《光纖通信課程設(shè)計》課件：Class3-03

FiberOpticNetworkDesignX.Wu,M.J.Li,H.M.YanDept.ofOpt.Engr.,ZJU2011Class3Outline

ChromaticdispersioneffectDispersioncompensatingtechniquesOptimizationofresidualdispersionoritsmap010011timefcarrierfreq.ViVjVkFourier?InformationBandwidthofData?TemporalSpreadingf(distance,(bitrate)2)(ps/nm)/kmtimeFibertimePhotonVelocity(f)=SpeedofLightinVacuumIndexofRefraction(f)SignalDegradation

ControlPacket(C.P.),notpayload,isregeneratedateverynodeC.P.haslowerbit-rate(C.D.effect(bit-rate)2)ThereishigherchanceforpayloadtobedegradedNodeNodeNodeNodettttPayloadC.P.EffectonPayloadandControlPacketPolarization-mode-dispersion(PMD)Polarizationdependentloss(PDL)Degradationbasedonnon-catastrophiceventsRandompolarizationcouplingStatisticallyvarieswithtimeBit-rateandwavelengthdependentPolarizationstategenerallyunknownandwandersPMDImpairmentcrosssectionEllipticalFiberCoresideview

PMDinducesrandomlychangingdegradations.Criticallimitationat

10Gbit/spayloaddatarates.The2polarizationmodespropagateatdifferentspeeds.1st-orderPMD=DGDPMD(A)(B)DGDPMDCausesandStatisticalEffectHowmanysegmentswillbeenoughtoemulatePMD?Ans.=~12PoincareSphere&PrincipleStateofPolarizationPrincipleStateofPolarizationProved1986BellLabsC.D.Poole&R.E.WagnerTwoPSPperpendiculartoeachotherindependentofwavelengthtothefirst-orderPSPinPoincareSphere&PrincipleStateofPolarization球面上的每一個點都代表了一種橢圓偏振態(tài)，在兩極演化為右旋、左旋圓偏振光，在赤道退化為線偏振光，北半球為右旋偏振態(tài)，南半球為左旋偏振態(tài)。所以，偏振光在光纖傳輸過程中的任意偏振態(tài)的變化都可以表示成邦加球上的某一條運動軌跡

PMDtemporalchangesmorerapidlywiththefiberlengthandaverageDGDFrequencyofoccurrenceinducedbyPMDfluctuationTimeSpan(ms)Occurrence52kmfiber<>=2.8ps(b)FastFluctuation

Mechanicalvibrations:millisecondstominutesH.Bulow,etal.,OFC1999TimeRateofPMDChangePMD(ps)1.52.02.5101418Temp.(C)Time(min)040080048.8kmburiedcable(a)SlowFluctuation

PMDvariationsduetotemperaturechanges:hourstodaysJ.Cameron,etal.,OFC1998PMDMonitoringTechniquesRequireshigh-speeddevices(demonstratedfor160Gb/sRZsignal)Affectedbyotherdistortionsources+CanbeintegratedwithelectronicequalizationA.EyeopeningmeasurementB.RFspectrumanalysis

+Nohighspeedelectronics+DependsonlyonPMD+Bit-rateindependent+UnaffectedbyotherdistortionsourcesPulse-widthdependentC.

Degreeofpolarization(DOP)measurement+SimpleAffectedbyotherdistortionsourcesSensitivityandDGDrangedependsonmonitoredfrequencyPMDonaninstalledfiberlinkGoalTogainanunderstandingofthetemporalandspectralcharacteristicsofPMDonaninstalledfiberlink.ApproachMakelong-termmeasurementsofthedifferentialgroupdelay(DGDor)overarangeofwavelengthsandassessitsratesofchangewithtimeand.DesiredoutcomeProvidenetworkoperatorswithknowledgetoevaluatetechniquesformitigatingPMD-inducedoutageswhenchanneldataPCforRemoteControl&DataStorageTunableLaserSource(TLS)(1510–1625nm)Dl=0.1nmPolarizationAnalyzer(PA)(JonesMatrixEigenAnalysis)InstrumentController

Fiberloopback:95-kmspan

ofslotted-core,directburiedfiber-opticcablemadeavailablebySprint.Over86days(fromNovember9,2001thruFebruary2,2002)692measurementsweremadeonthe1150discretewavelengths.Measurementswererepeatedaboutevery3hours.PMDCharacterization86daysofdata795,800dataptsObservationsDGDdependsonbothtimeand.DGDvariesslowlywithtime.DGDvariesrapidly

with.InstancesofhighDGDarespectrallylocalized.PMDcharacterization:DGDvs.landtimePMDcharacterization:Probabilitydensityfunction

ObservationsMeasureddatashowgoodagreementwithMaxwelliandistribution.ThereisalowprobabilityofhighDGDevents(i.e.,DGD>3meanDGD).Theoreticalresultsfromoutagemodel:RxThreshold 3<DGD> 3.7<DGD>Span1MTBO 6.39years 1648years!!!Outageduration136minutes 108minutesMTBOs:meantimebetweenoutagesPMDcharacterization:resultsandconclusionsFiberSim:

SMF/LeafComparison75km75km10Gb/sperchannel25channels75kmDCF/EDFADCF/EDFA...DCF/EDFARxTxDifferentFibers:

EyeDiagramsvs.Distance@75km@450km@750km@1050kmSSMFLinkNZDSFLinkCompensationConfigurationsOutputInputSqueezers(00)Squeezers(450)OpticalFiberABCDEPMFEfficientopticalmodulationformats:WDM+SCMOpticalMUXAdd/dropTransmitter1f1Sf2ch.2fnch.n..l1LDch.1lml1f1Sf2ch.2fnch.n..Receiver1ch.1OpticalDMUXf1Sf2ch.2fnch.n..Receivermch.1Transmittermf1Sf2ch.2fnch.n..lmch.1LDEfficientopticalmodulationformats:

CombatPMD-inducedsignalfading

usingdiversitySCMreceiverTxPolarizationcontrollerRFdetectionSLPFAmp.ControlalgorithmTodecisioncircuitSpliterPBSRFdetectionPD1(b)P