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1、光纤单模与多模的区别（Differencesbetweensingle-modeandmultimodeopticalfibers）Differencesbetweensingle-modeandmultimodeopticalfibersTheopticalfiberdoesnotradiatetheelectronicsignaloutward,sothenetworkusingopticalfibermediahasimprovedgreatlyintermsofsecurity,reliabilityand
2、networkperformance.Thebandwidthofopticalfibertransmissionismuchhigherthanthatofcoppercable,andthemaximumconnectiondistanceofopticalfibersupportismorethantwokilometers.Itisaninevitablechoicetobuildalargerscalenetwork.Nowtherearetwodifferenttypesoffibers,single-
3、modeandmultimodefibers.Theso-called"mould"referstoabeamoflightenteringthefiberatacertainangle.Multimodefiberuseslight-emittingdiode(LED)aslightemittingdevice,whilesingle-modefiberuseslaserdiode(LD).Multimodefiberallowsmultiplebeamsoflighttopassthroughthefiber.
4、Becausethedifferentlightentersthefiberangleisdifferent,sothetimetoreachtheendofthefiberisalsodifferent.Thisiswhatweusuallycallthemodedispersion.Dispersionlimitsthebandwidthandtransmissiondistanceofmultimodefibertosomeextent.Itisforthisreasonthatmultimodefiberi
5、sgenerallyusedinthesameofficebuildingorinarelativelycloseareaofthenetworkconnection.Singlemodefibersallowonlyonebeamoflighttopassthroughthefiber.Sincethereisonlyonemode,dispersiondoesnotoccur.Usingsinglemodeopticalfibertotransmitdataisofhigherqualityandlongert
6、ransmissiondistance.Singlemodefibersarecommonlyusedtoconnectofficebuildingsorgeographicallydispersednetworks.1.single-modefibercorediameterissmall(10mm),onlyallowsonemodetransmission,thedispersionissmall,workingatlongwavelength(1310nmand1550nm),andthecouplingo
7、fopticaldevicesisrelativelydifficult2.multimodefibercorediameterislarge(62.5mmor50mm),allowinghundredsofmodesoftransmission,dispersion,workingat850nmor1310nm.Withthecouplingofopticaldevicesisrelativelyeasy,andtheopticalmoduleisconcerned,strictlyspeakingisnotdi
8、videdintosingle-mode,multimode.Theso-calledsingle-modeandmultimodeopticalmodulemodule,referstotheopticaldevicesandopticalfiberwithwhichcanobtainthebesttransmissioncharacteristics.G
