《光通信技術(shù)》課件：Lecture1 Introductiondefinition

DepartmentofOpticalEngineering2013Fiber-OpticCommunicationsTechnologyInstructor:X.WuDepartmentofOpticalEngineering,2008CourseOutlineOverviewofPhotonicCommunicationsOpticalFiber:Waveguiding,PropagationModes

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SingleModeFiber-FiberMaterials&FabricationProceduresSignalDegradationinOpticalFibersPhotonicSources&Transmitters:LED&LaserDiodes

-SingleModeLasers,Modulation&NoiseLaser-FiberConnections(PowerLaunching&Coupling)PhotodetectorsDigitalPhotonicReceivers&DigitalTransmissionsystemsWDM&PhotonicNetworksDepartmentofOpticalEngineering,2008Lab&Computer

SimulationsLabsessions

-FiberAttenuationMeasurement-DispersionMeasurement-SpectralAttenuationMeasurementsComputerSimulationsusingPhotonicsoftware-OvertendesignexercisesusingOptiwave

-Covermostlinearandnonlinearphenomena

-ExcellentsystemdesignpracticeDepartmentofOpticalEngineering,2008Introduction/definitionTelecommunicationsWhatisit?

ExchangeofinformationoveradistanceNetconfigurations:

1.point-to-point

2.networks:

a)Meshtopology b)startopology c)ringtopology d)bustopology

DepartmentofOpticalEngineering,2008OptoelectronicTechnologyinOurLifeEverydayDepartmentofOpticalEngineering,2008IntroductionWhygodigital?Advantage:

lessmisinterpretationDisadvantage: requiresmorechannelcapacityMajordemandHighercapacityLowercostDepartmentofOpticalEngineering,2008Shannon-HartleytheoremCapacityv.s.bandwidth(1948)Capacity(bits/sec)=BW(Hz)xlog2(1+SNR)Channelbandwidthv.s.Carrier-signalfreq

Channelbandwidth(Hz)

0.1XCarrier-signalfreq.(Hz)DepartmentofOpticalEngineering,2008FromcopperwiretoopticalfiberCarrier-signalfreq.limit:Copperwire1MHzCoaxialcable100MHzRadiofreq.500KHzto100MHzMicrowave:upto100GHzLight:100-1000THzDepartmentofOpticalEngineering,2008EnablingTechnologiesforOpticComm.Threemajordevelopmentsareresponsibleforrejuvenationofoptics&itsapplicationinmoderntechnology:

1-InventionofLaser2-Fabricationoflow-lossopticalFiber3-DevelopmentofSemiconductorOpticalDevice

Asaresult,newdisciplineshaveemerged&newtermsdescribingthemhavecomeintouse,suchas:-Electro-Optics:isgenerallyreservedforopticaldevicesinwhichelectricaleffectsplayarole,suchaslasers,electro-opticmodulators&switches.DepartmentofOpticalEngineering,2008CapacityofCommercialLightwaveSystemsDoubledAnnuallyDepartmentofOpticalEngineering,2008Categories&Photonics

Optoelectronics:referstodevices&systemsthatareessentiallyelectronicsbutinvolvelights,suchasLED,liquidcrystaldisplays&arrayphotodetectors.QuantumElectronics:isusedinconnectionwithdevices&systemsthatrelyontheinteractionoflightwithmatter,suchaslasers&nonlinearopticaldevices.QuantumOptics:Studiesquantum&coherencepropertiesoflight.LightwaveTechnology:

describessystems&devicesthatareusedinopticalcommunication&signalprocessing.Photonics:inanalogywithelectronics,involvesthecontrolofphotonsinfreespaceandmatter.DepartmentofOpticalEngineering,2008PhotonicCommunicationsPhotonicsreflectstheimportanceofthephotonnatureoflight.Photonics&electronicsclearlyoverlapsinceelectronsoftencontroltheflowofphotons&conversely,photonscontroltheflowofelectrons.ThescopeofPhotonics:1-GenerationofLight

(coherent&incoherent)

2-TransmissionofLight

(throughfreespace,fibers,imagingsystems,waveguides,…)

3-ProcessingofLightSignals

(modulation,switching,amplification,frequencyconversion,…)

4-DetectionofLight

(coherent&incoherent)

PhotonicCommunications:describestheapplicationsofphotonictechnologyincommunicationdevices&systems,suchastransmitters,transmissionmedia,receivers&signalprocessors.DepartmentofOpticalEngineering,2008DepartmentofOpticalEngineering,2008WhyPhotonicCommunications?Extremelywidebandwidth:highcarrierfrequency(awavelengthof1552.5nmcorrespondstoacenterfrequencyof193.1THz!)&consequentlyordersofmagnitudeincreaseinavailabletransmissionbandwidth&largerinformationcapacity.OpticalFibershavesmallsize&lightweight.OpticalFibersareimmunetoelectromagneticinterference(highvoltagetransmissionlines,radarsystems,powerelectronicsystems,airbornesystems,…)LackofEMIcrosstalkbetweenchannelsAvailabilityofverylowlossFibers(0.25to0.3dB/km),highperformanceactive&passivephotoniccomponentssuchastunablelasers,verysensitivephotodetectors,couplers,filters,LowcostsystemsfordataratesinexcessofGbit/s.DepartmentofOpticalEngineering,2008HistoryofFiberOpticalCommunicationDepartmentofOpticalEngineering,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)DepartmentofOpticalEngineering,2008GlobalOpticalCommunicationsRevenueandProjectionDepartmentofOpticalEngineering,2008NetworkTraffic:TheShifttoDataDepartmentofOpticalEngineering,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,2008Evolutionoffiberopticsystems1950s:Imagingapplicationsinmedicine&non-destructivetesting,lighting1960s:Researchonloweringthefiberlossfortelecom.applications.1970s:Developmentoflowlossfibers,semiconductorlightsources&photodetectors1980s:singlemodefibers(OC-3toOC-48)overrepeaterspacingsof40km.1990s:Opticalamplifiers(e.g.EDFA),WDM(wavelengthdivisionmultiplexing)towarddense-WDM.

OpticalFibercommunications,3rded.,G.Keiser,McGrawHill,2000DepartmentofOpticalEngineering,2008Operatingrangeof4keycomponentsinthe3differentopticalwindowsDepartmentofOpticalEngineering,2008MajorelementsOftypicalphotoniccommlinkDepartmentofOpticalEngineering,2008TypicalFiberOpticalCommunicationSystemDepartmentofOpticalEngineering,2008InstallationofFiberopticsDepartmentofOpticalEngineering,2008WDMConceptOpticalFibercommunications,3rded.,G.Keiser,McGrawHill,2000DepartmentofOpticalEngineering,2008OpticalFibercommunications,3rded.,G.Keiser,McGrawHill,2000DepartmentofOpticalEngineering,2008PartsforFiber-opticCommunicationSystemsTransmission-fibercableMux/DemuxAdd/DropmultiplexerAmplificationOpticalMonitoringSwitchingCoupling/SplittingConnectorsOpticalFibersDepartmentofOpticalEngineering,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,2008SingleModeFiberSMfiberexampleClassInteractionIsacceptanceangleameasurementinsidefiber?A:YesB:NoDepartmentofOpticalEngineering,2008DepartmentofOpticalEngineering,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/snotimpressiveexampleDepartmentofOpticalEngineeri