《光纤通信课程设计》课件：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球面上的每一个点都代表了一种椭圆偏振态，在两极演化为右旋、左旋圆偏振光，在赤道退化为线偏振光，北半球为右旋偏振态，南半球为左旋偏振态。所以，偏振光在光纤传输过程中的任意偏振态的变化都可以表示成邦加球上的某一条运动轨迹

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