第三章光纖通信器件

光器件：光通信網絡的基礎光有源器件定義：需要外加能源驅動工作的光電子器件半導體光源(LD,LED,DFB,QW,SQW,VCSEL)半導體光探測器(PD,PIN,APD）光纖激光器（OFL:單波長、多波長）光放大器(SOA,EDFA)光波長轉換器(XGM,XPM,FWM)光調制器（EA）光開關/路由器光無源器件定義：不需要外加能源驅動工作的光電子器件光纖連接器（固定、活動,FC/PC,FC/APC）光纖定向耦合器/分支器光分插復用器（OADM)光波分/密集波分復用器（WDM/DWDM)光衰減器（固定、連續）光濾波器（帶通、帶阻）光纖隔離器與環行器（偏振有關、無關）光偏振態控制器、光纖延遲線、光纖光柵光器件與電器件的類比多波長光源DWDM光調制器光隔離器光耦合器光波長轉換光放大DWDM光色散補償光隔離器光環行器光波長轉換OADMDWDM光隔離器光環行器光開關光器件的應用可調諧濾波DWDMOXC光耦合器光調制解調光器件的分類光電變換器件光開關與調制器件光放大器件光色散補償器件光網絡器件光電變換器件F-P腔激光二極管(LD)分布反饋布拉格激光器(DFB)分布布拉格反射激光器(DBR)外腔激光器與Q開關激光器發光二極管(LED)光纖激光器(OFL)垂直腔表面發射激光器(VCSEL)多波長光源與波長可調諧激光器光電探測器(PD、PIN、APD)

光調制器件幅度調制機械調制電光調制直接調制電吸收光調制(EA)相位調制偏振調制光電集成芯片(OEIC)光子集成芯片(PIC)光放大器件摻鉺光纖放大(EDFA)摻鐠光纖放大(PDFA)摻釹光纖放大(NDFA)分布式光纖放大喇曼光纖放大(SRFA)布里淵光纖放大(SBFA)半導體光放大(SOA)

光色散補償器件色散控制色散位移單模光纖非零色散位移單模光纖大有效截面單模光纖色散平坦單模光纖色散補償色散補償光纖模塊SOA色散補償光纖光柵色散補償色散管理光色散補償器件色散補償說明：Differentwavelengthstravelatslightlydifferentspeeds

(thiseffectiscalled“ChromaticDispersion”)Chromaticdispersioncausespulsebroadening

(problemathighbitratesoverlongdistances)Standardsingle-modefiber:1300nmwindowhaslowestCD1550nmlowestloss光網絡器件光耦合透鏡（自聚焦透鏡、玻璃球透鏡）光連接器與光耦合器光隔離器與光環行器光濾波與光波分復用器件光起偏器與偏振控制器光波長轉換與光波長路由器件光調制解調器（OpticalModem）光衰減器與光延時器件光開關與光交叉連接器件微光電機械芯片元件：Components器件：Devices模塊：Modules系統：Systems網絡：Networks光器件技術光纖技術微光學（Microoptics)technology平面波導（Planarwaveguide）技術微光電機械(Micro-Optic-Electronic-Mechanic）技術光纖技術（FibreTechnology）

Fibreisnotonlyatransmissionmedium.

（光纖不僅僅是傳輸媒體）Manydevicessuchasamplifiersandfilterscanbemadefromfibre.（許多器件是由光纖制成，如光纖放大器、濾波器等）Componentsusuallyendupconnectedtoafibrefortransmission.（器件與光纖相連便于傳輸）微光學器件(Microoptics)

器件由傳統的光學元件，如透鏡、棱鏡、衍射光柵等，裝配而成尺寸小，精度高裝配難度高，機械程度低較昂貴平面波導技術

采用半導體芯片制造技術，由硅或其它半導體材料在平板上所形成的器件（Devicesareconstructedonthesurfaceofaflatpieceofmaterialsuchassilicaorsemiconductorcrystalusingthetechniquesofsemiconductorchipmanufacturing)光源和光接收器/Light-emittingDiode(LED)原理：半導體PN結發光（自發輻射光）光譜：寬帶光譜

應用：短距離、小容量數據通信（通過空間/多模光纖傳輸）KeycharacteristicsMostcommonfor780,850,1300nmTotalpoweruptoafewWSpectralwidth30to100nmCoherencelength0.01to0.1mmLittleornotpolarizedLargeNA(poorcouplingintofiber)P-3dBPpeakBW光源和光接收器/FP(Fabry-Perot)Laser

原理：半導體PN結發光＋平行平面反射腔>>>>激光光譜：多縱模光譜（Multiplelongitudinalmode，MLM)

應用：“Classic”semiconductorlaserFirstfiberopticlinks(850or1300nm)Today:short&mediumrangelinksPpeakIPThreshold光源和光接收器/FP(Fabry-Perot)LaserKeycharacteristicsMostcommonfor850or1310nmTotalpoweruptoafewmwSpectralwidth3to20nmModespacing0.7to2nmHighlypolarizedCoherencelength1to100mmSmallNA(goodcouplingintofiber)光源和光接收器/FP(Fabry-Perot)LaseryxzSOP:linearhorizontalSOP:linearvertical偏振（Polarization）說明：Mostlasersarehighlypolarized

Degreeofpolarization(DOP):

DOP=Ppolarized/Ptotal

Stateofpolarization(SOP):

describestheorientation

androtationofthe

polarizedlight

光源和光接收器/分布反饋(DFB)Laser原理：半導體PN結發光＋分布反饋反射腔>>>>激光

光譜：單縱模光譜(Singlelongitudinalmode，SLM)

應用：Highperformancetelecommunicationlaser

Mostexpensive(difficulttomanufacture)Long-haullinks&DWDMsystemsPpeakSMSR光源和光接收器/分布反饋(DFB)LaserKeycharacteristicsMostlyaround1310/1550nmTotalpower3to50mwSpectralwidth10to100MHz(0.08to0.8pm)Sidemodesuppressionratio(SMSR):>50dBCoherencelength1to100mSmallNA(goodcouplingintofiber)光源和光接收器/垂直腔面發光激光器VerticalCavitySurfaceEmittingLasers(VCSEL)DistributedBraggReflector(DBR)MirrorsAlternatinglayersofsemiconductormaterial40to60layers,eachl/4thickBeammatchesopticalacceptanceneedsoffibersmorecloselyKeypropertiesWavelengthrange780to980nm(gigabitethernet)Spectralwidth:<1nmTotalpower:>-10dBmCoherencelength:10cmto10mNumericalaperture:0.2to0.3activen-DBRp-DBROtherLightSourcesWhitelightsourceSpecializedtungstenlightbulbWavelengthrange900to1700nm,Powerdensity0.1to0.4nw/nm(SM),10to25nw/nm(MM)Amplifiedspontaneousemission(ASE)source

“Noise”ofanopticalamplifierwithoutinputsignalWavelengthrange1525to1570nmPowerdensity10to100μw/nmExternalcavitylaserMostcommonfor1550nmband(somefor1310nm)Tunableovermorethan100nm,powerupto10mwSpectrumsimilartoDFBlaser,bandwidth10kHzto1MHzPhotodiodes(光電管）PIN(p-layer,intrinsiclayer,n-layer)Highlylinear,lowdarkcurrentAvalanchephotodiode(APD)Gainuptox100liftsdetectedopticalsignalaboveelectricalnoiseofreceiverBestforhighspeedandhighlysensitivereceiversStrongtemperaturedependenceMaincharacteristicsQuantumefficiency(electrons/photon)DarkcurrentResponsivity(currentvs.L)n+BiasVoltageAPDGainMaterialAspectsSilicon(Si)Leastexpensive

Germanium(Ge)

“Classic”detector

Indiumgalliumarsenide(InGaAs)

HighestspeedWavelengthnm50010001500SiliconGermaniumInGaAsQuantumEfficiency=10.10.51.0Responsivity(A/W)耦合器/分路器

類型*T型耦合器*星型耦合器*定向耦合器*波分復用/解復用器結構*光纖型*微光學器件型主要技術指標*耦合比(CR)*插入損耗(IL)*附加損耗(EL)*方向性（DL)*隔離度（Is)*一致性（U)耦合器/分路器常用耦合器類型

耦合器/分路器●IL(InsertionLoss)IL=-10lgReflectthepowertoeachport.●CR(CouplingRatio)CR=●EL(ExcessLoss)EL=-10lgThetotallossoncoupler

PoutPinPout1Pout1+Pout2Pout1+Pout2Pin耦合器/分路器

DLDL=－10Log(Pj/Pi)

方向性對傳輸系統的影響*同路異向雙信道對傳系統

MXN器件發射1接收2發射2接收1耦合器/分路器*同路同向雙信道傳輸系統

*樹形網傳輸系統

發射1發射2接收2接收1發射1XN光纖型_耦合器/分路器*光纖耦合器光纖型_耦合器/分路器光纖定向耦合星型光纖型_耦合器/分路器光纖型_耦合器/分路器光纖分波/合波光纖型_耦合器/分路器原理單模光纖傳播光纖型耦合器/分路器_耦合理論Equations：

dR/dz-jdR=-jKS; dS/dz+jdS=-jKRAm=Rexp(-jdz);An=Sexp(jdz)Detuningcoefficient：d=(bn-bm)/2

Couplingcoefficient: K光纖型耦合器/分路器_耦合理論方程解

Modecouplingoftwomixedsignal(ofdifferentwavelength)耦合器/分路器_光纖型波分復用/解復用原理

耦合器/分路器_微光學器件型微器件型耦合器耦合器/分路器_波導型波導型耦合器

隔離器（Isolator）:DefinitionAnisolatorisadevicethatallowslighttopassalongafibreinonedirectionbutnotintheoppositedirection.Isolators/應用Mainapplication:Toprotectlasersandopticalamplifiersfromlightcomingback(whichotherwisecancauseinstabilities)

Insertionloss:Lowloss(0.2to2dB)inforwarddirectionHighlossinreversedirection:

20to40dBsinglestage,40to80dBdualstage)

Returnloss:Morethan60dBwithoutconnectorsSimpleIsolator/原理Isolators/工作原理隔離器工作原理

環行器（Circulator）:DefinitionLightenteringatanyparticularport(sayport1)travelsaroundthecirculatorandexitsatthenextport(sayport2).Lightenteringatport2leavesatport3andsoon.Circulators/應用Circulator&chirpedFGBconfiguredtocompensateCDOpticalcrystaltechnologysimilartoisolatorsInsertionloss0.3to1.5dB,isolation20to40dB

Typicalconfiguration:3portdevicePort1 -> Port2Port2 -> Port3Port3 -> Port1Fast

lSlow

l環形器應用：Add/DropNodesFilterreflectsliAddliAdd/DropDielectricthin-filmfilterdesignCirculatorwithFBGdesignCommonPassbandDropliFilterCharacteristicsli-1lili+1PassbandCrosstalkCrosstalkPassbandInsertionlossRippleWavelengths

(peak,center,edges)Bandwidths

(0.5dB,3dB,..)PolarizationdependenceStopbandCrosstalkrejectionBandwidths

(20dB,40dB,..)DielectricFiltersThin-filmcavitiesAlternatingdielectricthin-filmlayerswithdifferentrefractiveindexMultiplereflectionscauseconstructive&destructiveinterferenceVarietyoffiltershapesandbandwidths(0.1to10nm)Insertionloss0.2to2dB,stopbandrejection30to50dBLayersSubstrateIncomingSpectrumReflectedSpectrumTransmittedSpectrum1535nm1555nm0dB30dBTunableFabry-P