科技论文.docx

科技论文.docx

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科技论文

科技论文

题目Opticalfibercommunicationtechnology,historyandstatusofdevelopment

系别尚德光伏学院

专业应用电子技术（光电子技术方向）

班级0901

学生姓名彭博

学号090281

指导教师朱芳

2012年4月

Opticalfibercommunicationtechnology,historyandstatusofdevelopment

Abstract：

Opticalfibercommunicationlinewiththehigh-speed,largecapacity,highsecurity,etc.,butthepracticalapplicationofopticalfibercommunicationscantransmitinformationinthehumanisnoteasy,theirdevelopmenthasexperiencedmanytechnicaldifficultiestosolvethesetechnicalproblems,opticalfibercommunicationscanbefurtherdevelopment.

Thisarticlefromthelightsourceandtransmissionmedium,optoelectronicdevices,opticalfibercommunicationsystemstodemonstratethedevelopmentofopticalcommunicationtechnology.

KeyWords：

OpticalfibercableopticalfibercommunicationtechnologyactivedevicesPassiveComponentsFiberCommunicationSystem

【Body】

Theinherentadvantagesoflightitisdestinedtoserveashumanhistory,therolecannotbeignored,withthedevelopmentofhumantechnology,itsapplicationmorewidely;theadvantagesarebecomingmoreprominent.

Opticalfibercommunicationistosendtheimage,anddatatotheopticalcarriersignalmodulationtoopticalfiberasthetransmissionmediumofcommunication.Asacarrierwavefrequencyismuchhigherthantheradiofrequencyasthetransmissionmediumoffthancoaxialcableorfiber-opticwaveguidelossismuchlower,sorelativetocablecommunicationsormicrowavecommunications,opticalfibercommunicationhasmanyuniqueadvantages.

Highlighttheadvantagesofrealapplicationsofopticalfibercommunicationstohumanlife,andmanytechnologies,requiresaprocessofdevelopment.

First,theformationofopticalfibercommunicationtechnology

（A）,theearlyopticalcommunications

Lighteverywhere,thissentenceisnoexaggeration.Earlyinhumandevelopment,humanbeingshavebeguntouselighttotransmitinformation,andtherearemanysuchexamples.

Gesturesareaformofvisualcommunication,cannotbeinthedark.Thetransmissionsystemduringthedayandthesunaslightsource,solarradiationcarrythesender'sinformationtransmittedtotherecipient,handmovementsmodulatedlight,thehumaneyeasdetector.

Inaddition,thereisabeacon3000yearsagountilnowstillusethelights,semaphoreandsocanberegardedasprimitiveformsofopticalcommunications.Theemergenceofthetelescopeandgreatlyextendthelightofthesevisualformsofcommunicationdistance.

Suchopticalcommunicationhasasignificantdisadvantageisthattheycantransportcapacityisextremelylimited.

Modernhistory,asearlyas1880,theUnitedStatesBell（Bell）inventedthe"opticaltelephone."Thislighttelephoneuseofsunlightorarclampaslightsource,thebeamisfocusedthroughalensinfrontofthevibrationtransmitterlens,sothatthelightintensitychangeswiththevoice,toachievelightintensitymodulatedvoice.Atthereceivingend,withtheparabolicreflectorcameintothebeamreflectedfromtheatmosphereintothesiliconphoto-pool,sothatthelightsignalistransformedintothecurrenttransmittedtothereceiver.

Lightphoneandnotgetinthelivesofactualuse,mainlybecausetherewasnosuitablelightsourceandtransmissionmedium.Theiruseofnaturallightfornon-coherentlight,directionalwell,noteasytomodulationandtransmission;theairastransmissionmedium,thelosswillbegreat,cannotachievelong-distancetransmission,butalsovulnerabletoweather,trafficandextremelyunstableandreliable.

Itseemsthatthislightthephoneandnotmuchpracticalvalue,however,wehavetosay,lightphoneisstillagreatinvention,itsappearanceasthecarrierprovedthattransmitinformationusinglightwavesispossible,therefore,toBellTelephoneasmodernopticalcommunicationopticalprototypewithouttoomuch.

（B）,Theformationofmodernopticalfibercommunicationtechnology

Withthedevelopmentofsociety,increasingtheamountofinformationtransmissionandexchange,thetraditionalmeansofcommunicationcannotmeetpeople'sneeds.Inordertoexpandthecommunicationcapacity,communicationfromwaveandshortwavedevelopedtomicrowave,millimeterwave,whichisinfactthecarrierfrequencybyincreasingcommunicationthroughcommunicationcapacitytoexpand.

Continuetoimprovethefrequencybandtolight,lightisthemostfamiliarofelectromagneticwaves,thewavelengthatthemicronlevel,andthefrequencyofmagnitudecomparedtoHz,whichhigherthanthecommonlyusedmicrowavefrequency~times.Inviewofthis,usinglightasthecarrierforcommunication,communicationcapacitywillgreatlyexceedthetraditionalmeansofcommunication.

Tothedevelopmentofopticalcommunications,themostimportantissueistofindalightsourceforopticalcommunicationsandtransmissionmedia.

In1970,fiberopticsandlaserresearchatthesametimethetwocomeoutopenedthecurtainofopticalfibercommunication,sowecalledtheOpticalFiberCommunication1970,the"YearOne."

1,lightsource

In1960,theUnitedStates,Mailman（Thiamin）inventedtherubylaser,whichcanproducecoherentmonochromaticlightthatlightmodulationofhigh-speedinformationaspossible.

Andcomparedtoordinarylight,laserwithnarrowspectralwidth,directionexcellent,highbrightness,andthefrequencyandphasecharacteristicsofamoreconsistentsound.Laserisahighlycoherentlight,itscharacteristicsandradiowavesimilartoanidealopticalcarrier.

However,therubylaserbeamemittedisnoteasytotransfercoupledintothefiber,thecouplingefficiencyisverylow,sotheneedtodevelopminiaturizedlaserlightsources.

In1970,theUnitedStates,BellLabs,NECCorporation（NEC）andtheformerSovietUnionhasbrokenthroughthesemiconductorlaseratlowtemperature（-200）orunderpulsedexcitationconditionsofworkrestrictions,thesuccessfuldevelopmentofroomtemperaturecontinuousoperationofthegalliumaluminumarsenide（Galas）double-heterostructuresemiconductorlaser（shortwavelength）.Althoughthelifespanofonlyafewhours,butitsmeaningissignificant,itisthedevelopmentofsemiconductorlaserbasis.In1973,thesemiconductorlaserlifeupto100,000hours（about11.4years）,theextrapolatedlifeof100millionhours,fullymeetthepracticalrequirements.Duringthisperiod,1976NTTdevelopedemissionwavelengthof1.3ofindiumgalliumarsenidephosphorus（IngaAsp）laser,in1979theUnitedStatesTelegraphandTelephone（AT&T）Company,andNTTdevelopedtheemissionwavelengthof155consecutiveoscillationsemiconductorlasers.

Theinventionandapplicationoflaserstomakesleepinga80-yearopticalcommunicationsintoanewstage.

2,thetransmissionmedium

1）Atmospheric

1961to1970,peoplemainlyuseofatmospherictransportofopticalsignals.MassachusettsInstituteofTechnologyuseHe-Nelasersandlasersforatmosphericlasercommunication.Testprovedthatcarryinformationusinglightwavesspreadthroughtheatmospheretoachievepointtopointcommunicationispossible,buttherearemanyatmosphericopticalcommunicationtransmissionseriousproblems:

（1）Communicationcapacityandqualityveryseriouslyaffectedbyclimate.Asrain,fog,snowandatmosphericdustabsorptionandscattering,lightattenuationgreat.Forexample,raincancause30dB/kmattenuation,fogattenuationupto120dB/km.

（2）Thedensityandtemperatureoftheatmosphereisveryuneven,resultinginchangesintherefractiveindex,coupledwiththeimpactofatmosphericturbulence,beampositionshiftmayoccur,andjitter.Thusthedistanceandstabilityofcommunicationareseverelylimited,cannotbeachieved"allweather"communication.

（3）Atmospherictransmissionequipmentlocatedataheightrequirement,thesendingandreceivingdevicesmustbeastraightlinevisible.Thegeographicalconditionsmaketheapplicationofatmospherictransportcommunicationhasgreatlimitations.

Althoughsolid-statelasers（forexample,neodymium-dopedyttriumaluminumgarnet（Nd:

YAG）laser）oftheinventionenhancedthelaunchopticalpower,toextendthetransmissiondistance,sothatopticalcommunicationcancrossrivers,islands,andsomespecificoccasionsbetweenuse,buttheatmosphericstabilityandreliabilityoflasercommunicationisstillnotresolved.

Inordertoovercometheimpactofclimateonlasercommunication,peoplenaturallythinkofthelaserbeamislimitedtoaparticularspacetransmission.Haveproposedawaveguidelensandmirrorlightwaveguidetransmissionsystem.Lenswaveguideisametaltubeatregularintervalsfromtheinstallationofalens,eachlensthebeamtransmittedthroughthenextlensconvergenceachieved.Mirrorwaveguideandwaveguidetransmissionsimilartothatusedwiththebeampropagationdirectionattheangleoftwoparallelmirrorsinsteadoflensesandcomposition.

Thetwowaveguidesistheoreticallyfeasible,butinpracticalapplicationsencounteredinsurmountabledifficulties.Firstofall,on-sitecalibrationandinstallationofconstructionisverycomplicated;secondly,inordertopreventtheimpactofgroundmovementsonthewaveguide,thewaveguidemustbeburiedorselectvehiclesscarceregions.

Intheabsenceoffindingreliableandlow-losstransmissionmedium,opticalcommunication,oncetheresearchintothedownturn.

2）Fiber

Todeveloptheopticalcommunicationtechnology,peoplehaveconsideredandtriedavarietyoftransmissionmedia,includingtheusemadeofglassopticalfibertotransmitlightsignals,butthebestwasthelossofopticalglassmaterialin1000dB/kmabove,suchahightransmissionlosscannotbeuseds