光有源器件介绍

光有源器件

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光无源器件光器件：光通信网络的基础光有源器件定义：需要外加能源驱动工作的光电子器件半导体光源(LD,LED,DFB,QW,SQW,VCSEL)半导体光探测器(PD,PIN,APD）光纤激光器（OFL:单波长、多波长）光放大器(SOA,EDFA)光波长转换器(XGM,XPM,FWM)光调制器（EA）光开关/路由器光无源器件定义：不需要外加能源驱动工作的光电子器件光纤连接器（固定、活动,FC/PC,FC/APC）光纤定向耦合器/分支器光分插复用器（OADM)光波分/密集波分复用器（WDM/DWDM)光衰减器（固定、连续）光滤波器（带通、带阻）光纤隔离器与环行器（偏振有关、无关）光偏振态控制器、光纤延迟线、光纤光栅光器件与电器件的类比多波长光源DWDM光调制器光隔离器光耦合器光波长转换光放大DWDM光色散补偿光隔离器光环行器光波长转换OADMDWDM光隔离器光环行器光开关光器件的应用可调谐滤波DWDMOXC光耦合器光调制解调光器件的分类光电变换器件光开关与调制器件光放大器件光色散补偿器件光网络器件光电变换器件F-P腔激光二极管(LD)分布反馈布拉格激光器(DFB)分布布拉格反射激光器(DBR)外腔激光器与Q开关激光器发光二极管(LED)光纤激光器(OFL)垂直腔表面发射激光器(ECSEL)多波长光源与波长可调谐激光器光电探测器(PD、PIN、APD)

光调制器件幅度调制机械调制电光调制直接调制电吸收光调制(EA)相位调制偏振调制光电集成芯片(OEIC)光子集成芯片(PIC)光放大器件掺铒光纤放大(EDFA)掺镨光纤放大(PDFA)掺钕光纤放大(NDFA)分布式光纤放大喇曼光纤放大(SRFA)布里渊光纤放大(SBFA)半导体光放大(SOA)

光色散补偿器件色散控制色散位移单模光纤非零色散位移单模光纤大有效截面单模光纤色散平坦单模光纤色散补偿色散补偿光纤模块SOA色散补偿光纤光栅色散补偿色散管理光网络器件光耦合透镜（自聚焦透镜、玻璃球透镜）光连接器与光耦合器光隔离器与光环行器光滤波与光波分复用器件光起偏器与偏振控制器光波长转换与光波长路由器件光调制解调器（Modem）光衰减器与光延时器件光开关与光交叉连接器件微光电机械芯片元件：Components器件：Devices模块：Modules系统：SystemsOpticalComponentTechnologiesOpticalfibretechnologyMicrooptictechnologyPlanarwaveguidetechnologyMicro-Optic-Electronic-MechanictechnologyFibreTechnology

Fibreisnotonlyatransmissionmedium.Manydevicessuchasamplifiersandfilterscanbemadefromfibre.Componentsusuallyendupconnectedtoafibrefortransmission.Microoptics

Devicesaremadeusingtraditionalopticalcomponents(suchaslenses,prismsanddiffractiongratings)assembledtogether.Makingverysmall,veryhighprecisioncomponentsandassemblingthemintousefuldevicestotoleranceswelllessthanonemicronisverydifficultandexpensivetoaccomplish.PlanarWaveguideTechnology

Devicesareconstructedonthesurfaceofaflatpieceofmaterialsuchassilicaorsemiconductorcrystalusingthetechniquesofsemiconductorchipmanufacturing.PlanarOpticalDevicesAdvantagesBuildadevicesmuchmoreefficientlyandwithmuchlowercost.Physicallyquitesmallandbebuiltwithverygreatprecision.CriticaldimensionscanbecontrolledmuchmoreaccuratelyThereareanumberofdevicesthatcan'tbebuiltanyotherway.Manydevicescanbemadetogetheronasinglelargesubstrateandlatercutupintoindividualdevices.DifficultiesNeedtocontroldimensionsaccuratelytoabout.25ofamicron.Whendiagonalwaveguideshaveregularlyccurringstepsintheirsides,youhappentochanceonaresonantwavelength.Manycomplexdevicescan'tbedoneinplanartechnologybecauseaplanardeviceismadefromauniformmaterial.Itiscostlyanddifficulttoconnectthesedevicestofibres.Fabricationof

PlanarOpticalDevicesDiffusionofadopantintoaflatubstrate.Deposition/etchingtechniquessimilartothoseusedinmakingsemiconductors.Directwritingofwaveguidesusingapowerfullaserbeamandphotosensitivedopantinthematerial(suchasgermaniuminsilicaglass).Deposition/Etching

DiffusionTechniques

Asilicaorglasssubstrate(ratherthanasiliconone)isused.Thesurfaceiscoveredwithamasktocoverthepartsofthedevicethatwedon'twanttobecomewaveguiding.Theblankisthensubjectedtoprolongedexposure(usuallyatahightemperature)toamaterialwhichcandiffuseitswayintothesurfaceandsoformawaveguide.IonExchangeTechniquesAnexampleoftheionexchangetechniquewouldbewheresodaglass(withahighsodiumcontent)isusedasthesubstrate.Aftermasking,thesubstrateisimmersedinmoltenpotassiumnitrate.Potassiumionsdiffuseintotheunmaskedpartsoftheglassandsodiumionsdiffuseout.Thustheionsareexchanged-KreplacesNa.thisincreasestheRIandformsawaveguide.DirectWritingwith

aUVBeam

Asmallsheetoffusedsilicadopedwithgermaniumisused.This“blank”ispolisheduntilthesurfaceisveryflat.AUVlaserbeam(244nm)atveryhighintensityisthenusedtoexposetheareasonthesurfacethataretobeofhigherRI.OpticalAmplifiersWhatisanOpticalAmplifierAnopticalamplifierisadevicewhichamplifiestheopticalsignaldirectlywithouteverchangingittoelectricity.Thelightitselfisamplified.HowtomakeanOAAmplifierscanbebuiltinsemiconductor:SemiconductorOpticalAmplifiers(SOAs).Almostanysemiconductorlasercanbemadeintoanamplifierwithafewmodifications-

Amplifierscanbebuiltinfibres:FibreAmplifiersEDFA:ErbiumDopedFibreAmplifiers PDFA:PraseodymiumDopedFibreAmplifiersNDFA:NeodymimumDopedFibreAmplifiersSRFA:StimulatedRamanFibreAmplifiersPFA:PlasticFibreAmplifierPrinciplePumpingEnergySignalinSignalout1550EDFA增益窗口30nm~60nm光放大器增益光纤衰减除去OH峰外>300nm低损耗窗口波长nm8501310PDFASOASRADevelopmentofOAEDFA增益窗口30nm~60nmPDFASOASRAEDFAsEnergyLevelStates

ofErbium

TechnicalCharacteristics

ofEDFAsEfficientpumpingMinimalpolarisationsensitivityLowinsertionlossHighoutputpower(thisisnotgainbutrawamountofpossibleoutputpower)LownoiseVeryhighsensitivityLowdistortionandminimalinterchannelcrosstalkDefinitionsGain(amplifier):theratioindecibelsofinputpowertooutputpower.GainCoefficient:thesmallsignalgaindividedbythepumppower.Bandwidth:therangeofwavelengthsoverwhichtheamplifierwilloperate.DefinitionsGainSaturation:thepointwhereanincreaseininputpowerceasestoresultinanincreaseinoutputpower.

PolarisationSensitivity:thedifferenceingainofaninputsignalinonepolarisationtothegainintheorthogonalpolarisation.(typical.01~.1dB).NoiseFigure:theratiooftheSNRattheinputtotheSNRattheoutput(indecibels).GainCharacteristicsofEDFAsResponseofCascadedEDFAsFlatteningtheGainCurveOperatingthedeviceat77oK.Introducingotherdopantmaterials(suchasaluminiumorytterbium)alongwiththeerbiumintothefibrecore.Amplifierlengthisanotherfactorinfluencingtheflatnessofthegaincurve.Controllingthepumppower(throughafeedbackloop)isroutinetoreduceASE.

FlatteningtheGainCurveAddinganextraWDMchannellocallyattheamplifier.Thisiscalled“gainclamping”.Manipulatingtheshapeofthefibrewaveguidewithintheamplifier.Fibreswithdualcoreshaverecentlybeenshowntoproducemuchsuperiorgainflatnesscharacteristics.FlatteningtheGainCurveUsing“blazed”fibreBragggratingsasfilterstoreducethepeaksintheresponsecurve.Inotherwords,reducetheresponseatallwavelengthstothatoftheworstwavelength.Thisapproachhasbeenreportedtoworkwellinfieldtrials.Usingchannelpreemphasisonthesignalsastheyaretransmitted.Thatis,transmitdifferentWDMchannelsatdifferentpowerlevelstocompensateforlateramplifiergaincharacteristics.LPG

for

FlatteningtheGain

GainClampingEDFACouplerFilterCouplerEDFA光放大器增益锁定技术泵浦源功率控制饱和光控制技术光功率检测控制输入光功率检测输出光功率检测PinPout泵浦激光器EDFWidebandEDFAsusualgainwindow(S-&C-band)1525-1565nmSecondgainwindow(L-band)1570-1610nmUsingco-dopants,principallyaluminiumandphosphorusWidebandEDFAs

80nm.GainSaturationCo-DopantsCommonco-dopantsusedarealuminium(Al),ytterbium(Yb)andgermanium(Ge).Geco-dopingproduces1536nmand1550nmgainpeaks.Albroadensandflattensthegainspectrumintheregion1540nmto1560nm.DesignofAmplifierLengthBoththesignalpowerlevelandthepumppowerlevelvaryalongthelengthoftheamplifier:signaltravelsstronger;pumppowerleveldecreases.Singlewavelengthoperation:

Lopt=f(Psig,Ppump,Ce,G)WDMoperation:theflatnessofthegain.Thegainspectrumatanypointalongtheamplifierwillbedifferentfromthespectrumatanyotherpointalongtheamplifier.SelectPumpWavelengths980nmisalmosttwiceasefficient,asapumpwavelength,than1480nm.1480iswithinthegainspectrum1480isatwo-levellasersystem1480istemperature-sensitivedisadvantageof980nm:quitenarrowpumpbandwidthWarningPumpsneedtoproduceanoutputofupto250mW.UnlessthelaserisverycarefullydesignedtoprotectityoucanburntheendfacetanderodetheLD.PumpingDirectionCladdingPumpsOutputpowersofupto10watts!MultiStageEDFAs1)Toincreasethepoweroutputwhilstretaininglownoise2)Toflattenthetotalamplifiergainresponse3)ToreduceASEnoiseRemotePumpingTwofibresareusedintheconnection-oneforthesignalandoneforthepump.topumpat1480nmInatypicalunderseasystemtoextendthedistance

fromaround100kmto150oreven200km.EDFASystemResilienceSignalpassesthroughthefailedamplifierrelativelyunchanged!UsingOTDRsinAmplifiedLinksTodiagnoselinkconditionrightthroughtheamplifier.AmplifierApplicationsPreamplifiersPowerAmplifiersLineAmplifiersSecond-GenerationEDFAsAnamplifierwithanyofthefollowingcharacteristicsis“second-generation”:Multi-stagedesignsUseofco-dopantssuchasytterbiumUseofmultiplepumpsUseofgain-equalisationtechniquesSummaryofEDFACharacteristicsItissignificantlysimplerthanarepeaterandwillhaveamuchlongermeantimetofailure.Itissignificantlylowerincostthanarepeater.Itwilloperateatalmostanyspeed.Itcanbemadephysicallysmallenoughtofitonaprintedcircuitcard.SummaryofEDFACharacteristicsItwillproduceagaininopticalsignalofabout25dB.Someamplifierscanproduceagainof50dBorevenhigher.Itwillamplifymanydifferentwavelengthssimultaneously(withsomesmalllimitations).SummaryofEDFACharacteristicsBothamplitude(pulse)modulatedandcoherent(frequencymodulated)lightaswellascableTVsignalcouldbeamplifiedwithoutdistortion.Thereise