光电器件培训教程

Welcome!ShenZhenBESTOPTO.深圳市佰思特光电技术有限公司——光电器件撰写人：郑良桃2005.3.22 Fabry-PerotLaser(FP) DistributedFeedbackLaser(DFB) LightEmittingDiode(LED) VerticalCavitySurface-EmittingLaser(VCSEL) PhotoDiode(PD) Pin-Transimpedance(PIN-TIA) Transceiver Abstract2.Fabry-PerotLaser(FP)ApplicationsATMSONET/SDHFiberChannel 785nmto1550nm.ATMandSONET/SDHapplicationsoperateat1310nm Moderatecost Edge-emittingdevice Operatein“closedloop”mode Moderatespectralwidth Thresholdcurrentscanrangefrom5mAto30mAatroomtemperature Highspeed(dependingondesign)–canbeusedatdataratesfrom155Mbpsto>2.5Gbps Outputcurrent(biasplusmodulation)mustremainabovethelaserthresholdcurrenttoavoidturn-ondelayandoptimizespeed Canbeusedfordistancesto~40kmorlonger Thresholdcurrentandslopeefficiencyvarysignificantlyovertemperature.Therefore,automaticpowercontrol(closedloop)isusedtomaintainaconstantaveragepower(usingamonitordiode)andsomeformoftemperaturecompensationisgenerallyusedforthemodulationcurrent Eyesafetyisnotasbiganissuewith1310nmdevices,butbecomesimportantwithshort-wavelengthdevices(suchas785nm)3.DistributedFeedbackLaser(DFB)ApplicationsATMSONET/SDHFiberChannelDWDM10Gbps 1310or1550nm.WDMapplicationsoperateatseparatewavelengthsaround1550nm Highcost Edge-emittingdevice Operatein“closedloop”mode,SometimeswithTEcoolers InternalBragggratingresultsinverynarrowspectralwidth(SLM) Thresholdcurrentscanrangefrom5mAto30mAatroomtemperature Highspeed(dependingondesign)–canbeusedatdataratesfrom155Mbpsto>2.5Gbps Usedforlongerdistance(~20kmto>100km)/highdataratetransmission Thresholdcurrentandslopeefficiencyvarysignificantlyovertemperature.Therefore,automaticpowercontrol(closedloop)isusedtomaintainaconstantaveragepower(usingamonitordiode)andsomeformoftemperaturecompensationisgenerallyusedforthemodulationcurrent DWDMlasersrequireaccuratetemperaturestabilization–andthereforecontainT/Ecooler,thermistor,laserandwavelengthlocker.4.LightEmittingDiode(LED)Applications FDDI–125Mbps 100MbpsEthernet ATM–155Mbps 266MbpsFibreChannel PlasticFiber 820nmto1320nm,thoughmostapplicationsuse850nmdevices Verylowcost Largebeamdivergenceangle Operatein“openloop”mode Worksacrossmultipledatarates Lowcoupledoutputpower(usually–20to-14dBm) Highdrivecurrent(usually60-100mA) Lowerspeed(typicallyusedatlessthan300Mbps) Highercapacitance Largespectralwidth Devicespeed,outputpower,andspectralwidthlimittheapplicationstolower-speed(typically300Mbps)dataratesatdistancesgenerallylessthan2km5.VerticalCavitySurfaceEmittingLaser(VCSEL)ApplicationsParallelArraysGigabitEthernet/10GbEFiberChannel Shortwavelength(850nm),althoughlongwavelengthareindevelopment Lowcost,Highreliability Surfaceemittingdevice(highyield–canbeopticallytestedbeforedicing) narrowspectralwidth(canbeSLM) Verylowthresholdcurrent(<1mAto7mA) Highspeed(dependingondesign)–canbeusedatdataratesfrom155Mbpsto>10Gbps Outputcurrent(biasplusmodulation)mustremainabovethelaserthresholdcurrenttoavoidturn-ondelayandoptimizespeed Somedeviceexhibitabehaviorcalled“off-statebounce”whichcanresultinslowerfalltimes VCSELs(VerticalCavitySurface-EmittingLasers)includegeometries,circularoutputbeams,highfiberopticcouplingefficiencies,extremelylowpowerconsumption,andhighmodulationrates. ThresholdcurrentvariesmuchlessonaVCSELthananedge-emitting(FPorDFB)laser.However,automaticpowercontrolisstillusedtomaintainaconstantaveragepower(usingamonitordiode)andsomeformoftemperaturecompensationisgenerallyusedforthemodulationcurrent.  Eyesafetyisanissuewith850nmwavelengths.Therefore,safetycircuitryisrequiredinthedriverformostapplicationsinordertomaintaineyesafety--evenwithasingle-pointfault.  OpenloopoperationispossiblewithsomeVCSELs,butmaintainingeyesafetyismoredifficult.6.LaserDiodeCharacteristicsPowerat‘1’/Powerat‘0’=ExtinctionRatio AutomaticPowerControltocontrolaveragepower TemperatureCompensationformodulationLaserCharacteristicMMFPDFBRMSCenterWavelength7.PhotoDiode(PD)PDParameterSensitivitySenVR=1V,1310nm0.800.90A/WVR=1V,1550nm0.850.90A/WDarkcurrentIDVR=5V,T=250C80400PACapacitanceCfF=1MHz,VR=5V0.600.80PFReturnLossRL45dbBandwidthBW-3dB,VR=5V2.5GHzWavelengthλ11001600nmOPTemperature-20+700CSTTemperature-40+800CParameterSymbolTestconditionMin.TypeMax.Unit Sensitivity Darkcurrent(ID)ID=V/RV:VoltageID:Darkcurrent Capacitance(Cf)SignalgenerationOSC10/[（1/2πfC）2+R2]1/2=U/R K=1/2πfCR BandwidthisolatorcoupleropticalpowermeterphotodiodeLaserdBm=10lg(PO/1mW)dB=10lg(PO/PBIAS)RL=10lg(PO/PL) ReturnLoss(RL)8.PIN-Transimpedance(PIN-TIA)9.TransceiverPostAMPTIARDLOSAPDorPINphotodiodeLDdrivercircuitLaserdiodeTDTx_DisableTx_FaultSDASCLDiagnosticMonitoringInterfaceMemoryExtendedID FunctionBlockDiagram Transmitter Po(OutputPower)L=(Po-Sen)/KL:TransmissionInstanceUnit:kmSen:SensitivityUnit:dBmPo:OutputPowerUnit:dBmK:CoefficientofLossUnit:dBm/kmSM:1310nmK=0.4MM:K=41550nmK=0.2 ExtinctionRatioEX=10LogP1/P0EX:ExtinctionRatioUnit:dBP1:istheoutputpowerwhenthesignalis“1”Unit:mWP0:istheoutputpowerwhenthesignalis“0”Unit:mW Transmitteroutputeye Receiver ReceiverSensitivitySensitivityexpressedasaratiooferroredbitstocorrectbits(BER)BERisafunctiononsignaltonoiseratio(SNR)SONETrequiredaBERof10-10GbE/FCrequireaBERof10-12 SaturationPowerTopreventerroredbitontheoutputwhennosignalispresent.IfthepowerinputtedintoPhotoDiodeisverybig,thesignal“1”isdetectedwhenthesignalis“0”infact.100or1 InputSignalDetectionTopreventchatterontheoutputwhennosignalispresent.Thresholdlevelsetbyexternalresistors(definedonrespectivedatasheets).Resistorssetareferencevoltage,whichiscomparedtostagedoutputoflimitingamplifier.1.5to3dBhysteresispresenttoensurethatdataisjammedbeforeBERisviolated. JamBufferInputsetbyasingleexternalpin.ForautomatedoperationforBER,inputdefinedbysignaldetectioncomplimentaryoutputs.StatusofJamwillblockLimitingAmplifieroutputtoPECL/ECLoutputstage.10.ClassofTransceiver PECL/CMLTTL +5V/+3.3V 52M/155M/622M/1.25G/2.5G(SONET/SDH)100M/1.0625G/2.125G(FiberChannel) 1*9/2*9GBIC(GigabitInterfaceConverter)SFP(SmallFormPluggable)2*5/2*10SFF(SmallFormFactor)Thanks!