divisio
Opticalfiberabbreviatedasopticalfiber
Thedivisioofopticalfiber,Forexample:FiberAmplifierorFiberBackboneandsoon.SomepeopleignorethatalthoughFiberhasthemeaningoffiber,itreferstoopticalfiberintheopticalsystem.Therefore,itisobviouslynotadvisabletoliterallytranslatefiberas"fiber"inthedescriptionofsomeopticalproducts.Opticalfiberactuallyreferstoacoremadeoftransparentmaterialandacladdingmadeofamaterialwitharefractiveindexslightlylowerthanthatofthecorearoundit,andtheopticalsignalthatentersthecoreisreflectedbythecladdinginterfacetomakeTheopticalsignalpropagatesinthecoreoftheadvancingmedium.Therearemanytypesofopticalfibers,andtherequiredfunctionsandperformancesvaryaccordingtodifferentuses.However,theprinciplesofdesignandmanufactureofopticalfiberforcableTVandcommunicationarebasicallythesame,suchas:①smallloss;②certainbandwidthandsmalldispersion;③easywiring;④easyintegration;⑤highreliability;⑥manufacturingcomparisonSimple;⑦Inexpensiveandsoon.Thedivisioofopticalfiberismainlysummarizedfromtheworkingwavelength,refractiveindexdistribution, modalità di trasmissione, materia prima e metodo di produzione. tipo, altri (come triangolare, W, concavo, ecc.). (3) Modalità di trasmissione: fibra monomodale (inclusa fibra di mantenimento della polarizzazione e fibra di mantenimento della non polarizzazione), fibra multimodale. (4) Materie prime: vetro di quarzo, vetro multicomponente, plastica, materiali compositi (come il rivestimento in plastica, il nucleo liquido, ecc.), i materiali a infrarossi, ecc. In base al materiale di rivestimento, può essere suddiviso in materiali inorganici (carbonio, ecc.), materiali metallici (rame, nichel, ecc.) e plastica. , ecc., e i metodi di trafilatura includono Rodintube e metodi a doppio crogiolo.
Rudimentum
Silicaopticalfiberisbasedonsilica(SiO2)asthemainrawmaterial,andaccordingtodifferentdopingamounts,tocontrolthecoreandThecladdingoftheopticalfiberwiththerefractiveindexprofile.Quartz(glass)seriesopticalfibershavethecharacteristicsoflowpowerconsumptionandbroadband,andhavebeenwidelyusedincabletelevisionandcommunicationsystems.FluorineDopedFiberisoneofthetypicalproductsofsilicafiber.Generally,asacommunicationfiberinthe1.3Pmwavedomain,thedopantcontrollingthecoreisgermaniumdioxide(GeO2),andthecladdingismadeofSiO.However,mostofthecoresoffluorine-connectedfibersuseSiO2,butfluorineisdopedinthecladding.BecauseRayleighscatteringlossisaphenomenonoflightscatteringcausedbychangesinrefractiveindex.Therefore,itisdesirabletoformadopantthatchangestherefractiveindex,andlessisbetter.ThemainfunctionoffluorineistoreducetherefractiveindexofSiO2.Therefore,itisoftenusedforthedopingofthecladding.Becauseinthefluorine-dopedfiber,thecoredoesnotcontainfluorinedopantsthataffecttherefractiveindex.BecauseitsRayleighscatteringisverysmall,andthelossisclosetothetheoreticalminimum.Therefore,itismostlyusedforlong-distanceopticalsignaltransmission.Comparedwithopticalfibersmadeofotherrawmaterials,SilicaFiberalsohasabroadspectrumoflighttransmissionfromultravioletlighttonear-infraredlight.Inadditiontocommunicationpurposes,itcanalsobeusedinfieldssuchaslightguideandimagetransmission.
Officium
Infraredopticalfiberisusedastheworkingwavelengthofthequartzseriesopticalfiberdevelopedinthefieldofopticalcommunication.Althoughitisusedinashortertransmissiondistance,itcanonlybeusedat2pm.Forthisreason,itcanworkinthefieldoflongerinfraredwavelengths,andthedevelopedopticalfiberiscalledinfraredopticalfiber.InfraredOpticalFiber(InfraredOpticalFiber)ismainlyusedforlightenergytransmission.Forexample,thereare:temperaturemeasurement,thermalimagetransmission,laserscalpelmedicaltreatment,thermalenergyprocessing,etc.Thepenetrationrateisstilllow.
CompoundFiberismixedwithSiO2rawmaterials,suchassodiumoxide(Na2O),boronoxide(B2O2),potassiumoxide(K2O2)andotheroxidemulti-componentglassproductionThecharacteristicofmulti-componentglassisthatthesofteningpointofmulti-componentglassislowerthanthatofquartzandtherefractiveindexdifferencebetweenthecoreandthecladdingisverylarge.Fiberopticendoscopesmainlyusedinmedicalservices.
FluorideFiberChlorideFiber(FluorideFiber)isanopticalfibermadeoffluorideglass.ThiskindofopticalfibermaterialisalsoreferredtoasZBLAN(thatis,zirconiumfluoride(ZrF4),bariumfluoride(BaF2),lanthanumfluoride(LaF3).sub>),aluminumfluoride(AlF3),sodiumfluoride(NaF)andotherfluorideglassrawmaterialssimplifiedintoabbreviations.Mainlyworkintheopticaltransmissionbusinessof2-10μmwavelength.BecauseofZBLANWiththepossibilityofultra-lowlossfiber,thefeasibilitydevelopmentoflong-distancecommunicationfiberisunderway.Forexample,itstheoreticallylowestlosscanreach10-2～10-3dB/kmatawavelengthof3μm,whilequartzfiberItisbetween0.15-0.16dB/Kmat1.55pm.ZBLANfibercanonlybeusedin2.4～2.7μmthermosensorsandthermalimagetransmissionduetothedifficultyofreducingscatteringloss.Recently,inordertouseZBLANforForlong-distancetransmission,1.3μmpraseodymium-dopedfiberamplifier(PDFA)isbeingdeveloped.
PlasticCladFiberuseshigh-puritysilicaglassasthecore,andtherefractiveindexAstep-typeopticalfiberwithplasticssuchassilicagelasthecladding,whichisslightlylowerthanquartz.Comparedwithquartzopticalfiber,ithasthecharacteristicsofcorerentandhighnumericalaperture(NA).Therefore,itiseasytocombinewithlight-emittingdiodeLEDlightsource,andthelossItisalsosmall.Therefore,itisverysuitableforlocalareanetwork(LAN)andshort-distancecommunication.
Plasticopticalfiberisanopticalfibermadeofplastic(polymer)forthecoreandcladding.EarlyproductsweremainlyusedItisusedintheopticalcommunicationofdecorationandlightguidelightingandshort-distanceopticalbonding.Therawmaterialsaremainlyorganicglass(PMMA),polystyrene(PS)andpolycarbonate(PC).ThelossisaffectedbytheinherentC-Hbondingstructureofplastics.Restriction,generallyuptotensofdBperkm.Inordertoreducetheloss,thefluorineseriesplasticsarebeingdevelopedandapplied.Becausethecorediameteroftheplasticopticalfiber(PlasticOpticalfiber)is1000pm,whichis100timeslargerthanthatofthesingle-modequartzfiber,theconnectionissimple,andEasytobendandeasytoconstruct.Inrecentyears,withtheprogressofbroadbandization,thedevelopmentofmultimodeplasticopticalfiberwithgraded(GI)refractiveindexhasattractedsocialattention.Recently,ithasbeenquicklyappliedinautomobileLANandwillbeusedinhomesinthefuture.ItmayalsobeusedinLAN.PSopticalfiberismostlyusedinflowercrafts,crafttoys,electronictoys,andPMMAopticalfiberismostlyusedinlightinganddecoration.
Single-modefibermeansthatitcanonlyThefiberthattransmitsapropagationmodeisusuallyreferredtoasSingleModusFiber(SMF:SingleModusFiber).Itisthemostwidelyusedfiberincabletelevisionandopticalcommunications.Becausethecoreofthefiberisverythin(about10pm)andtherefractiveindexInastep-likedistribution,whenthenormalizedfrequencyVparameter<2.4,intheory,onlysingle-modetransmissioncanbeformed.Inaddition,SMFhasnomulti-modedispersionanddoesnotOnlythetransmissionfrequencybandismoreandthemodefiberiswider,coupledwiththeadditionandcancellationoftheSMFmaterialdispersionandstructuraldispersion,itssynthesischaracteristicjustformsthecharacteristicofzerodispersion,whichmakesthetransmissionfrequencybandwider.InSMF,therearemanytypesduetodifferencesindopantsandmanufacturingmethods.DePr-essedCladFiber(DePr-essedCladFiber),itscladdingformsadoublestructure,andthecladdingadjacenttothecorehasalowerrefractiveindexthantheouterinvertedcladding.Inaddition,therearematchedcladdingfiberswhosecladdingrefractiveindexisuniformlydistributed.
Modus
Multimodefiberreferstothefiberinwhichtheopticalfiberpropagatesintomultiplemodesaccordingtotheworkingwavelengthanditspropagationmodeiscalledmultimodefiber(MMF:MUltiModusFiber).Thecorediameteris50μm,andbecausethetransmissionmodecanreachseveralhundred,comparedwithSMF,thetransmissionbandwidthismainlydominatedbymodaldispersion.Historically,ithasbeenusedforshort-distancetransmissionincabletelevisionandcommunicationsystems.SincetheemergenceofSMFfiber,itseemstohaveformedahistoricalproduct.Butinfact,becauseMMFhasalargercorediameterthanSMFandiseasiertocombinewithlightsourcessuchasLEDs,ithasmoreadvantagesinmanyLANs.Therefore,MMFisstillreceivingattentionagaininthefieldofshort-distancecommunication.WhenMMFisclassifiedaccordingtotherefractiveindexdistribution,therearetwotypes:gradient(GI)typeandstep(SI)type.TherefractiveindexoftheGItypeisthehighestinthecenterofthecore,andgraduallydecreasesalongthecladding.Fromthepointofviewofgeometricoptics,thelightbeamtravelinginthecoreappearstotravelinaserpentineshape.Becausethetimerequiredforeachpathoflightisroughlythesame.Therefore,thetransmissioncapacityislargerthanthatoftheSItype.TherefractiveindexdistributionoftheSItypeMMFfiberandthecorerefractiveindexdistributionarethesame,buttheinterfacewiththecladdingisstepped.AstheSItypelightwaveisreflectedintheopticalfiber,thetimedifferenceofeachlightpathisgenerated,whichcausestheemittedlightwavetobedistortedandthecolorshockislarge.Asaresult,thetransmissionbandwidthisnarrowed,andtheformerSItypeMMFislessused.
Whentheoperatingwavelengthofthedispersion-shiftedfibersingle-modefiberis1.3μm,themodefielddiameterisabout9μm,anditstransmissionlossisabout0.3dB/km.Atthistime,thezero-dispersionwavelengthisexactlyat1.3μm.Amongthequartzopticalfibers,thetransmissionlossinthe1.55pmsectionisthesmallest(about0.2dB/km)fromtherawmaterial.Sincethepracticalerbium-dopedfiberamplifier(EDFA)worksinthe1.55pmband,ifzerodispersioncanbeachievedinthisband,itwillbemoreconducivetotheapplicationoflong-distancetransmissioninthe1.55Pmband.Therefore,cleveruseofthecompositeoffsetcharacteristicsofthedispersionofthequartzmaterialintheopticalfibermaterialandthedispersionofthecorestructurecanmaketheoriginalzerodispersionofthe1.3Pmsection,andtheshifttothe1.55pmsectionalsoconstitutesthezerodispersion.Therefore,itisnamedDispersionShiftedFiber(DSF:DispersionShiftedFiber).Themethodofincreasingstructuraldispersionismainlytoimprovetherefractiveindexdistributionperformanceofthecore.Inthelong-distancetransmissionofopticalcommunication,zerofiberdispersionisimportant,butnottheonlyone.Otherpropertiesincludelowloss,easyconnection,cableformationorsmallchangesincharacteristicsduringwork(includingtheeffectsofbending,stretchingandenvironmentalchanges).DSFisdesignedtoconsiderthesefactorscomprehensively.
Dispersion-flattenedfiberDispersionshiftedfiber(DSF)isasingle-modefiberdesignedwithzerodispersioninthe1.55pmband.Thedispersionflattenedfiber(DFF:DispersionFlattenedFiber)hasawidewavelengthrangefrom1.3Pmto1.55pm.Thedispersioncanbemadeverylow,andthefiberthatachievesalmostzerodispersioniscalledDFF.BecauseDFFhastoreducethedispersionintherangeof1.3μmto1.55μm.Itisnecessarytocarryoutacomplicateddesignfortherefractiveindexdistributionoftheopticalfiber.However,thiskindoffiberisverysuitableforwavelengthdivisionmultiplexing(WDM)lines.BecausetheprocessofDFFfiberismorecomplicated,thecostismoreexpensive.Inthefuture,asoutputincreases,priceswillalsodecrease.
DispersioncompensationfiberFortrunksystemsthatusesingle-modefiber,mostofthemarecomposedoffiberswithzerodispersioninthe1.3μmband.However,thesmallestlossis1.55μm.DuetothepracticaluseofEDFA,itwillbeverybeneficialifthe1.55μmwavelengthcanbeoperatedona1.3μmzero-dispersionfiber.Because,inthe1.3Pmzero-dispersionfiber,thedispersioninthe1.55μmbandisabout16ps/km/nm.Ifasectionoffiberwiththeoppositesignofthedispersionisinsertedinthisopticalfiberline,thedispersionoftheentireopticallinecanbezero.ThefiberusedforthispurposeiscalledDispersionCompensationFiber(DCF:DisPersionCompe-nsationFiber).Comparedwiththestandard1.3μmzero-dispersionfiber,DCFhasathinnercorediameterandalargerrefractiveindexdifference.DCFisalsoanimportantpartofWDMopticallines.
Thelightwavepropagatedintheopticalfiberbythepolarizationmaintainingfiberhasthepropertiesofelectromagneticwave.Therefore,inadditiontothebasiclightwavesinglemode,thereareessentiallytwopositiveelectromagneticfields(TE,TM)distribution.交mode.Generally,becausethestructureofthefibersectioniscircularlysymmetric,thepropagationconstantsofthetwopolarizationmodesareequal,andthetwopolarizedlightsdonotinterferewitheachother.Butinfact,theopticalfiberisnotcompletelycircularlysymmetrical.Forexample,ifthereisacurvedpart,thecombiningfactorsbetweenthetwopolarizationmodeswillappear,whichisirregularlydistributedontheopticalaxis.ThedispersioncausedbythischangeinpolarizedlightiscalledPolarizationModusDispersion(PMD).ForcableTV,whichmainlydistributesimages,theimpactisnottoobig.Butforsomefutureultra-widebandservicesthathavespecialrequirements,suchas:①whenheterodynedetectionisusedincoherentcommunication,andthepolarizationoflightwavesisrequiredtobemorestable;②whentheinputandoutputcharacteristicsofopticalequipmentarerelatedtopolarization;③whenmakingpolarization-maintaininglightWhencouplersandpolarizersordepolarizers,etc.;④Makefibersensorsthatuselightinterference,etc.,wherethepolarizationisrequiredtobekeptconstant,thefiberthathasbeenimprovedtomakethepolarizationstateunchangediscalledpolarizationmaintainingfiber(PMF:PolarizationMaintainingfiber),whichisalsocalledafixedpolarizationfiber.
BirefringentfiberBirefringentfiberreferstoasingle-modefiberthatcantransmittwointrinsicpolarizationmodesorthogonaltoeachother.Becausethephenomenonthattherefractiveindexvarieswiththepolarizationdirectioniscalledbirefringence.Inthemethodofcausingbirefringence.ItisalsocalledPANDAfiber,thatis,Polarization-maintai-ningANDAbsorption-reducingfiber.Itisarrangedintwotransversedirectionsofthecore,withaglasspartwithalargethermalexpansioncoefficientandacircularcross-section.Inthehigh-temperaturefiberdrawingprocess,thesepartsshrink,whichresultsinstretchinginthey-directionofthecore,andatthesametimecompressivestressinthex-direction.Thisresultsinaphotoelasticeffectofthefibermaterial,andadifferenceinrefractiveindexintheXdirectionandtheydirection.Accordingtothisprinciple,thepolarizationremainsconstant.
Opus
Thenormalworkingenvironmenttemperatureofopticalfiberforanti-badenvironmentopticalfibercommunicationcanbebetween-40～+60℃,andthedesignisalsobasedonthepremiseofnotbeingexposedtoalargeamountofradiationof.Incontrast,thefiberthatcanworkinharshenvironmentsthatarecolderorhigher,andcanbeaffectedbyhighpressureorexternalforces,andexposedtoradiationiscalledHardConditionResistantFiber.Generally,inordertomechanicallyprotectthesurfaceoftheopticalfiber,anextralayerofplasticiscoated.However,asthetemperatureincreases,theprotectivefunctionoftheplasticdecreases,whichlimitstheusetemperature.Ifyouswitchtoheat-resistantplastics,suchasTeflon(Teflon)andotherresins,youcanworkat300°C.Therearealsometalssuchasnickel(Ni)andaluminum(Al)coatedonthesurfaceofquartzglass.ThiskindoffiberiscalledHeatResistantFiber(HeatResistantFiber).Inaddition,whentheopticalfiberisirradiatedbyradiation,theopticallosswillincrease.Thisisbecausewhenquartzglassisexposedtoradiation,structuraldefects(alsocalledcolorcenter:ColourCenter)willappearintheglass,andthelosswillincreaseespeciallyatthewavelengthof0.4～0.7pm.ThepreventionmethodistoswitchtoquartzglassdopedwithOHorFelements,whichcansuppressthelossdefectscausedbyradiation.ThiskindoffiberiscalledRadiationResistantFiber,anditismostlyusedinopticalfibermirrorsfornuclearpowerstationmonitoring.
Inordertomaintainthelong-termstabilityofthemechanicalstrengthandlossoftheopticalfiber,theglasssurfaceiscoatedwithinorganicmaterialssuchassiliconcarbide(SiC),titaniumcarbide(TiC),andcarbon(C).Anopticalfiber(HCFHermeticallyCoatedFiber)madetopreventthediffusionofwaterandhydrogenfromtheoutside.Itiscommonlyusedintheproductionprocessofchemicalvapordeposition(CVD)tousecarbonlayerstoaccumulateatahighspeedtoachieveasufficientsealingeffect.Thiscarbon-coatedopticalfiber(CCF)caneffectivelycutofftheintrusionoftheopticalfiberfromexternalhydrogenmolecules.Itisreportedthatitcanbemaintainedfor20yearswithoutincreasinglossinahydrogenenvironmentatroomtemperature.Ofcourse,itispreventingmoistureintrusionanddelayingthefatigueprocessofmechanicalstrength,anditsfatiguecoefficient(FatigueParameter)canreachmorethan200.Therefore,HCFisusedinsystemsthatrequirehighreliabilityinharshenvironments,suchassubmarineopticalcables.
CarbonCoatedFiberThefibercoatedwithcarbonfilmonthesurfaceofsilicafiberiscalledCarbonCoatedFiber(CCF:CarbonCoatedFiber).Themechanismistouseadensecarbonfilmtoisolatethesurfaceoftheopticalfiberfromtheoutsideworldtoimprovethemechanicalfatiguelossoftheopticalfiberandincreasethelossofhydrogenmolecules.CCFisatypeofhermeticcoatedopticalfiber(HCF).
MetalCoatedFiberMetalCoatedFiber(MetalCoatedFiber)isanopticalfibercoatedwithametallayerofNi,Cu,Al,etc.onthesurfaceoftheopticalfiber.Therearealsoplasticcoatingsontheoutsideofthemetallayerforthepurposeofimprovingheatresistanceandbeingavailableforenergizationandwelding.Itisoneoftheopticalfibersresistanttohostileenvironments,andcanalsobeusedasacomponentofelectroniccircuits.Earlyproductsweremadebycoatingmoltenmetalduringthedrawingprocess.Becausethismethodhastoomuchdifferenceinexpansioncoefficientbetweentheglassandthemetal,itwillincreasethesmallbendingloss,andthepracticalrateisnothigh.Recently,duetothesuccessofthelow-lossnon-electrolyticcoatingmethodonthesurfaceoftheglassopticalfiber,theperformancehasbeengreatlyimproved.
Rare-earth-dopedfiberInthecoreofthefiber,thefiberisdopedwithrare-earthelementssuchaserbium(Er),neodymium(Nd),andpraseodymium(Pr).In1985,PayneoftheUniversityofSouthamptonintheUnitedKingdomfirstdiscoveredthatRareEarthDoPedFiber(RareEarthDoPedFiber)hadthephenomenonoflaseroscillationandlightamplification.Therefore,sincethen,theveiloflightamplificationsuchaserbium-dopedhasbeenunveiled.Thepractical1.55pmEDFAistouseerbium-dopedsingle-modefiberanduse1.47pmlaserforexcitationtoobtain1.55pmopticalsignalamplification .Inaddition,praeodymium-dopedfluoridefiberamplifier(PDFA)devolutionis est.
RamanfiberRamaneffectreferstothefactthatwhenmonochromaticlightoffrequencyfisshotintoasubstance,thescatteredlightwillhavefrequenciesoff±fRandf±2fRotherthanfrequencyf.Scatteredlight,thisphenomenoniscalledRamaneffect.Becauseitisproducedbytheenergyexchangebetweenthemolecularmotionofthesubstanceandthelatticemotion.Whenasubstanceabsorbsenergy,thenumberofvibrationsoflightbecomessmaller,andthescatteredlightiscalledstokesline.Conversely,thescatteredlightthatobtainsenergyfrommatterandincreasesthenumberofvibrationsiscalledanti-Stokesline.Therefore,thedeviationFRofthevibrationnumberreflectstheenergylevelandcanshowthevalueinherentinthesubstance.ThefibermadebyusingthisnonlinearmediumiscalledRamanFiber(RF:RamanFiber).Inordertoconfinethelightinthesmallfibercoreforlong-distancepropagation,theinteractioneffectbetweenlightandmatterwillappear,whichcanmakethesignalwaveformundistortedandrealizelong-distancetransmission.Whentheinputlightisenhanced,coherentinducedscatteredlightwillbeobtained.RamanfiberlasersareusedforsensingRamanscatteredlight,whichcanbeusedaspowersourcesforspectroscopicmeasurementandfiberdispersiontesting.Inaddition,inducedRamanscattering,inthelong-distancecommunicationofopticalfiber,isunderstudyasanopticalamplifier.
EccentricfiberThecoreofthestandardfiberissetinthecenterofthecladding,andthecross-sectionalshapeofthecoreandthecladdingisconcentric.However,duetodifferentuses,therearealsocaseswherethecoreposition,coreshape,andcladdingshapearemadeintodifferentstatesorthecladdingisperforatedtoformaspecial-shapedstructure.Comparedwithstandardopticalfibers,theseopticalfibersarecalledspecial-shapedopticalfibers.ExcentricCoreFiber(ExcentricCoreFiber),itisakindofspecial-shapedfiber.Thecoreissetoff-centerandclosetotheeccentricpositionoftheouterlineofthecladding.Sincethecoreisclosetothesurface,partofthelightfieldwillspreadoverthecladding(calledthisastheEvanescentWave).Therefore,whenasubstanceisattachedtothesurfaceoftheopticalfiber,thelightwavespropagatingintheopticalfiberduetotheopticalpropertiesofthesubstanceareaffected.Iftherefractiveindexoftheattachedsubstanceishigherthanthatoftheopticalfiber,thelightwavesradiateoutoftheopticalfiber.Iftherefractiveindexoftheattachedsubstanceislowerthantherefractiveindexoftheopticalfiber,thelightwavecannotradiateoutward,butitwillbelostduetotheabsorptionofthelightwavebythesubstance.Usingthisphenomenon,thepresenceorabsenceofattachedsubstancesandchangesinrefractiveindexcanbedetected.Eccentricfiber(ECF)ismainlyusedasanopticalfibersensorfordetectingsubstances.Combinedwiththeopticaltimedomainreflectometer(OTDR)testmethod,itcanalsobeusedasadistributionsensor.
Light-emittingopticalfiberUseopticalfibermadeoffluorescentmaterial.Itisapartofthefluorescencegeneratedwhenitisirradiatedbylightwavessuchasradiation,ultravioletrays,etc.,whichcanbetransmittedthroughtheopticalfiberbyclosingtheopticalfiber.LuminescentFiber(LuminescentFiber)canbeusedtodetectradiationandultravioletrays,aswellaswavelengthconversion,orasatemperaturesensor,chemicalsensor.ItisalsocalledScintillationFiberinthedetectionofradiation.Fromtheperspectiveoffluorescentmaterialsanddoping,plasticopticalfibersarebeingdeveloped.
Multi-coreopticalfiberTheusualopticalfiberiscomposedofacoreregionandacladdingregionsurroundingit.However,MultiCoreFiberhasmultiplecoresinacommoncladdingarea.Duetotheclosenessofthecorestoeachother,therearetwofunctions.Oneisthatthecorespacingislarge,thatis,thereisnoopticalcouplingstructure.Thiskindofopticalfibercanincreasetheintegrationdensityperunitareaofthetransmissionline.Inopticalcommunications,ribboncableswithmultiplecorescanbemade,whileinnon-communicationfields,asopticalfiberimagebundles,therearethousandsofcoresmade.Thesecondistomakethedistancebetweenthecoresclose,whichcanproducelightwavecoupling.Usingthisprinciple,adual-coresensororopticalcircuitdeviceisbeingdeveloped.
HollowFiberTheopticalfiberismadeintoahollowcoretoformacylindricalspace.TheopticalfiberusedforlighttransmissioniscalledHollowFiber.Hollowopticalfiberismainlyusedforenergytransmission,andcanbeusedforX-ray,ultravioletandfarinfraredlightenergytransmission.Therearetwotypesofhollowfiberstructures:oneistomakeglassintoacylindricalshape,andthecoreandcladdingprinciplesarethesameasthoseofthesteptype.Usethetotalreflectionoflightbetweentheairandtheglasstospread.Sincemostofthelightcanbetransmittedintheairwithoutloss,ithasthefunctionofspreadingacertaindistance.Thesecondistomakethereflectanceoftheinnersurfaceofthecylindercloseto1,toreducereflectionloss.Inordertoimprovethereflectivity,adielectricissetinthelamptoreducethelossintheworkingwavelengthrange.Forexample,thelossofawavelengthof10.6pmcanreachafewdB/m.
Themeaingof100mfiber
Theso-vocatur 100Mfiberrefersto the accessrateis100M,100Mrefersto100Mbps(megabitspersecundum),unitisbits,et Itisnotaunitof bytes forgeneralfilesizet, et deprimet. Byteisabyte, et bits arebinariis,1byte=8bits. Ibi etiam velocitas debet 100X1024/8.
Generallyspeaking,foradownloadspeedofabout250KB/sec,theADSLbandwidthneedsabout2M.Toreachthedownloadspeedof2MB/secdisplayedbythe360Internetspeedtester,thebandwidthneedstobe10Mto20M,onlyfiberbroadbandUserscanonlyreachit,becausetheupstreamanddownstreamofthefiberarebalanced.
Ad cognoscendum opus transmissionis velocitatem, oportet intelligere unitatem operis transmissionis celeritatem. Nos fere dicunt unitof 100 MandGigabit net operas esse in (bitrate, id est, bit/secundum, bit/s. sothefiberspeedof100Misequalto12.5MB/s(thatis,100Mbps/sdividedby8).Manypeoplealsounderstandtheunitofnetworkspeedasbytespersecond(Byte/s),soitfeelsliketheoperatorhasnotallocatedsufficientbandwidthtohim.Thiscanonlybeatheoreticalvalue,andpracticalapplicationswillbeaffectedbymanyfactorssuchaselectromagnetics,computers,servers,networkcongestion,etc.Generallyspeaking,itcanonlyreach70%to80%ofthetheoreticalvalue,andsomenetworkcardscanreach90%.