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简介：Basedonthesecond-ordermoments,thispaperderivesananalyticalexpressionoftheM2factoroffour-petalGaussianbeam.TheresultsshowthattheM2factorisonlydeterminedbythebeamordern.Thecorrespondingnumericalcalculationsarealsogiven.Asthebeamorderincreases,theaugmentofM2factorisdisciplinary.AstheexpressionofM2factorisexpressedinseriesformandbecomesmorecomplicated,anewconciseformulaofM2factorisalsopresentedbyusingcurvefittingofnumericalcalculations.When3≤n≤200,themaximumerrorrateoffittingformulawillnotexceed2.6%andtheaverageerrorrateis0.28%.Thisresearchishelpfultotheapplicationsoffour-petalGaussianbeam.

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简介：Amolybdenumdisulfide（MoS2）saturableabsorberwasfabricatedbythermallydecomposingtheammoniumthiomolybdate.ByusingtheMoS2absorber,acompactdiode-pumpedpassivelyQ-switchedTm:GdVO4laserhasbeendemonstrated.AstableQ-switchedlaserwithrepetitionratesfrom25.58to48.09kHzwasachieved.Maximumaverageoutputpowerwas100mWwiththeshortestpulsedurationof0.8μs.Maximumpulseenergyis2.08μJatcenterof1902nm.

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简介：Wereporteddiversesolitonoperationsinathulium/holmium-dopedfiberlaserbytakingadvantageofataperedfiber-basedtopologicalinsulator（TI）Bi2Te3saturableabsorber（SA）.TheSAhadanonsaturablelossof53.5%andamodulationdepthof9.8%.Stablefundamentallymode-lockedsolitonsat1909.5nmwithdistinctKellysidebandsontheoutputspectrum,apulserepetitionrateof21.5MHz,andameasuredpulsewidthof1.26pswereobservedinthework.Byincreasingthepumppower,bothbunchedsolitonswithsolitonnumberupto15andharmonicallymode-lockedsolitonswithharmonicorderupto10wereobtained.Toourknowledge,thisisthefirstreportofbothbunchedsolitonsandharmonicallymode-lockedsolitonsinafiberlaserat2μmregionincorporatedwithTIs.

简介：本文尝试以大葱（长葱白品种）为实验材料,探讨其作为观察叶绿体、线粒体材料的可行性.结果表明：大葱的葱叶可用于观察叶绿体,鳞茎的鳞片叶可用于线粒体观察,且具有实验材料供应充足、撕取表皮操作难度低、观察效果好等优点.因此大葱也是观察叶绿体和线粒体的理想材料.

简介：FifteennewabsorptionlinesareobservedwhenstudyingCO2absorptionspectroscopybywavelengthmodulation(WM)techniquewithadistributedfeedbacklaser.TheovertonespectraofCO2around1.31μmandthecorrespondingspectralparameters(i.e.positions,intensities,self-broadeningcoefficients)arepresented.Theintensityoftheweakestlinedetectedis2.25163×10^-27cm^-1/(molecule·cm^-2)atthepressureof5Tort,withacorrespondingabsorptionof3.88×10^-8.

简介：搭建了一套基于铥钬共掺光纤的激光放大系统，包含1个2μm增益开关主振荡器和一级铥钬共掺光纤放大器。获得了平均功率大于300mw的2txm脉冲输出，放大器平均功率增益达11dB，放大斜率效率达30％，这些性能指标与双包层掺铥光纤放大器相当。输出脉冲重频在40kHz时，最高脉冲能量为7．27μJ，脉宽88ns，对应的峰值功率为82．6W。放大过程中，激光光谱宽度小于0．3nm，边模抑制比大于35dB。

简介：RecentexperimentalresultsofHL-1MtokamakandprogressofHL-2Aprojectarepresented.Strongfishboneinstabilitywasobservedduringoff-axisECRH.ThisisfirstobservationofthefishboneinstabilitypurelydrivenbyenergeticelectronsproducedbyECRH.TheMBIwasfirstproposedanddemonstratedonHL-1M.RecentlynewresultsofMBIexperimentwereobtainedbyincreasingthepressureofgas.Astair-shapedensityincrementwasobtainedwithhigh-pressuremulti-pulseMBIjustlikethedensityevolutionbehaviorduringthemultipelletinjection.Itisshown

简介：Multilayerblackphosphorus（BP）nanoplateletsofdifferentthicknesseswerepreparedbytheliquidphaseexfoliationmethodanddepositedontoyttriumaluminumgarnetsubstratestoformsaturableabsorbers（SAs）.Thesewerecharacterizedwithrespecttotheirthickness-dependentsaturableabsorptionpropertiesat3μm.TheBP-SAswereemployedinapassivelyQ-switchedEr:Lu2O3laserat2.84μm.ByusingBPexfoliatedindifferentsolvents,stablepulsesasshortas359nsweregeneratedatanaverageoutputpowerofupto755mW.Therepetitionrateintheexperimentwas107kHz,correspondingtoapulseenergyof7.1μJ.TheseresultsprovethatBP-SAshaveagreatpotentialforopticalmodulationinthemid-infraredrange.

简介：WithMoS2assaturableabsorber,passiveQ-switchingandQ-switchedmode-lockingoperationsofaTm-dopedcalciumlithiumniobiumgalliumgarnet（Tm:CLNGG）laserwereexperimentallydemonstrated.TheQ-switchedlaseremittedamaximumaverageoutputpowerof62mWandhighestpulseenergyof0.72μJ.Q-switchedmodelockingwasalsoobtainedintheexperiment.TheresearchresultswillopenupapplicationsofMoS2atthemid-infraredwavelength.

简介：Byusingtheultrasound-assistedliquidphaseexfoliationmethod,Bi2Te3nanosheetsaresynthesizedanddepositedontoaquartzplatetoformakindofsaturableabsorber（SA）,inwhichnonlinearabsorptionpropertiesaround2μmareanalyzedwithahome-mademode-lockedlaser.Withtheas-preparedBi2Te3SAemployed,astablepassivelyQ-switchedall-solid-state2μmlaserissuccessfullyrealized.Q-switchedpulseswithamaximumaverageoutputpowerof2.03Waregeneratedunderanoutputcouplingof5%,correspondingtothemaximumsingle-pulseenergyof18.4μJandpeakpowerof23W.Thedeliveredshortestpulsedurationandmaximumrepetitionrateare620nsand118kHzunderanoutputcouplingof2%,respectively.ItisthefirstpresentationofsuchBi2Te3SAemployedinasolid-stateQ-switchedcrystallinelaserat2μm,tothebestofourknowledge.Incomparisonwithother2Dmaterialssuitableforpulsed2μmlasers,thesaturableabsorptionperformanceofBi2Te3SAisprovedtobepromisingingeneratinghighpowerandhigh-repetition-rate2μmlaserpulses.

简介：Inthispaper,wepresenttheluminescentpropertiesofTm3+∕Ho3+co-dopednewglass.Aseriesofsilicategermanateglasswaspreparedbytheconventionalmelt-quenchingmethod.IntheTm3+∕Ho3+co-dopedsilicategermanateglass,astrongemissionof2μmoriginatingfromtheHo3+:5I7→5I8transitioncanbeobservedunderconventional808nmpumping.Thecharacteristictemperatures,structure,andabsorptionspectrahavebeenmeasured.TheradiativepropertiesofHo3+inthepreparedglasswerecalculated.TheemissioncrosssectionofHo3+ionstransitioncanreach4.78×10-21cm2around2μm,andtheFWHMisashighas153nm.TheenergytransferefficiencybetweenHo3+andTm3+hasalargevalue（52%）,whichindicatestheTm3+∕Ho3+co-dopedsilicategermanateglassisasuitablecandidateforthe2μmlaser.Moreover,theenergytransfermechanismbetweenTm3+andHo3+ionswasinvestigated.

简介：Theequilibriumgeometries,relativestabilities,andelectronicpropertiesofMnAgm(M=Na,Li;n+m≤7)aswellaspureAgn,Nan,Lin(n≤7)clustersaresystematicallyinvestigatedbymeansofthedensityfunctionaltheory.Theoptimizedgeometriesrevealthatfor2≤n≤7,therearesignificantsimilaritiesingeometryamongpureAgn,Nan,andLinclusters,andthetransitionsfromplanartothree-dimensionalconfigurationsoccuratn=7,7,and6,respectively.Incontrast,thefirstthree-dimensional(3D)structuresareobservedatn+m=5forbothNanAgmandLinAgmclusters.Whenn+m≥5,astrikingfeatureisthatthetrigonalbipyramidbecomesthemainsubunitofLinAgm.Furthermore,dramaticodd-evenalternativebehavioursareobtainedinthefragmentationenergies,secondorderdifferenceenergies,highestoccupiedandlowestunoccupiedmolecularorbitalenergygaps,andchemicalhardnessforbothpureanddopedclusters.Theanalyticresultsexhibitthatclusterswithanevenelectronicconfiguration(2,4,6)possesstheweakestchemicalreactivityandmoreenhancedstability.

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简介：Sr原子的运动过程在He-Sr的亚稳亚稳的转变激光纵的搏动的分泌物被分析，一个简明前後一致的物理模型被开发。分泌物参数，主要粒子密度，电子温度，和放射激光的脉搏的时间的进化是数字地计算的。模型提供的结果同意有实验的井，和每激光脉搏的时间的行为被模拟结果成功地解释。[从作者抽象]

简介：Wereportonbroadlywavelength-tunablepassivemode-lockingwithhighpoweroperatingatthe2μmwaterabsorptionbandinaTm:CYAcrystallaser.Withasimplequartzplate,stablemode-lockingwavelengthscanbetunedfrom1874to1973nm,withatunablewavelengthrangeupto~100nmandmaximumoutputpowerupto1.35W.Thebandwidthisnarrowas~6GHz,correspondingtoahighcoherence.Toourknowledge,thisisthefirstdemonstrationofwavelength-tunablemode-lockingwithwatt-levelinthe2μmwaterabsorptionband.Thehightemporalcoherentlasercanbefurtherappliedinspectroscopy,theefficientexcitationofmolecules,sensing,andquantumoptics.