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: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.
简介:TheCa_2SiO_4:Dy~(3+)phosphorwassynthesizedbythehightemperaturesolid-statereactionmethodinair.TheemissionspectrumofCa_2SiO_4:Dy~(3+)phosphorshowsseveralbandsat486,575,and665nmunderthe365-nmexcitation.TheeffectsofLi~+,Na~+,andK~+ontheemissionspectrumofCa_2SiO_4:Dy~(3+)phosphorwerestudied,TheresultsshowthattheemissionspectrumintensityisgreatlyinfluencedbyLi~+,Na~+,andK~+.Thechargecompensationconcentrationcorrespondingtothemaximumemissionintensityisdifferentwithdifferentchargecompensations.
简介:Enhanced2.7μmemissionisobtainedinEr3+/Tm3+andEr3+/Ho3+codopedZBYAglasses.Absorptionandemissionspectraaretestedtocharacterizethe2.7μmemissionpropertiesofEr3+/Tm3+andEr3+/Ho3+dopedZBYAglassesandareasonableenergytransfermechanismof2.7μmemissionbetweenEr3+andTm3+Ho3+)ionisproposed.CodopingofTm3+orHo3+significantlyreducesthelifetimeoftheEr3+:4I13/2levelduetotheenergytransferofEr3+:4I13/2→Tm3+:3F4orEr3+:4I13/2→Ho3+:5I7.Thus,the2.7μmemissionisstrengthenedandthe1.5μmemissionisdecreasedaccordinglyespeciallyintheEr3+/Tm3+sample.TheupconversioneffectsbetweentheEr3+/Tm3+andEr3+/Ho3+dopedZBYAglassesaredifferentattributetothedifferentenergytransferefficiencies.Bothofthetwocodopedsamplespossessnearlyequallargeemissioncrosssection(16.6×10-21cm-2)around2.7μm.TheresultsindicatethatthisEr3+/Tm3+orEr3+/Ho3+dopedZBYAglasshaspotentialapplicationsin2.7μmlaser.
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: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:Er~(3+)-dopedphosphor-telluriteglassforbroadbandshort-lengthEr~(3+)-dopedfiberamplifier(EDFA)isfabricatedandcharacterized.Thedifferentialvalue(△T)ofonsetcrystallinetemperature(T_x)andglasstransitiontemperature(T_g)is206°C.ThestimulatedemissioncrosssectionofEr~(a+)iscalculatedfromab-sorptionspectrumbyMcCumbertheoryandis0.87×10~(-20)cm~2at1532nm.Abroad1.5-μmfluorescencespectrumwith54-nmfull-widthathalfmaximum(FWHM)isdemonstrated.Especially,themaximumphononenergyofundopedphosphor-telluriteglassis1100cm~(-1),whichrestrictstheupconversionlumines-cence.Itispossibletopumpefficientlyat980nm.TheseresultsindicateEr~(3+)-dopedphosphor-telluriteglassissuitableforfabricatingbroadbandshort-lengthEDFA.
简介:Nitridatedβ-Ga_2O_3(100)substratewasinvestigatedasthesubstrateforGaNepitaxialgrowth.Theeffectsofnitridationtemperatureandsurfaceroughnessofβ-Ga_2O_3wafersontheformationofGaNwerestudied.Itwasfoundthatthemostoptimizednitridationtemperaturewas900°C,andhexagonalGaNwithpreferredorientationwasproducedonthewell-polishedwafer.Thenitridationmechanismwasalsodiscussed.
简介:ApassivelyQ-switchedNd3+:YAGlaserwithcornercubeistheoreticallyandexperimentallystudied.Weanalyzethepolarizationvariationincavityandsimulatethepeakpower,pulseenergyandpulsewidthchangedwiththerotationangleofcornercubenumerically.Anexperimentismadetoverifythetheoreticalresults.Withrotatingtheangleofcornercubeabouttheaxisthevariationrangeofpeakpoweris1.77MW(from10.36to8.59MW),andthatofpulseenergyis14.9mJ(from159.5to174.4mJ),thefluctuationofpulsewidthis2.95ns.Theexperimentalresultsagreewiththetheoreticalanalysistotheextentofvariationrules.Themostdynamictostaticenergyratioof62.5%isachieved.
简介:Diode-pumpedpassivelyQ-switchedNd:GdVO4/Cr4+:YAGlaserswithasimpleflat-flatcavityweredemonstrated.Themaximumaverageoutputpowerat1.06μmwas1.25W.Thehighestpeakpowerandpulseenergywere7.56kWand75μJ,respectively,withthepulserepetitionrateof11.1kHzandpulsewidthof10nsattheincidentpumppowerof8W.
简介:Er3+-dopedheavymetalborosilicateglasseswerepreparedusingconventionalmeltingandquenchingmethod.Theemissionspectraof4Ⅰ13/2→4Ⅰ15/2transitionwereobserveduponexcitationat974nmandthelifetimeof4Ⅰ13/2levelofEr3+wasmeasured.Basedonthesedata,thefluorescencepropertiesofEr3+areinvestigatedontheemissionandgaincharacteristicsatthe1.5μmbands.Inparticular,theeffectofrelativeheavymetalcontentonfluorescencepropertiesisdiscussed.
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:WhenfemtosecondlaserpulsesinterferewithchirpedfemtosecondlaserpulsesinAs2S3fiber,achirpedfibergratingisformed.Ananalyticalexpressionisgiventodescribethechirpedgrating,anditsBraggreflectivityiscalculated.BecauseofthehighphotosensitiveeffectofAs2S3material,thechirpedfibergratinghasawideBraggreflectivespectrumandhighreflectivitybychoosingproperparameters.Thisindicatesthatthechirpedfibergratingcanbeusedasastretcherinthefemtosecondchirpedpulseamplification(CPA)system.
简介:Measurementoflightdistributioninbiologicaltissuecontributestoselectingstrategyandoptimizingdoseforbiomedicalapplication.Inthisletter,aphotoacousticmethodcombinedwithMonteCarlosimulationwasusedtoestimatethethree-dimensionallightdistributioninbiologicaltissue.Thelightdistributionwasproducedbyacylindricaldiffuserwhichinterposedintotissues.Thelightprofilesobtainedbythemethodwerecomparedtothosedetectedbyphotodiodes.Theexperimentalresultsdemonstratethefeasibilityofthismethod.Theapproachcanplayasignificantroleforphoto-dosimetryinbiomedicalphototherapy.