《光通信技術(shù)》課件：Lecture-導(dǎo)論

DepartmentofOpticalEngineering,ZJUFiber-OpticCommunicationsTechnologyHistoricalPerspectiveSmoke<1500Semaphoredevice1500-1800Mechaniccoding1792ClaudeChappeDepartmentofOpticalEngineering,ZJUOptoelectronicTechnologyinOurLifeEverydayDepartmentofOpticalEngineering,ZJUIntroductionWhygodigital?Advantage:

lessmisinterpretationDisadvantage: requiresmorechannelcapacityMajordemandHighercapacityLowercostDepartmentofOpticalEngineering,ZJUShannon-HartleytheoremCapacityv.s.bandwidth(1948)Capacity(bits/sec)=BW(Hz)xlog2(1+SNR)Channelbandwidthv.s.Carrier-signalfreq

Channelbandwidth(Hz)

0.1XCarrier-signalfreq.(Hz)DepartmentofOpticalEngineering,ZJUFromcopperwiretoopticalfiberCarrier-signalfreq.limit:Copperwire 1MHzCoaxialcable 100MHzRadiofreq. 500KHzto100MHzMicrowave: 100GHzLight: 100-1000THz!DepartmentofOpticalEngineering,ZJUDepartmentofOpticalEngineering,2008CapacityofCommercialLightwaveSystemsDoubledAnnuallyWorldrecordcapacity2012WorldRecordindatatransmissionoverasinglefiber1Petabitpersecondfibertransmissionover50kilometershasbeenachievedincollaborationbetweenNipponTelegraphandTelephoneCorporation,FujikuraLtd.,HokkaidoUniversity,Japan,andDTUFotonik’sHigh-SpeedOpticalCommunicationsGroup(HSOC).Thistechnologymakesitpossibletosend5000HDTVvideospersecondoverasinglefiber!DepartmentofOpticalEngineering,2008EnablingTechnologiesforOpticComm.Threemajordevelopmentsareresponsibleforrejuvenationofoptics&itsapplicationinmoderntechnology:

1-InventionofLaser2-Fabricationoflow-lossopticalFiber3-DevelopmentofSemiconductorOpticalDeviceAsaresult,newdisciplineshaveemerged&newtermsdescribingthemhavecomeintouse,suchas:-Electro-Optics:isgenerallyreservedforopticaldevicesinwhichelectricaleffectsplayarole,suchaslasers,electro-opticmodulators&switches.DepartmentofOpticalEngineering,2008DepartmentofOpticalEngineering,ZJUWhyOpticalCommunications?Extremelywidebandwidth:highcarrierfrequency(awavelengthof1552.5nmcorrespondstoacenterfrequencyof193.1THz!)ordersofmagnitudeincreaseinavailabletransmissionbandwidth&largerinformationcapacity.OpticalFiberssmallsize&lightweight.immunetoelectromagneticinterference(highvoltagetransmissionlines,radarsystems,powerelectronicsystems,airbornesystems,…)lowEMIcrosstalkbetweenchannelsAvailabilityofverylowlossFibers(0.25to0.3dB/km),highperformanceactive&passivephotoniccomponentssuchastunablelasers,verysensitivephoto-detectors,couplers,filters,LowcostsystemsfordataratesinexcessofGbit/s.DepartmentofOpticalEngineering,2008ThreegreatinventionsLaserFiberAmplifierFiveGenerationsInformationrevolution:internetOver420,000kmofunderseafibertojoinustogetherLow-lossfiber:30yearsofendeavor10%oflightremainsafter50kmtravelinginfiber19695dBat850nmImagetransmittedviaopticalinter-satellitelinkSatelliteconstellationnetworksFromMarstoEarthOpticalCommunicationforComputingOpticalInterconnectsParallelTx/Rxforlinks>10Gb/sIntelOpticalCablesDepartmentofOpticalEngineering,2008BWdemandsincommunicationsystemsType&applicationsFormatUncompressedCompressedVoice,digitaltelegraphy4kHzvoice64kbps16-32kbpsAudio16-24kHz512-748kbps32-384kbps(MPEG,MP3)Videoconferencing176X144or352X288frames@10-30frames/s2-35.6Mbps64kbps-1.544Mbps(H.261coding)Datatransfer,E-commerce,Videoentertainment1-10MbpsFull-motionbroadcastvideo720X480frames@30frames/s249Mbps2-6Mbps(MPEG-2)HDTV1920X1080frame@30frames/s1.6Gbps19-38Mbps(MPEG-2)SystemsConceptsOpticalCommunicationsystemuseseveralMultiplexingtechniques;allincludeTDM(TimeDivisionMultiplexing)TDMstandards(SONET,SDH):ex.OC-192=STM-64=10Gb/sModulationisISK–IntensityShiftedKeyingandNRZformatDWDMsystemsuseGb/slasersatdifferentwavelengthsAggregatedbitrate=NxBChannelspacing50-100GHz;ITUgridTotalopticalbandwidthlimitedbybandwidthofopticalamplifiersWDM:Wavelength-DivisionMultiplexingWDMcombinesmultiplesignalsintoasinglefiberbytransmittingsignalatdifferentwavelengthsSinglechannelcapacity40Gb/s,nchannelsn40Gb/sDepartmentofOpticalEngineering,2008EarlyapplicationoffiberopticcommunicationDigitallinkconsistingoftime-division-multiplexing(TDM)of64kbpsvoicechannels(early1980).OpticalFibercommunications,3rded.,G.Keiser,McGrawHill,2000DepartmentofOpticalEngineering,2008SONET&SDHStandardsSONET(SynchronousOpticalNETwork)isthenetworkstandardusedinnorthAmericaSDH(SynchronousDigitalHierarchy)isusedinotherpartsoftheworld.Thesedefineasynchronousframestructureforsendingmultiplexeddigitaltrafficoverfiberoptictrunklines.ThebasicbuildingblockofSONETiscalledSTS-1(SynchronousTransportSignal)with51.84Mbpsdatarate.Higher-rateSONETsignalsareobtainedbybyte-interleavingNSTS-1frames,whicharescramble&convertedtoanOpticalCarrierLevelN(OC-N)signal.ThebasicbuildingblockofSDHiscalledSTM-1(SynchronousTransportModule)with155.52Mbpsdatarate.Higher-rateSDHsignalsareachievedbysynchronouslymultiplexingNdifferentSTM-1toformSTM-Nsignal.DepartmentofOpticalEngineering,2008SONET&SDHtransmissionratesSONETlevelElectricallevelLinerate(Mb/s)SDHequivalentOC-1STS-151.84-OC-3STS-3155.52STM-1OC-12STS-12622.08STM-4OC-24STS-241244.16STM-8OC-48STS-482488.32STM-16OC-96STS-964976.64STM-32OC-192STS-1929953.28STM-64OpticalFibercommunications,3rded.,G.Keiser,McGrawHill,2000DepartmentofOpticalEngineering,2008GlobalOpticalCommunicationsRevenueandProjectionDepartmentofOpticalEngineering,2008NetworkTraffic:TheShifttoDataDepartmentofOpticalEngineering,2008TypicalFiberOpticalCommunicationSystemDepartmentofOpticalEngineering,2008InstallationofFiberopticsDepartmentofOpticalEngineering,2008OpticalFibercommunications,3rded.,G.Keiser,McGrawHill,2000DepartmentofOpticalEngineering,2008PartsforFiber-opticCommunicationSystemsTransmission-fibercableMux/DemuxAdd/DropmultiplexerAmplificationOpticalMonitoringSwitchingCoupling/SplittingConnectorsOpticalFibersDepartmentofOpticalEngineering,2008HomeworkProblemsforchapter1-3Reviewthesummaryofeachchapter2.6,2.73.12,3.22,3.25,3.7,3.21,3.29,3.30,3.47DepartmentofOpticalEngineering,2008PartsforFiber-opticCommunicationSystemsConnectorsDepartmentofOpticalEngineering,2008PartsforFiber-opticCommunicationSystemsTransceiver,FiberChannelandGigabitEthernet,SmallFormFactor

KeyFeatures1.GigabitEthernetandFibreChannelperformancecapabilitiesinasinglecomponentShort(850nm)andlong(1310nm)wavelengthoperationSingle3.3Vpowersupply(150mAtypical)HighreliabilityLowbiterrorrateDepartmentofOpticalEngineering,2008PartsforFiber-opticCommunicationSystems10Gb/sTransponder,TDM/DWDM,SmallFormFactor

KeyFeaturesThreeconfigurationsTDMSR2/IR2/LR2(25,40,80km)SupportsDWDMSmallformfactor(2.2”x3.0”x0.53”)Lowpowerconsumption:4.8Wtypical,6.8WmaximumforTDM70CmaxoperatingtemperatureHighsensitivityPINorAPDreceiversDepartmentofOpticalEngineering,2008PartsforFiber-opticCommunicationSystemsMUX/DEMUX:AWG,100GHz40ChannelDepartmentofOpticalEngineering,2008PartsforFiber-opticCommunicationSystemsCommunicationmodule:20dBm,ControlledEDFAKeyFeatures:Variablegain,10to26dBVariableopticalattenuator(VOA)Constantgain,power,andcurrentmodeAlarmsDepartmentofOpticalEngineering,2008PartsforFiber-opticCommunicationSystemsSwitch1x4and1x8bidirectionallatchingconfigurationsHermeticpackageLowinsertionlossNull(blocking)stateDepartmentofOpticalEngineering,2008TelecomBubblesDepartmentofOpticalEngineering,2008TelecomMarketMainlandChinaFiberMarketGrowth:~12%/yearDepartmentofOpticalEngineering,2008ConsolidationofTelecomSuppliersDepartmentofOpticalEngineering,2008OpticalFibersGuidedlightTotalinternalreflectionRefractiveindexν=c/nPuresilicancld=1.4572AddingGeO2toincrease

n,B2O3tolowernCriticalangleofpropagation

αc=arcsin[1-(ncld/ncore)2]1/2Acceptanceangle

nasinΘa=ncoresinαcNumericalaperture

NA=sinΘaDepartmentofOpticalEngineering,2008SingleModeFiberSMfiberexampleDepartmentofOpticalEngineering,2008AttenuationDefinition:DecreaseinlightpowerduringlightpropagationalonganopticalfiberReasons:Bendinglosses–resultingfromchangeinindexprofileMicrobending–testedonsandpaperMacrobending–e.g.diameter31-50mmcoilsScatteringAbsorptionDepartmentofOpticalEngineering,2008AttenuationCalculationDefinition:Loss=Pout/Pin Loss(dB)=10log(Pout/Pin)1dBloss=20%loss0.5dBloss=10.9%lossLoss(dBforLkm)=loss(dBperkm)L(km)Example:@1.55μmsmf:0.2dB/kmUnits:PowerindBm=10log(P/1mW)Example0dBm=1mW1dBm=1.25mW10dBm=10mW

Loss=Pout(dBm)-Pin(dBm)DepartmentofOpticalEngineering,2008ThreetypesofFiber:SI,GI,andSM(step-index,gradient-index,single-mode)Phenomenon:

Lightcanpropagateinsideanopticalfiberonlyasasetofseparatebeams(rays),atdistinctpropagatingangles,,rangingfromzerotoc.Modes:thesedifferentbeams

N=V2/2step-index N=V2/4graded-index

Vnumber=dN.A./

ExamplePhysicsofmodes:1.wave2.differentmodesdifferentphaseshifts3.fibersupportsonlycertainwavesDispersion:intermodalandchromaticDepartmentofOpticalEngineering,2008LossindBv.s.PercentLossDepartmentofOpticalEngineering,2008GIFiberModeNumberDepartmentofOpticalEngineering,2008ModalDispersioninSIfiberSIfiberpulsespreadbymodaldispersionFastpath:straightlinet0=L/v,v=c/n1Slowpath:zig-zaglinestc=L/vcoscSpread:tSI=tc-t0=(Ln1/c),=(n1-n2)/n2tSI/L=400ns/kmSIfiberMaximumbitrate1/tSI=12Mbits/snotimpressiveexampleDepartmentofOpticalEngineering,2008GradedIndex(GI)fiberTh