原创国际学术会议海报(poster)模板(英文).ppt

原创国际学术会议海报(poster)模板(英文).ppt

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,Figure5:

Reflectionpatternsusingvariousconnectors（reducedFresnelmagnitudesinsideyellowbox）,IntroductionOpticalTimeDomainReflectometry（OTDR）isacommontechniquefordetectingdamageinfiberopticcables.Theprocessinvolvestransmittingapulseoflightdowntheopticalfiber,analyzingtheamountoflightreflectedbacktothesource,anddisplayingthereflectionpatternsontheOTDRscreen.,ConnectorTypeTheindexofrefractionofthepatchvs.thetestfiberwasalloweddifferbyupto10%,whichcreatedamismatchatthejunctionofthetwofibers.Fourtypesofconnectorsweresimulatedtodeterminewhichproducedthelowestreflectionmagnitude.,PlottingthereflectionresponsepatternsfromallfourconnectiontypesshowsthattheAngledPhysicalContactconnectorproducedthelowestreflection（seeFigure6）.Thoughmuchlessexpensive,IndexMatchingFluidonlyhasalifetimeof2years.Mostopticalfiberapplicationsrequire10yearslifeormore3.,References1Sadiku,N.O.Matthew.NumericalTechniquesinElectromagnetics2Newton,StevenA.NovelApproachestoOpticalReflectometry3Knapp,John.CharacterizationofFiber-OpticCablesUsinganOpticalTimeDomainReflectometer（OTDR）,FiberopticcharacterizationusingasimulatedOpticalTime-DomainReflectometer（OTDR）RobbP.MerrillDepartmentofElectricalandComputerEngineering-UniversityofUtah,Duringcharacterizationofshortfiberopticcablesofapproximately1meter,Fresnelreflectionsposeaseriouschallengetoaccuratedamagedetection.TheFresneltailobliteratesanysmallreflectionsthatareproducedbydamagedsectionsofcable,andthedamageisoverlooked.SimulationMethodTheFiniteDifferenceTimeDomainmethod1wasimplementedinMATLABtosimulateapulseoflighttravelingthroughthepatchandtestfibers.ThefollowingparametersusedinthesimulationwereobtainedfromanactualOTDRsystem:

Indexofrefraction（n）oftestfiber=1.4525,Wavelength（）oflightpulse=850nanometers3.PulseDuration,1,Abnormalitiesinthefiber,suchasbends,cracks,connectors,andotherabruptchangesintherefractiveindexcreatereflectionspikescalledFresnel（“Fre-nel”）reflections2.Afteraspikeisdetected,asignificantdelayoccurswhenthereflectometersettlesdownfromitssaturatedstate.ThisdelayiscalledaFresneltail（Figure1）.,Figure3:

SimulatedFresnelTailskews,thenobliterates,thedamagereflectionatlargerdurations,Figure4:

Commontypesoffiberopticconnectorswithrelativereflectionmagnitudesshown,Figure1:

OTDRscreenshotshowingreflectionspikefromcableconnector,andresultingFresneltail（areamarkedbybracket）,Figure2:

Simulatedidealresponseshowingfiberdamage（smallreflectionbumps）.DamageisvisiblebecausenoFres-neltailispresent.,TodeterminetheeffectofthelightpulsedurationonthesaturationleveloftheOTDRunit,oneperiodofaraisedcosinepulsewastransmittedthroughthefiberatvariousfrequencies.Apulsedurationof1microsecondprovedtobethemostfavorablyresponsivefortheparametersofthesimulation（seeFigure3）.Inreal-worldapplication,however,thedurationmustactuallybesmallerduetotherelativelyslowsimulationspeedvs.thephysicalspeedoflight.,SummaryShortfiberopticcablespresentmanychallengesthatmustbeovercomeinordertoaccuratelydetectfiberdamageusingOTDR.Pulsedurationsshorterthan1microsecond,andAngledPhysicalContact（APC）fiberconnectorsarerecommendedtoprovidethegreatestreductioninFresnelreflection.ByperformingOTDRsimulations,anopticalsystemsengineercouldunderstandthebehaviorofafibernetworkanddetectpotentialproblemsbeforeactualproduction.,