简介：Acoherentcombinationofemissionpowerfromanarrayofcoupledsemiconductorlasersoperatingonthesamechipisoffundamentalandtechnologicalimportance.Ingeneral,thenonlinearcompetitionamongthearraysupermodescanentailincoherenceandspectralbroadening,leadingtoaspatiotemporallyunstableandmultimodeemissionpatternandthuspoorbeamquality.Here,byharnessingnotionsfromsupersymmetric(SUSY)quantummechanics,wereportthatthestrategiccouplingbetweenaclassIII-Vsemiconductormicroringlaserarraywithitsdissipativesuperpartnercanbeusedtolimitthenumberofsupermodesavailableforlaseractionstoone.Weintroduceanovelapproachbasedonsecond-orderSUSYtransformationinordertodrasticallysimplifythesuperpartnerarrayengineering.Comparedtoaconventionallaserarray,whichhasamultimodespectrum,aSUSYlaserarrayisobservedtobecapableofoperatinginasingle(transverse)supermode.EnhancementofthepeakoutputintensityoftheSUSYlaserarrayhasbeendemonstratedwithhighefficiencyandlowerlasingthreshold,comparedwithasinglelaserandaconventionallaserarray.Ourexperimentalfindingspavethewaytowardsbroad-areaandhigh-powerlightgenerationinascalableandstablefashion.

简介：Pitchisoneofthemostimportantauditoryperceptioncharacteristicsofsound;however,themechanismunderlyingthepitchperceptionofsoundisunclear.Althoughtheoreticalresearcheshavesuggestedthatperceptionofvirtualpitchisconnectedwithphysicsincochleaofinnerear,thereisnodirectexperimentalobservationofvirtualpitchprocessinginthecochlea.Bylaserinterferometry,weobserveshiftphenomenaofvirtualpitchinbasilarmembranevibrationofexsomatizedcochlea,whichisconsistentwithperceptualpitchshiftobservedinpsychoacousticexperiments.Thismeansthatthecomplexmechanicalvibrationofbasilarmembraneincochleaplaysanimportantroleinpitchinformationprocessingduringhearing.

简介：Highspatialfrequencylaserinducedperiodicsurfacestructures(HSFLs)onsiliconsubstratesareoftendevelopedonflatsurfacesatlowfluencesnearablationthresholdof0.1J/cm2,seldomonmicrostructuresormicrogroovesatrelativelyhigherfluencesabove1J/cm^2.ThisworkaimstoenrichthevarietyofHSFLs-containinghierarchicalmicrostructures,byfemtosecondlaser(pulseduration:457fs,wavelength:1045nm,andrepetitionrate:100kHz)inliquids(waterandacetone)atlaserfluenceof1.7J/cm^2.TheperiodofSi-HSFLsintherangeof110–200nmisindependentofthescanningspeeds(0.1,0.5,1and2mm/s),lineintervals(5,15and20μm)ofscanninglinesandscanningdirections(perpendicularorparalleltolightpolarizationdirection).ItisinterestinglyfoundthatbesidesnormalHSFLswhoseorientationsareperpendiculartothedirectionoflightpolarization,bothclockwiseoranticlockwiserandomlytiltedHSFLswithamaximaldeviationangleof50°ascomparedtothoseofnormalHSFLSsarefoundonthemicrostructureswithheightgradients.RamanspectraandSEMcharacterizationjointlyclarifythatsurfacemeltingandnanocapillarywavesplayimportantrolesintheformationofSi-HSFLs.ThefactthatnoHSFLsareproducedbylaserablationinairindicatesthatmoderatemeltingfacilitatedwithultrafastliquidcoolingisbeneficialfortheformationofHSFLsbyLALs.Onthebasisofourfindingsandpreviousreports,asynergisticformationmechanismforHSFLsathighfluencewasproposedanddiscussed,includingthermalmeltingwiththeconcomitanceofultrafastcoolinginliquids,transformationofthemoltenlayersintoripplesandnanotipsbysurfaceplasmonpolaritons(SPP)andsecond-harmonicgeneration(SHG),andmodulationofSi-HSFLsdirectionbybothnanocapillarywavesandthelocalizedelectricfieldcomingfromtheexcitedlargeSiparticles.

简介：Theultrafastfiberlaserhasattractedagreatdealofresearchinterestduetoitslowcost,highefficiency,andsimplemaintenance.Opticalpassivedevicesarevitalpartsofafiberlaser.Inordertoobtainafiberlaserwithhighquality,opticalpassivedeviceswithhighperformancearerequired.Here,wedemonstrateahighlyintegratedopticaldevicewiththecombinationofasaturableabsorber(SA),coupler,isolator,wavelengthdivisionmultiplexer,anderbium-dopedfiber.Thebuilt-inSAhasamodulationdepthof7%andcanwithstandhighpumppowerduetotheuniquestructureoftheproposeddevice.Theproposeddeviceisappliedtoanultracompactfiberlaser,whichgreatlysimplifiesthelaserstructureandreducesthesizeoftheproposedlaser.Thecentralwavelength,pulseduration,repetitionrate,andsignal-to-noiseratiooftheoutputsolitonare1560nm,1.06ps,25.8MHz,and50dB,respectively.Theproposeddevicehasgreatpotentialforapplicationinhigh-powerandhigh-frequencyfiberlasers.Theproposedultracompactfiberlaserhasimportantapplicationsinopticalcommunication,opticalsensing,opticalfrequencycombs,andmicromachining.

简介：Transparentbrittlematerialssuchasglassandsapphirearewidelyconcernedandappliedinconsumerelectronics,optoelectronicdevices,etc.duetotheirexcellentphysicalandchemicalstabilityandgoodtransparency.Growingresearchattentionhasbeenpaidtodevelopingnovelmethodsforhigh-precisionandhigh-qualitymachiningoftransparentbrittlematerialsinthepastfewdecades.Amongthevarioustechniques,lasermachininghasbeenprovedtobeaneffectiveandflexiblewaytoprocessallkindsoftransparentbrittlematerials.Inthisreview,aseriesoflasermachiningmethods,e.g.laserfullcutting,laserscribing,laserstealthdicing,laserfilament,laserinducedbacksidedryetching(LIBDE),andlaserinducedbacksidewetetching(LIBWE)aresummarized.Additionally,applicationsofthesetechniquesinmicromachining,drillingandcutting,andpatterningareintroducedindetail.Currentchallengesandfutureprospectsinthisfieldarealsodiscussed.

简介：AstablewavelengthoperationHo:YAGlaserdual-pumpedbytwoorthogonallypolarizedTm:YLFlasersisreported.Underthecwoperationmode,alaseroutputpowerof24Wismeasured.Thecorrespondingopticalopticalconversionefficiencyis44.75%andtheslopeefficiencyis50.12%.UndertheQ-switchedoperationmode,theoutputmaximumaveragepoweris22.8Watthere-frequencyof6kHz.Thecorrespondingoptical-opticalconversionefficiencyandslopeefficiencyare42.64%and48.01%,respectively.Theoutputcentralwavelengthis2090.73nm,thelinewidthis0.40nm,andthebeamqualityisM~2<1.6.Moreover,theshiftoftheoutputcentralwavelengthislessthan0.01nm,andthelinewidthshiftisalsolessthan0.01nm.

简介：Wereportboundstatesofsolitonsfromaharmonicmode-lockedfiberlaserbasedonasolution-processedgraphenesaturableabsorber.Stablesolitonpairs,26.2psapart,aregeneratedwith720fsduration.Bysimplyincreasingthepumppower,thelasercanalsogenerateharmonicmode-lockingwithharmonicsuptothe26thorder(409.6MHzrepetitionrate).Thisisasimple,low-cost,all-fiber,versatilemultifunctionultrafastlaserthatcouldbeusedformanyapplications.

简介：Weexperimentallydemonstratetwokindsofallfew-modefiber(FMF)ringlaserswithhigh-ordermode(HOM)oscillationinthelasercavity.Onekindisaswitchable-wavelengthall-FMFHOMlaserwithanoutputoftunableopticalvortexbeams(OVBs);theotherisaQ-switchedall-FMFHOMlaserwithanoutputofpulsedcylindricalvectorbeams(CVBs).Thelasersarecomposedofall-FMFcomponentsandfew-modeerbium-dopedfiber.ASagnacinterferometermadeofa3dBFMFcouplerfunctionsasthewavelengthselector,andswitchablemultiwavelengthtunableOVBsareexperimentallyrealized.Carbonnanotube-basedsaturableabsorbersandthenonlinearpolarizationrotationtechniqueareusedtoachieveQ-switchedCVBlasers.Thisisthefirstreport,toourknowledge,onthegenerationofswitchable-wavelengthandQ-switchedHOMbeamsinall-FMFlasercavities.

简介：Znbasedmetalshaveexhibitedpromisingprospectsasastructuralmaterialforbiodegradableapplications.PureZnporousscaffoldswereproducedbylaserpowderbedfusion(LPBF)basedondatafilesofdesigningandCTseanning.MassiveZnevaporationduringlasermeltinglargelyinfluencedtheformationqualityduringLPBFofZnmetal.Themetalvaporinprocessingchamberwasblownoffandsuctionedoutefficientlybyanoptimizedgascirculationsystem.Numericalanalysiswasusedtodesignandtestifytheperformanceofgasflow.Thesurfaceofscaffoldswascoveredwithnumerousparticlesindifferentsizes.Processingporesoccurredneartheoutlinecontourofstruts.Theaveragegrainsizeinwidthwas8.5μm,andthehardnesswas43.8HV.Chemicalpluselectrochemicalpolishingobtainedunifonnandsmoothsurfacewithoutprocessingpores,butthediameterofstrutsreducedto250μmfromthedesignvalue300μm.Thepoorsurfacequalityandprocessingporeswereresultedbythesplashingparticlesincludedspattersandpowdersduetotherecoilforceofevaporation,andthehorizontalmovementofliquidmetalduetooverheatingandwetting.TheinsufficientmeltingattheoutlinecontourcombinedwithgoodwettingofZnliquidmetalfurtherincreasedthesurfaceroughnessandprocessingpores.

简介：Laser-inducedbreakdownspectroscopy(LIBS)wasexaminedtodetectatracesubstanceadheredontoAlalloysforthesurfaceinspectionofmaterialstobeadhesivelybonded.AsanexampleofSicontamination,siliconeoilwasemployedandsprayedontosubstrateswithacontrolledsurfaceconcentration.LIBSmeasurementsemployingnanosecondUVpulses(λ=266nm)andanoff-axisemissioncollectionsystemwithdifferentdetectingheightswereperformed.Becausesurfacecontaminantsareinvolvedintheplasmaformedbylaserablationofthesubstrates,therelativecontributionofthesurfacecontaminantsandthesubstratestotheplasmaemissioncouldbechangeddependingontheconditionsforplasmaformation.Thelimitofdetection(LOD)wasevaluatedunderseveraldetectingconditionsforinvestigatingthefactorsthataffectedtheLOD.Asignificantfactorwasthestandarddeviationvaluesofsignalintensitiesobtainedforthecleansubstrates.Thisvaluevarieddependingonthemeasurementconditions.FortheAlalloy(A6061),thesmallestLODobtainedwas0.529μg·cm^-2.Furthermore,animprovedLOD(0.299μg·cm^-2)wasobtainedfortheAlalloywithalowerSicontent.

简介：Becauseoftheexcellentmechanicalpropertiesof34C「NiMo6steel,itiswidelyusedinhigh-valuecomponents.Manyconventionalapproachestostrengthening-steelstypicallyinvolvethelossofusefulductility.Inthisstudy,34CrNiMo6Steelhavinghighstrengthandductilityisproducedbylasersolidforming(LSF)w让haquenching-tempering(QT)treatment.TemperingofbainiteismainlybysolidphasetransformationinthepreviousLSFlayersduringtheLSFprocess.ThestablemicrostructureofLSFconsistsofferriteandfinecarbides.Themicrostructuretransferstotemperedsorbiteafterheat-treatment.ThetensilepropertiesoftheLSFsteelmeetthoseofthewroughtstandard.TheUTSandelongationofLSFsampleat858MPa,19.2%,respectively,aregreaterthanthoseofthewrought.TheQTtreatmentenhancedtheultimatetensilestrengthandyieldstrengthoftheLSFsample.Theultimatetensilestrength,yieldstrength,reductioninarea,andelongationoftheLSF+QTsampleat980MPa,916MPa,58.9%,and13.9%,respectively,aregreaterthanthoseofthewroughtstandard.TheyieldstrengthoftheLSF+QTsampleisapproximately1.27timesthatofthewrought.TheLSFsamplesfailedinaductilefracturemode,whiletheLSF+QTsamplesshowedmixed-modefailure.ThedefectshaveonlyasmalleffectonthetensilepropertiesowingtotheexcellentductilityoftheLSFsample.

简介：Accordingtothemultipleresearchesinthelastcoupleofyears,laser-inducedbreakdownspectroscopy(LIBS)hasshownagreatpotentialforrapidanalysisinsteelindustry.Nevertheless,theaccuracyandprecisionmaybelimitedbycomplexmatrixeffectandself-absorptioneffectofLIBSseriously.Anovelmultivariatecalibrationmethodbasedongeneticalgorithm-kernelextremelearningmachine(GA-KELM)isproposedforquantitativeanalysisofmultipleelements(Si,Mn,Cr,Ni,V,Ti,Cu,Mo)inforty-sevencertifiedsteelandironsamples.First,thestandardizedpeakintensitiesofselectedspectralinesareusedastheinputofmodel.Then,thegeneticalgorithmisadoptedtooptimizethemodelparametersduetoitsobviouscapabilityinfindingtheglobaloptimumsolution.Basedonthesetwostepsabove,thekernelmethodisintroducedtocreatekernelmatrixwhichisusedtoreplacethehiddenlayer’soutputmatrix.Finally,theleastsquareisappliedtocalculatethemodel’soutputweight.InordertoverifythepredictivecapabilityoftheGA-KELMmodel,theR-squarefactor(R2),Root-mean-squareErrorsofCalibration(RMSEC),Root-mean-squareErrorsofPrediction(RMSEP)ofGA-KELMmodelarecomparedwiththetraditionalPLSalgorithm,respectively.TheresultsconfirmthatGA-KELMcanreducetheinterferencefrommatrixeffectandself-absorptioneffectandissuitableformulti-elementscalibrationofLIBS.

简介：Wereportonadiode-end-pumpedhigh-powerandhigh-energyNd:YAGsingle-crystalfiberlaserat1834nm.Two808nmdiodesinjectingabout58WpumppowerintotheNd:YAGfiberhavegenerated3.28Wcontinuouswaveand1.66WCr:ZnSe-basedpassivelyQ-switchedlasers.Slopeefficiencieswithrespecttopumppowersare8.7%forthecontinuous-wavelaserand4.9%fortheQ-switchedlaser.Theextractedmaximumpulseenergyisabout266.9μJ,andthecorrespondingmaximumpulsepeakpoweris2.54kW.Theseperformancesgreatlysurpasspreviousresultsregardingthisspecificlaseremissionbecausethelasergainmediumintheformoffibercansignificantlymitigatethermallyinducedpowersaturationthankstoitssignificantlyreducedthermallensingeffect.Single-crystalfiberlasersshowgreatpotentialforhighaveragepower,pulseenergy,andpeakpower.

简介：Laser-inducedbreakdownspectroscopy(LIBS)hasattractedextensiveattentionasanewtechniqueforin-situmarineapplication.Inthiswork,theinfluenceofdeep-seahighpressureenvironmentonLIBSsignalswasinvestigatedbyusingacompactLIBS-seasystemdevelopedbyOceanUniversityofChinaforthein-situchemicalanalysisofseawater.TheresultsfromthefieldmeasurementsshowthattheliquidpressurehasasignificanteffectontheLIBSsignals.Higherpeakintensityandlargerlinebroadeningwereobtainedasthepressureincreases.BycomparingthevariationsofthetemperatureandsalinitywiththeLIBSsignals,aweakcorrelationbetweenthemcanbeobserved.Underhighpressureconditions,theoptimallaserenergywashigherthanthatinairenvironment.Whenthelaserenergyexceeded17mJ,theeffectoflaserenergyonthesignalintensityweakened.Thesignalintensitydecreasesgraduallyatlargerdelays.TheobtainedresultsverifiedthefeasibilityoftheLIBStechniqueforthedeep-seain-situdetection,andwehopethistechnologycancontributetosurveyingmoredeep-seaenvironmentssuchasthehydrothermalventregions.

简介：Asanimportantnon-ferrousmetalstructuralmaterialmostusedinindustryandproduction,aluminum(Al)alloyshowsitsgreatvalueinthenationaleconomyandindustrialmanufacturing.HowtoclassifyAlalloyrapidlyandaccuratelyisasignificant,popularandmeaningfultask.Classificationmethodsbasedonlaser-inducedbreakdownspectroscopy(LIBS)havebeenreportedinrecentyears.AlthoughLIBSisanadvanceddetectiontechnology,itisnecessarytocombineitwithsomealgorithmtoreachthegoalofrapidandaccurateclassification.Asanimportantmachinelearningmethod,therandomforest(RF)algorithmplaysagreatroleinpatternrecognitionandmaterialclassification.ThispaperintroducesarapidclassificationmethodofAlalloybasedonLIBSandtheRFalgorithm.TheresultsshowthatthebestaccuracythatcanbereachedusingthismethodtoclassifyAlalloysamplesis98.59%,theaverageofwhichis98.45%.ItalsorevealsthroughtherelationshiplawsthattheaccuracyvarieswiththenumberoftreesintheRFandthesizeofthetrainingsamplesetintheRF.Accordingtothelaws,researcherscanfindouttheoptimizedparametersintheRFalgorithminordertoachieve,asexpected,agoodresult.TheseresultsprovethatLIBSwiththeRFalgorithmcanexactlyclassifyAlalloyeffectively,preciselyandrapidlywithhighaccuracy,whichobviouslyhassignificantpracticalvalue.

简介：Electricallyresponsivephotoniccrystalsrepresentoneofthemostpromisingintelligentmaterialcandidatesfortechnologicalapplicationsinoptoelectronics.Inthisresearch,dye-dopedpolymer-stabilizedcholestericliquidcrystals(PSCLCs)withnegativedielectricanisotropywerefabricated,andmirrorlesslasingwithanelectricallytunablewavelengthwassuccessfullyachieved.Unlikeconventionalliquid-crystallasers,theproposedlaseraidedintuningtheemissionwavelengththroughcontrollingthereflectionbandwidthbasedongradientpitchdistribution.Theprincipaladvantageoftheelectricallycontrolleddye-dopedPSCLClaseristhattheelectricfieldisappliedparalleltothehelicalaxis,whichchangesthepitchgradientinsteadofrotatingthehelixaxis,thuskeepingtheheliconicalstructureintactduringlasing.Thebroadtuningrange(~110nm)ofPSCLClasers,coupledwiththeirstableemissionperformance,continuoustunability,andeasyfabrication,leadstoitsnumerouspotentialapplicationsinintelligentoptoelectronicdevices,suchassensing,medicine,anddisplay.

简介：Achievingnotonlyhighmechanicalstrengthsbutalsohighductilityisrecentlyestablishedusinganadditivemanufacturingtechniquecalledselectivelasermelting.Inthepresentstudy,stainlesssteel304Lfullydensesamplesweresuccessfullyprintedusingthe3Dsystems-ProX300printingmachine.TheductilityandtensileyieldstrengthwerealmosttwoandthreetimeshighercomparedtothoseofASTMcast'salloy.Honeycomblikenano-cellularstructurew让hdifferentorientationwasobservedinthefinegrains(-4μm)duetofastcoolingrate.Inadd让ion,theformationofmartensitephaseinrandomgrainsisalsoacontributortothestrengths.Furthermore,negativeresidualstressesinthebuildandhorizonraldirectionsweredetectedandassistedfurtherincreaseinthetensilestrength.Fractographyrevealedtheductilefeatureofplasticdeformationandthecrackopeningsatunmeltedparticlesorpores.

简介：AnoverlaycoatingmaterialwasdepositedonasinglecrystalsuperalloySRR99bylasercladding.Themicrostructureandoxidationbehaviorofthiscoatingwasinvestigatedthroughscanningelectronmicroscopy(SEM)andX-raydiffraction(XRD).Theresultsindicatedthatalthoughthecompositionofthecoatingwaschosenbasedontheγ'compositioninReneN5superalloy,theprimarysolidificationphaseofthiscoatingduringlasercladdingwasγ-Ni.Furthermore,underthelasercladdingcondition,fineparalleldendritesgrewepitaxiallyinthecoatingfromthesubstrate,indicatingthesinglecrystalstructureofthesubstratewasreproduced.WhenthesinglecrystalMCrAlYcoatingwasoxidizedat1000,bothB-AI2O3and(Y-Al2O3formedduringinitialoxidationprocess.Astheoxidationtimeproceeded,thepreseneeof0-Al2O3facilitatedtheformationofNiAl2O4spineloxide.Oncethespinelwasobserved,itflourishedandinducedsomeporosityinthescale.Whenthescalethicknessincreasedto6-7μm,largeareaspallationofthescalebegan.

简介：Wepresentanultrabroadband,high-speedwavelength-sweptsourcebasedonaself-modulatedfemtosecondoscillator.Photoniccrystalfiberwaspumpedbyamode-lockedYb:CaF2laser,resultinginastrongspectralbroadeningfrom485to1800nm.Thepumplasercavitycouldberealignedinordertoachievetotalmode-lockingofthelongitudinalandtransverseTEM00andTEM01electromagneticmodes.Thisledtospatialoscillationsoftheoutputbeam,whichinducedmodulationofthecouplingefficiencytothefiber.Duetothefactthatnonlinearspectralbroadeningwasintensitydependent,thismechanismintroducedwavelengthsweepingatthefiberoutput.Thesweepingratecouldbeadjustedbetween7and21.5MHzbychangingthegeometryofthepumpcavity.Bycontrollingtheratioofthetransversemodeamplitudes,wewereabletotunethesweepingbandwidth,eventuallycoveringboththe1300nmand1700nmbioimagingtransparencywindows.Whencomparedwithpreviouslydemonstratedwavelength-sweptsources,ourconceptoffersmuchbroadertunabilityandhigherspeed.Moreover,itdoesnotrequireanadditionalintensitymodulator.

简介：Oneofthetechnicalbottlenecksoftraditionallaser-inducedbreakdownspectroscopy(LIBS)isthedifficultyinquantitativedetectioncausedbythematrixeffect.Totroubleshootthisproblem,thispaperinvestigatedacombinationoftime-resolvedLIBSandconvolutionalneuralnetworks(CNNs)toimproveKdeterminationinsoil.Thetime-resolvedLIBScontainedtheinformationofbothwavelengthandtimedimension.Thespectraofwavelengthdimensionshowedthecharacteristicemissionlinesofelements,andthoseoftimedimensionpresentedtheplasmadecaytrend.Theone-dimensionaldataofLIBSintensityfromtheemissionlineat766.49nmwereextractedandcorrelatedwiththeKconcentration,showingapoorcorrelationofR^2c=0.0967,whichiscausedbythematrixeffectofheterogeneoussoil.Forthewavelengthdimension,thetwo-dimensionaldataoftraditionalintegratedLIBSwereextractedandanalyzedbyanartificialneuralnetwork(ANN),showingR^2v=0.6318andtherootmeansquareerrorofvalidation(RMSEV)=0.6234.Forthetimedimension,thetwo-dimensionaldataoftime-decayLIBSwereextractedandanalyzedbyANN,showingR^2v=0.7366andRMSEV=0.7855.Thesehigherdeterminationcoefficientsrevealthatboththenon-KemissionlinesofwavelengthdimensionandthespectraldecayoftimedimensioncouldassistinquantitativedetectionofK.However,duetolimitedcalibrationsamples,thetwo-dimensionalmodelspresentedover-fitting.Thethree-dimensionaldataoftime-resolvedLIBSwereanalyzedbyCNNs,whichextractedandintegratedtheinformationofboththewavelengthandtimedimension,showingtheR^2v=0.9968andRMSEV=0.0785.CNNanalysisoftime-resolvedLIBSiscapableofimprovingthedeterminationofKinsoil.