简介:Anall-fiberopticallaserpulsemulti-passstretcherusingachirpedfiberBragggrating(CFBG)isdemonstrated.Pulsesfroma1053-nmmode-lockedfiberseedoscillatorarestretchedbymultiplepassingthroughachirpedfibergratingsetinafiberregenerativeamplifierstructure.Westretchthepulsefrom16psto1.855nsafterittransmitssevenloopsinthestretcher.Themainfactorsthataffectthestretchingresultsarediscussed.
简介:ASchwarzschildmicroscopewithanumericalapertureof0.2andamagnificationof130ina100μmfieldofview(FOV)isdesignedandisworkingat13.5nm.Meanwhile,aCCDisusedasadetectorwithapixelsizeof13μm×13μmandimagingareaof13mm×13mm.Theimagingqualitywithtolerancesofsystemanderrorsofmirrorsareconsidered.Weobtainthatthebeston-axesobjectresolutioncanbeuptoabout200nm,theaveragevalueis230nm,andtheresolutionisabout360nmat80μmFOV.
简介:Micro-depositionofanaluminumfilmof500-nmthicknessonaquartzsubstratewasdemonstratedbylaser-inducedforwardtransfer(LIFT)usingafemtosecondlaserpulse.Withthehelpofatomicforcemicroscopy(AFM)andscanningelectronmicroscopy(SEM),thedependenceofthemorphologyofdepositedaluminumfilmontheirradiatedlaserpulseenergywasinvestigated.Asthelaserfluencewasslightlyabovethethresholdfluence,thehigherpressureofplasmaforthethickerfilmmadethefreesurfaceofsolidphaseburstout,whichresultedinthatnotonlythesolidmaterialwassputteredbutalsothedepositedfilmintheliquidstatewasmadeirregularly.
简介:Awavelength-sweptlaserisconstructedusingafreespaceexternalcavityconfigurationcoupledwithafiberbasedringcavityatthe850nmregion.Theexternalcavityfilteremploysagalvo-mirrorscannerwithadiffractiongratingforwavelengthselection.Thefilterisconnectedtoaringcavitythroughanopticalcirculator.Theringcavitycontainsabroadbandsemiconductoropticalamplifierwithahighopticaloutput.Theperformanceofthislaserisdemonstratedwithbroadbandwidthsandnarrowlinewidths.The3dBlinewidthandthebandwidthofthissourceare0.05nm(~20GHz)and48nm,respectively.Themaximumoutputpoweris26mWat160mAcurrent.
简介:InordertoimprovetheopticalpropertiesoftheⅢ-Ⅴlaserdiodes(LDs)bymeansofH_2Splasmapassiva-tiontechnology,H_2SplasmapassivationtreatmentisperformedontheGaAs(110)surface.Theoptimumpassivationconditionsobtainedare60-Wradiofrequency(RF)powerand20-minduration.Sothelasercavitysurfacesaretreatedundertheoptimumpassivationconditions.Consequently,comparedwithun-passivatedlaserswithonlyAR/HR-coatings,thecatastrophicopticaldamage(COD)thresholdvalueofthepassivatedlasersbyH_2Splasmatreatmentisincreasedby33%,whichisalmostthesameasthatof(NH_4)_2S_xtreatment.Andthelife-testexperimenthasdemonstratedthatthispassivationmethodismorestablethan(NH_4)_2S_xsolutionwet-passivatedtreatment.
简介:The810-nmInGaAlAs/AlGaAsdoublequantumwell(QW)semiconductorlaserswithasymmetricwaveg-uidestructures,grownbymolecularbeamepitaxy,showhighquantumefficiencyandhigh-powerconver-sionefficiencyatcontinuous-wave(CW)poweroutput.Thethresholdcurrentdensityandslopeefficiencyofthedeviceare180A/cm~2and1.3W/A,respectively.Theinternallossandtheinternalquantumefficiencyare1.7cm~(-1)and93%,respectively.The70%maximumpowerconversionefficiencyisachievedwithnarrowfar-fieldpatterns.
简介:Asuccessfulbeamcleanupofa5-mJ/200-μspulsedsolid-statelasersystemoperatingat532-nmwavelengthisdemonstrated.Inthisbeamcleanupsystem,awave-frontsensor-lessadaptiveoptics(AO)systemissetupwitha20-elementbimorphmirror(BM),ahigh-voltageamplifier,acharge-coupleddevicecamera,andacontrolsoftwareimplementingthestochasticparallelgradientdescent(SPGD)algorithm.Thebrightnessofthelaserfocalspotisimprovedbecausethewave-frontdistortionshavebeencompensated.Theperformanceofthissystemispresentedandtheexperimentalresultsareanalyzed.
简介:Themulti-photonionizationspectrumofNOinthewavelengthregionof575-680nmisobtainedwithanopticalparametergeneratorandamplifier(OPG/OPA)pumpedbyapicosecondNd:YAGlaserasradiationsource.ThebandedstructureofthespectrumindicatesthatNOmoleculeisionizedinresonantmannerandthepeaksofthespectrumareassignedtothetransitionofNOmoleculefromthegroundelectronicstatetoA2∑(v'=0,1,2,3),E2∑(v'=0,1,2),F2Δ(v'=0,1,2,3)andH2∑(v'=0,1,2)intermediateresonantones.ThemoleculeconstantsaboutNO(A2∑,E2∑,F2Δ,H2∑)statesarecalculatedfromthecenterwavelengthofthespectrum.ItisalsofoundthatowingtothespecialelectronconfigurationofNO,thismoleculedoesnotfollowthenormaltransitionselectionruleofthediatomicmoleculeduringthemulti-photonprocess.
简介:使用RF-PECVD法分别在基底温度为60℃、120℃和200℃的N型单晶锗表面制备了α-C:H膜,采用拉曼光谱、傅里叶变换红外吸收光谱和原子力显微镜等技术手段研究分析了α-C:H膜的价键组成及表面形貌,讨论了基底温度对α-C:H膜微结构及部分性能的影响。结果表明,在α-C:H膜沉积过程中,基底温度对膜层微观结构有较大影响,基底温度60℃时,膜层表面光滑、致密无石墨化现象。随着基底温度的升高,α-C:H膜中含H量和微晶石墨量逐渐增多,α-C:H膜层性能也逐步退化。
简介:Toobtainhighpower589-nmyellowlaser,aT-shapedthermal-insensitivecavityisdesigned.Theoptimalpowerratioof1064-and1319-nmbeamsisconsideredandthefundamentalspotsizedistributionfromtheoutputmirrortothetwolaserrodsarecalculatedandsimulated,respectively.Asaresult,a589-nmyellowlaserwiththeaverageoutputpowerof5.7Wisobtainedintheexperimentwhenthetotalpumpingpoweris695W.Theoptical-to-opticalconversionefficiencyfromthefundamentalwavestothesumfrequencygenerationisabout15.2%andthepulsewidthis150nsattherepetitionrateof18kHz.Theinstabilityoftheyellowlaserisalsomeasured,whichislessthan2%within3h.ThebeamqualityfactorsareM_x~2=4.96andM_v~2=5.08.
简介:Wedemonstrateadiode-pumpTm3+t-dopedall-fiberlaseroperatingat1908nmbasedonamasteroscillatorpoweramplifier(MOPA)configuration.Inourwork,152Woflaseroutputpowerisgeneratedbyatotalincidentpumppowerof434Wat790nm,correspondingtothetotalopticalefficiencyof35%.Thelaserwavelengthis1908.29nm.Tothebestofourknowledge,itisthehighestoutputpowerreachedaround1908nmwithsuchanarrowlinewidthof0.18nmbasedonaMOPAconfiguration.
简介:Wereportthefabricationofsubmicrometerpitsarray(SP-array)on6H-SiCsurfacebytheinterferenceoftwofemtosecondlaserbeams.FormationmechanismsandopticalabsorptionofSP-arrayarestudied.Therelativereflectivityandtransmissivityofwhitelightdecreaseto10%ofthevaluesofSiCcrystal,andtheopticalabsorptionisenhancedto97%.Therelativereflectivityandtransmissivityofincidentangleswithintherangeof20°-60°arekeptbelow25%.TheenhancementmechanismofopticalabsorptionoftheSP-arrayisalsodiscussed.
简介:Athree-dimensionalmodelofGaAs/A1GaAsquantumdoubleringsinthelateralstaticelectricfieldisinvestigatedtheoretically.Theeigenvalueproblemwiththeeffective-massapproximationissolvedbymeansofthefinite-elementmethod.Theenergylevelsandwavefunctionsofquantum-confinedelectronsandheavyholesareobtainedandshowanagreementwithourprevioustheoreticalandexperimentalstudies.ItisshownintheapproximationofneglectingtheCoulombattractionbetweentheelectronandheavyholethatarelativelylargeStarkshiftofexcitonemissionof4meVisattainablewithanappliedelectricfieldof0.7kV/cm.
简介:WecreateaGaNphotocathodebasedongradedAlxGa1-xNbufferlayerstoovercometheinfluenceofbuffer-emissionlayerinterfaceonthephotoemissionoftransmission-modeGaNphotocathodes.Agateshapedspectralresponsewitha260-nmstartingwavelengthanda375-nmcut-offwavelengthisobtained.Averagequantumefficiencyis15%andshortwavelengthresponsesarealmostequivalenttolongwavelengthones.Thefittedinterfacerecombinationvelocityis5×104cm/s,withnegligiblemagnitude,provingthatthedesignofthegradedbufferlayersisefficientinobtaininggoodinterfacequalitybetweenthebufferandtheemissionlayer.
简介:Asecondgenerationsolaradaptiveoptics(AO)systemisbuiltandinstalledatthe1-mNewVacuumSolarTelescope(NVST)oftheFuxianSolarObservatory(FSO)in2015.TheAOhigh-ordercorrectionsystemconsistsofa151-elementdeformablemirror(DM),acorrelatingShack–Hartmann(SH)wavefrontsensor(WFS)witha3500Hzframerate,andareal-timecontroller.ThesystemsawfirstlightonMar.16,2015.Thesimultaneoushigh-resolutionphotosphereandchromosphereimageswithAOareobtained.Theon-skyobservationalresultsshowthatthecontrastandresolutionoftheimagesareapparentlyimprovedafterthewavefrontcorrectionbyAO.
简介:SiO_2thinfilmscontainingSi_(1-x)Ge_xquantumdots(QDs)arepreparedbyionimplantationandannealingtreatment.Thephotoluminescence(PL)andmicrostructuralpropertiesofthinfilmsareinvestigated.ThesamplesexhibitstrongPLinthewavelengthrangeof400—470nmandrelativelyweakPLpeaksat730and780nmatroomtemperature.Blueshiftisfoundforthe400-nmPLpeak,andtheintensityincreasesinitiallyandthendecreaseswiththeincreaseofGe-dopingdose.Weproposethatthe400—470nmPLbandoriginatesfrommultipleluminescencecenters,andthe730-and780-nmPLpeaksareascribedtotheSi=OandGeOluminescencecenters.