专业英语(光电子)-03-1-Components.ppt

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1、OpticalCommunicationTechnologyAndOpticalNetworkingYanheLiDept.ofElectronicEngineering,TsinghuaUniversity2004.9Chapter3ComponentsComponents3.1Couplers3.2IsolatorsandCirculators3.3MultiplexersandFilters3.4OpticalAmplifiers3.5Transmitters3.6Detectors3.7Switches3.8WavelengthConverters3.1C

2、ouplersAdirectioncouplerAdirectionalcouplerisusedtocombineandsplitsignalsinanopticalnetwork.A2x2couplerconsistsoftwoinputportsandoutputports.Construction:fusetwofiberstogetherinthemiddle;usewaveguidesinintegratedoptics.3.1CouplersAcouplercanbeusedasapowersplitterifthecouplinglengthlis

3、adjustedsuchthathalfthepowerfromeachinputappearsateachoutput.Suchcoupleriscalleda3-dBcoupler.Couplersarealsousedtotapoffasmallportionofthepowerfromalightstreamformonitoringpurposesorotherreasons.Couplersarethebuildingblocksforseveralotheropticaldevices.Wewillexploretheuseof3-dBdirecti

4、onalcouplerstoconstructopticalswitched.CouplersarealsotheprinciplecomponentsusedtoconstructMach-Zehnderinterferometers,whichcanbeusedasopticalfiltersandmultiplexers/demultiplexers.3.2IsolatorsandCirculatorsCouplersandmostotherpassiveopticaldevicesarereciprocaldevices,inthatthedevicesw

5、orkexactlythesamewayiftheirinputsandoutputsarereversed.However,inmanysystemsthereisaneedforapassivenonreciprocaldevice.Anisolatorisanexampleofsuchadevice.Itsmainfunctionistoallowtransmissioninonedirectionthroughitbutblockalltransmissionintheotherdirection.Isolatorsareusedinsystemsinfr

6、ontofopticalamplifiersandlasersprimarilytopreventreflectionsfromenteringthesedevices,whichwouldotherwisedegradetheirperformance.Thetwokeyparameters:insertionlossisolationisaround1dB.isaround40to50dB.3.2IsolatorsandCirculatorsThestateofpolarizationoflightpropagatinginasingle-modefiberr

7、eferstotheorientationofitselectricfieldvectoronaplanethatisorthogonaltoitsdirectionofpropagation.Atanytime,theelectronicfieldvectorcanbeexpressedasalinearcombinationofthetwoorthogonallinearpolarizationssupportedbythefiber.Wewillcallthesetwopolarizationmodesthehorizontalandverticalmode

8、s.3.2