简介:Adiode-end-pumpedelectro-optic(EO)Q-switchedNd:YVO4laseroperatingatrepetitionrateof10kpps(pulsespersecond)wasreported.AblockofLa3Ga5SiO14(LGS)singlecrystalwasusedasaQ-switchandthedriverwasametaloxidesemiconductorfieldeffecttransistor(MOS-FET)pulserofhighrepetitionrateandhighvoltage.Atcontinuouswave(CW)operation,theslopeefficiencyofthelaserwas46%,andmaximumoptical-to-opticalefficiencywas38.5%.Usinganoutputcouplerwithtransmissionof70%,a10-kppsQ-switchedpulsetrainwith0.4-mJmonopulseenergyand8.2-nspulsewidthwasachieved,theopticalconversionefficiencywasaround15%,andthebeamqualityM2factorwaslessthan1.2.
简介:MonovalentionsLi+,Na+,andK+,aschargecompensators,areintroducedintoCaYAl3O7:M(M=Eu3+,Ce3+)inthisletter.TheircrystalphasesandphotoluminescencepropertiesofdifferentalkalimetalionsdopedinCaYAl3O7areinvestigated.Inaddition,theinfluenceofchargecompensationionLi+whichhasamoreobviousroleinimprovingluminescenceintensityonCaYAl3O7:Eu3+phosphorisintentionallydiscussedindetailandapossiblemechanismofchargecompensationisgiven.Theenhancementofredemissioncenteredat618nmbelongingtoEu3+isachievedbyaddingalkalimetalionLi+under393-nmexcitation.
简介:Alowcost8×10-Gb/stransmissionsystemover1500kmonconventionalfiberusingchirpedfiberBragggrating(CFBG)asdispersioncompensatorisdemonstrated.Thebiterrorrate(BER)below10-10at1500kmisobtained.Thechannelspacingis0.8nmandtheopticalamplifierspacingis100km.Only16erbium-dopedfiberamplifiers(EDFAs)areused.
简介:Wereportonthecontinuous-wave(CW)andpassiveQ-switchingperformanceofaminiatureYb:Y3Ga5O12crystallaserendpumpedbya935-nmdiodelaser.AmaximumCWoutputpowerof12.03Wisproducedwithanoptical-to-opticalefficiencyof54.4%,whiletheslopeefficiencyis63%.InthepassivelyQ-switchedoperationachievedwithaCr4+:YAGsaturableabsorber,anaverageoutputpowerof2.12Wat1025.2nmisgeneratedwithaslopeefficiencyof46%atapulserepetitionrateof5.0kHz.Thepulse’senergy,duration,andpeakpowerare424μJ,2.3ns,and184.3kW,respectively.
简介:Weprovidethefirstdemonstrationofpureredemissioninthevisiblelightregionviathree-photonexcitationinmonodisperseNa_3ZrF_7:Ernanoparticles(NPs)byusingalaseroperatinginthetelecommunicationband.NPsof~22nmindiameteraresynthesizedat260°Cbythethermaldecompositionmethod.TheexperimentalresultsrevealthattheNa_3ZrF_7:ErNPsexhibitpureredemissioninthevisibleregionunder1480nmlaserexcitation,andtheemissionintensityissignificantlyinfluencedbytheEr~(3+)ionconcentration.Thedecaytimesofthe~4S_(3∕2)→~4F_(15∕2)and~4F_(9∕2)→~4F_(15∕2)transitionsoftheEr~(3+)ionsat540and655nm,respectively,arereducedbyincreasingtheEr~(3+)ionconcentrationintheNa_3ZrF_7:ErNPs.Thesuppressedemissionintensityresultfromthedefect-relatedquenchingeffect:whentrivalentEr~(3+)ionsreplactetravalentZr~(4+)ions,extraNationsandFvacanciesareformedtore-balancethechargeintheNa_3ZrF_7matrix.TheemissioncoloroftheNa_3ZrF_7:ErNPsisrelatedtothecrossrelaxationbetweenEr~(3+)ions.Theseresultsprovideanimportantsteptowardmoreeffectivebiologicalimagingandphotodynamictherapybyminimizingthescatteringoftheexcitationlightandincreasingthepenetrationdepth.
简介:在LD端面抽运的Nd:YVO4激光器中插入Cr^4+:YAG晶体,获得了稳定的1.06μm波长的高重复率被动调Q脉冲激光输出。实验研究了抽运功率、腔长、输出镜透过率对输出功率的影响,以及不同抽运功率下脉冲重复频率和脉冲宽度的变化,并对结果进行了理论分析。当腔长为8cm,抽运功率为27W时,得到重复率37.8kHz、平均功率3.5W的调Q脉冲序列;单个脉冲能量为93μJ、脉宽为24ns、峰值功率为3.9kW。
简介:WedesignaD-shapedfiberopticbiosensorbasedonthesurfaceplasmonresonance(SPR)ofametal-graphenelayerandsimulatethisSPRusingthefiniteelementmethod.Usingametal-graphenelayerasthesensingmaterial,surfaceplasmaresonanceissimulatedastherefractiveindexoftheexternalenvironmentrangesfrom1.33to1.36.Simulationresultsshowthatametal-graphenelayerattachedtotheD-shapedopticalfibercorecancouplewithlightunderaspecificpolarizationstateandexcitestrongplasmaoscillationsonthelayersurface.Calculatedtransmissioncoefficientsshowthattheresonancewavelengthobviouslymovestowardlongerwavelengthsastherefractiveindexofthetestmediumincreases,andasensitivityof5400nm/RIUisobtained.Becauseofitslargesurfacevolumeratioandgoodbiocompatibility,graphenemaybeutilizedinmanyapplicationsinthefieldofbiosensing.
简介:Anewscreen-spotimagingmethodbasedonopticalmeasurementisproposed,whichisapplicabletotheclose-rangemeasurementofaircraft'sthree-dimensional(3D)attitudeparameters.Lasertrackerisusedtofinishtheglobalcalibrationsofthehigh-speedcamerasandthefixedscreensontestsite,aswellastoestablishmedia-coordinate-framesamongvariouscoordinatesystems.Thelasercooperationobjectmountedontheaircraftsurfaceprojectslaserbeamsonthescreensandthehigh-speedcamerassyn-chronouslyrecordthelight-spots'positionchangingwithaircraftattitude.Therecordedimagesequencesareusedtocomputetheaircraftattitudeparameters.Basedonthematrixanalysis,theerrorsourcesofthemeasurementaccuracyareanalyzed,andthemaximumrelativeerrorofthismathematicalmodelisestimated.Theexperimentalresultshowsthatthismethodeffectivelymakesthechangeofaircraftpositiondistinguishable,andtheerrorofthismethodisnomorethan3′whiletherotationanglesofthreeaxesarewithinacertainrange.
简介:Anovelno-guidelightpentype3D-coordinatemeasurementsystemwiththreesetsofpositionsensitivedevices(PSDs)torealizeintersectionconvergeinagingisintroduced.Itiscalledasthelightpentypemeasurementsystem,becausethemeasuringheadisshapedasapenwithseverallightsourcesonit.Thestructuredesign,measurementprincipleandexperimentalresultsarepresented.Thetheoreticalanalysisandexperimentalresultsprovethatthissystemhasadvancedfeaturesofsimplestructure,highautomation,andhighaccuracy,andcanbeusedinthemeasurementfieldsofmechanicalmanufacture,robot,auto,aviationandmedicineeffectively.
简介:Measurementoflightdistributioninbiologicaltissuecontributestoselectingstrategyandoptimizingdoseforbiomedicalapplication.Inthisletter,aphotoacousticmethodcombinedwithMonteCarlosimulationwasusedtoestimatethethree-dimensionallightdistributioninbiologicaltissue.Thelightdistributionwasproducedbyacylindricaldiffuserwhichinterposedintotissues.Thelightprofilesobtainedbythemethodwerecomparedtothosedetectedbyphotodiodes.Theexperimentalresultsdemonstratethefeasibilityofthismethod.Theapproachcanplayasignificantroleforphoto-dosimetryinbiomedicalphototherapy.
简介:Higher-bandself-trappingandoscillation(rotation)ofnonlinearquadruplebeamsintwo-dimensional(2D)squarephotoniclatticesarenumericallydemonstrated.Underappropriateconditionsofnonlinearity,aquadruple-likebeamcanself-trapintolocalizedmodesthatresideinthesecondBraggreflectiongapthroughsingle-siteexcitation.Bychangingtheinitialorientationoftheincidentquadruplebeamrelatedtothelattices,periodicoscillationsofthelocalizedquadruplemodemaybeobtained.Thelocalizedquadruplestatebecomesarotatingdoublychargedopticalvortex(DCV)duringrotationandshouldundergocharge-flippingwhentherotatingdirectionisreversed.
简介:ACe3+tion-dopedα-NaYF4singlecrystalofhighqualityisgrownsuccessfullybyanimprovedfluxBridgmanmethodundertheconditionsoftakingthechemicalrawcompositionofNaF:KF:YF3:CeF3inthemolarratioof30∶18∶48∶4,wheretheKFisshowntobeaneffectiveassistantflux.Thexraydiffraction,absorptionspectra,excitationspectra,andemissionspectraoftheCe3+t-dopedα-NaYF4singlecrystalaremeasuredtoinvestigatethephaseandopticalpropertiesofthesinglecrystals.TheabsorptionspectrumoftheCe3+t:α-NaYF4showsastrongbandthatpeaksatthewavelengthof300nm.TheemissionspectrumoftheCe3+t:α-NaYF4emitsanintenseultraviolet(UV)bandatthewavelengthof332nmundertheexcitationof300nmlight.Twoseparatedluminousbandsof330and350nm,whichcorrespondtothetransitions5d→2F25∕2and5d→F7∕2,canbeobtainedbyGaussfitting.ThestrongemissionintensityattheUVbandandtheexcellentopticaltransmissionintherangeofUVwavelengthsindicatethatCe3+t:α-NaYF4singlecrystalscanbeconsideredasapromisingmaterialforUVlasers.