光電二極管。光電二極管或雪崩光電二極管。 phototransistors are not used because they do not have sufficient speed. once the optical signal from the fibre optic cable has been applied to the photo-detector and converted into an electrical format, it can be processed to recover the dat

35、a, which then can be passed to its final destination. 翻譯：翻譯：沒(méi)有使用光電晶體管是因?yàn)樗鼈兯俣炔粔?。一旦光纖電纜中光信號(hào)傳遞給光沒(méi)有使用光電晶體管是因?yàn)樗鼈兯俣炔粔?。一旦光纖電纜中光信號(hào)傳遞給光電探測(cè)器并轉(zhuǎn)換成電氣格式，它就可被加工處理以恢復(fù)原始數(shù)據(jù)，然后傳給最終目電探測(cè)器并轉(zhuǎn)換成電氣格式，它就可被加工處理以恢復(fù)原始數(shù)據(jù)，然后傳給最終目的地。的地。3.3.疑難解析疑難解析 1) in most cases, silica fibers are used, except for very short distances, where pl

36、astic optical fibers can be advantageous. 除了短距離通信之除了短距離通信之外，大多情況下用二氧化硅光纖，短距離通信外，大多情況下用二氧化硅光纖，短距離通信使用塑膠光纖是有利的。使用塑膠光纖是有利的。in most cases 意為意為“在大多數(shù)情況下在大多數(shù)情況下”，這里，這里case意為意為 “狀況、狀況、情形、場(chǎng)合情形、場(chǎng)合”。 比較：比較：in that case意為意為“如果那樣的話(huà)如果那樣的話(huà)”；in ones case意為意為“就就的情況而言的情況而言”；in any case意為意為“無(wú)論如何、不管怎樣無(wú)論如何、不管怎樣”。 2) compared with the systems based on electrical cables, there are a number of compelling advantages which lead to the widespread adoption of