Overview
Theapplicationrangeoffiberlasersisverywide,includinglaserfibercommunication,laserspaceremotecommunication,industrialshipbuilding,automobilemanufacturing,laserengraving,lasermarking,lasercutting,printingrollers,Metalandnon-metaldrilling/cutting/welding(brazing,quenching,claddinganddeepwelding),militaryandnationaldefensesecurity,medicalequipmentandequipment,large-scaleinfrastructure,asapumpsourceforotherlasers,etc.
Fiberlasersrefertolasersthatuserare-earth-dopedglassfibersasgainmedia.Fiberlaserscanbedevelopedonthebasisoffiberamplifiers.Undertheactionofthepumplight,itiseasytoincreasethepowerdensityinthefiber,causingthelaserenergylevelofthelaserworkingmaterialto"populatenumberinversion".Whenapositivefeedbackloop(formingaresonantcavity)isproperlyadded,thelaseroscillationoutputcanbeformed.
Structure
Thegenerationoflasersignalrequiresthreebasicconditions:populationinversion,opticalfeedbackandreachingthelaserthreshold.Therefore,thelaseriscomposedofworkingmaterial,pumpsourceandresonanceThecavityconsistsofthreeparts.Thebasicstructureofthefiberlaserisasfollows.Thegainfiberisthegainmediumthatgeneratesphotons;thepumplightisusedasexternalenergytomakethegainmediumtoachievepopulationinversion,thatis,thepumpsource;theopticalresonantcavityiscomposedoftwomirrors,Thefunctionistomakethephotonsgetfeedbackandbeamplifiedintheworkingmedium.Thepumpedlightentersthegainfiberandisabsorbed,whichinturnreversesthenumberofenergylevelparticlesinthegainmedium.Whenthegainintheresonantcavityishigherthantheloss,alaseroscillationwillbeformedbetweenthetwomirrors,resultinginalasersignaloutput..
Features
(1)Goodbeamquality.
Thewaveguidestructureofthefiberdeterminesthatthefiberlaseriseasytoobtainasingletransversemodeoutput,andisnotaffectedbyexternalfactors,andcanachievehigh-brightnesslaseroutput.
(2)Highefficiency.
Fiberlaserscanachievehighlight-to-lightconversionefficiencybyselectingsemiconductorlaserswithmatchingemissionwavelengthsanddopedrare-earthelementabsorptioncharacteristicsasthepumpsource.Forytterbium-dopedhigh-powerfiberlasers,915-nmor975-nmsemiconductorlasersaregenerallyselected,whichhavealongerfluorescencelifetimeandcaneffectivelystoreenergytoachievehigh-poweroperation.Theoverallelectro-opticalefficiencyofcommercialfiberlasersisashighas25%,whichisconducivetocostreduction,energysavingandenvironmentalprotection.
(3)Goodheatdissipationcharacteristics.
Fiberlaserusesaslenderrare-earth-dopedfiberasthelasergainmedium,anditssurfaceareatovolumeratioisverylarge.Itisabout1000timesthatofasolidbulklaser,whichhasanaturaladvantageintermsofheatdissipationcapability.Thereisnoneedforspecialcoolingoftheopticalfiberinlowandmediumpowerconditions,andwatercoolingforheatdissipationunderhighpowerconditionscanalsoeffectivelyavoidthedropinbeamqualityandefficiencycausedbythermaleffectsthatarecommoninsolid-statelasers.
(4)Compactstructureandhighreliability.
Becausethefiberlaserusesasmallandflexiblefiberasthelasergainmedium,itisbeneficialtocompressthevolumeandsavethecost.Thepumpsourceisalsoasemiconductorlaserthatissmallinsizeandeasytomodularize.Commercialproductscangenerallybeoutputwithpigtails,combinedwithfiber-baseddevicessuchasfiberBragggratings.Allfiberscanberealizedaslongasthesedevicesarefusedtoeachother.Ithashighdisturbanceimmunityandhighstability,whichcansavemaintenancetimeandcost.
Type
First,classifyaccordingtothetypeoffibermaterial
1.Crystalfiberlaser.Theworkingmaterialislasercrystalfiber,mainlyrubysinglecrystalfiberlaserandnd3+:YAGsinglecrystalfiberlaser.
2.Nonlinearopticalfiberlaser.TherearemainlystimulatedRamanscatteringfiberlasersandstimulatedBrillouinscatteringfiberlasers.
3.Rareearthdopedfiberlasers.Thematrixmaterialoftheopticalfiberisglass,andtheopticalfiberisdopedwithrareearthelementionstoactivateittomakeafiberlaser.
4.Plasticfiberlaser.Dopinglaserdyeintothecoreorcladdingoftheplasticopticalfibertomakeafiberlaser.
Second,accordingtothegainmediumclassification:
1.Crystalfiberlaser.Theworkingmaterialislasercrystalfiber,mainlyrubysinglecrystalfiberlaserandNd3+:YAGsinglecrystalfiberlaser.
2.Nonlinearopticalfiberlaser.TherearemainlystimulatedRamanscatteringfiberlasersandstimulatedBrillouinscatteringfiberlasers.
3.Rareearthdopedfiberlasers.Dopingrareearthelementionsintothefibertoactivateit(Nd3+,Er3+,Yb3+,Tm3+,etc.,thematrixcanbequartzglass,zirconiumfluorideglass,singlecrystal)tomakeafiberlaser.
4.Plasticfiberlaser.Dopinglaserdyeintothecoreorcladdingoftheplasticopticalfibertomakeafiberlaser.
Three,accordingtotheresonantcavitystructureclassification
DividedintoFPcavity,ringcavity,loopreflectorfiberresonatorand"8"shapedcavity,DBRfiberlaser,DFBfiberlaser,etc.
Four.Accordingtofiberstructureclassification
Dividedintosingle-cladfiberlaser,double-cladfiberlaser,photoniccrystalfiberlaser,specialfiberlaser.
Five.Classificationbyoutputlasercharacteristics
Dividedintocontinuousfiberlasersandpulsedfiberlasers,amongwhichpulsedfiberlaserscanbedividedaccordingtotheirpulseformingprinciplesItisaQ-switchedfiberlaser(pulsewidthisontheorderofns)andamode-lockedfiberlaser(pulsewidthisontheorderofpsorfs).
Advantages
Asarepresentativeofthethird-generationlasertechnology,fiberlasershavethefollowingadvantages:
(1)Glassopticalfiberhaslowmanufacturingcost,maturetechnologyandTheadvantagesofminiaturizationandintensivenessbroughtaboutbytheflexibilityoftheopticalfiber;
(2)Theglassfiberdoesnotrequirethestrictphasematchingofthecrystaltotheincidentpumplight,whichisduetotheglassmatrixStarkThenon-uniformbroadeningcausedbysplittingcausestheabsorptionbandtobewider;
(3)Glassmaterialhasaverylowvolume-to-arearatio,fastheatdissipationandlowloss,sotheconversionefficiencyishighandthelaserthresholdislow;
(4)Therearemanyoutputlaserwavelengths:thisisbecausetheenergylevelsofrareearthionsareveryrichandtherearemanykindsofrareearthions;
(5)Tunability:duetotheenergyofrareearthionsThegradewidthandthefluorescencespectrumoftheglassfiberarewider.
(6)Becausethereisnoopticallensintheresonantcavityoffiberlaser,ithastheadvantagesofadjustment-free,maintenance-freeandhighstability,whichisunmatchedbytraditionallasers.
(7)Thefiberexportmakesthelasercapableofvariousmulti-dimensionalandarbitraryspaceprocessingapplicationseasily,makingthedesignofthemechanicalsystemverysimple.
(8)Competentinharshworkingenvironment,withhightolerancetodust,shock,impact,humidityandtemperature.
(9)Thereisnoneedforthermoelectriccoolingandwatercooling,justsimpleaircooling.
(10)Highelectro-opticalefficiency:Thecomprehensiveelectro-opticalefficiencyisashighas20%,whichgreatlysavespowerconsumptionduringworkandsavesoperatingcosts.
(11)Thehigh-power,commercialfiberlaserissixkilowatts.
Applications
1.Markingapplications
Pulsefiberlasersareknownfortheirexcellentbeamquality,reliability,andthelongestMaintenance-freetime,thehighestoverallelectro-opticalconversionefficiency,pulserepetitionfrequency,thesmallestvolume,thesimplestandmostflexiblewaytousewithoutwatercooling,andthelowestoperatingcostmakeittheonlychoiceforhigh-speedandhigh-precisionlasermarking.
Asetoffiberlasermarkingsystemcanconsistofoneortwofiberlaserswithapowerof25W,oneortwoscanningheadstoguidelighttotheworkpieceandanindustrialcomputertocontrolthescanningheadcomposition.Thisdesignisupto4timesmoreefficientthansplittingthebeamwitha50Wlaserontotwoscanningheads.Themaximummarkingrangeofthesystemis175mm*295mm,thespotsizeis35um,andtheabsolutepositioningaccuracywithinthefullmarkingrangeis+/-100um.Thefocusspotcanbeassmallas15umataworkingdistanceof100um.
2.Applicationofmaterialprocessing
Thematerialprocessingoffiberlaserisbasedontheheattreatmentprocessinwhichthepartwherethematerialabsorbsthelaserenergyisheated.Laserlightenergywithawavelengthofabout1umiseasilyabsorbedbymetal,plasticandceramicmaterials.
3.Applicationofmaterialbending
Fiberlaserformingorbendingisatechniqueusedtochangethecurvatureofmetalplatesorhardceramics.Concentratedheatingandrapidself-coolingleadtoplasticdeformationinthelaserheatingarea,permanentlychangingthecurvatureofthetargetworkpiece.Researchhasfoundthatthemicrobendingwithlaserprocessinghasfarhigherprecisionthanothermethods.Atthesametime,itisanidealmethodinmicroelectronicsmanufacturing.
4.Applicationoflasercutting
Asthepoweroffiberlaserscontinuestorise,fiberlaserscanbeappliedonalargescaleinindustrialcutting.Forexample:usingafastchoppingcontinuousfiberlasertomicro-cutstainlesssteelarterialtubes.Duetoitshighbeamquality,thefiberlasercanobtainaverysmallfocusdiameterandtheresultingsmallslitwidthisrefreshingthestandardofthemedicaldeviceindustry.