通信与电子信息专业英语 课件 Unit 9 Optical Communication.pptx

Unit9OpticalCommunication

9.1OpticalCommunicationSystems

9.2PassiveOpticalNetworks

9.1OpticalCommunicationSystemsWordsandExpressionsBackgroundsText

WordsandExpressionswaveguide n.波导aclassofdevicesthatconfinesanddirectsthepropagationofelectromagneticwaves.typicalexamplesincludehollowmetallictubes,coaxialcables,andopticalfibres.

WordsandExpressions5accommodate v.容纳；为…提供空间； 顺应，适应（新情况）Becausethefrequencyoflightisextremelyhigh,itcanaccommodateveryhighratesofdatatransmissionwithexcellentreliability.由于光的频率非常高，因此光通信可以提供非常高的数据传输速率，并具有出色的可靠性。

WordsandExpressions6photodetector n.光电探测器；光检测器photodiode 光电二极管phototransistor 光电三极管Photodiodesaredesignedtodetectphotonsandcanbeusedincircuitstosenselight.Phototransistorsarephotodiodeswithsomeinternalamplification.

WordsandExpressions7LASER:LightAmplificationbyStimulatedEmissionofRadiation n.激光；激光器laserprinter 激光打印机monochromatic adj.单色的；单色光的； 单频的；单能的polychromatic 多色的monochromaticsource 单色光源

WordsandExpressions8coherent adj.相干的；连贯的； 一致的；合乎逻辑的incoherent 非相干的，不连贯的coherentopticalcommunication 相干光通信insync(synchronization) 同步；一致；协调intensitymodulation 强度调制

WordsandExpressions9NRZ:Non-ReturntoZero 不归零的；不归零制OOK:On-OffKeying 开关键控；通断键控DigitalmodulationisusuallyNRZ-formattedbinarydatathatturnsalaserofforontoproduceoff-onkeying(OOK)oramplitude-shiftkeying(ASK).

WordsandExpressions10attenuation n.衰减；变薄；稀释echoattenuation 回声衰减attenuationcoefficient(dB/km) 衰减系数Communicationbylightbeaminfreespaceisimpracticaloververylongdistancesbecauseofthegreatattenuationofthelightduetoatmosphericeffects.在自由空间中通过光束进行长距离通信是不切实际的，因为大气效应会导致光的大幅衰减。

WordsandExpressions11reflect v.反射(声、光、热等)；反映；认真思考refract v.使(光线)折射；使产生折射disperse v.散射；分散；驱散；疏散；传播

WordsandExpressions12obliterate v.毁掉；覆盖；清除Artificiallightbeamsused