简介:Rareattentionhasbeenpaidtothecomparisonbetweenamonomeranditscorrespondingpolymerintermsoftheoptoelectroniccharacteristics.Inthisarticle,amodelH-shapedmoleculeanditscorrespondingpolymer,bothofwhichexhibitedsimilarpropertiesincludingblueemissionandsolutionprocessing,weredesignedandsynthesized.Optoelectronicpropertiesandvariouskindsofstabilityfeatures,includingthethermostabilities,spectralstabilitiesandamplifiedspontaneousemissioncharacteristicofthemonomerandpolymerwereinvestigated.Ingeneral,thecorrespondingpolymerPHexhibitedsimilaroptoelectronicpropertiesbutdeterioratedstabilitiescomparedwithitsH-shapedmonomerH-1probablyowingtothesimilarchemicalstructurebutthewidermolecularweightdistributionandmetalcatalystresidue.Importantly,monomerH-1displayedacomparableASEthresholdvaluewithitspolymerPH,suggestingthatH-shapedfluorene-basedsmallmoleculesmaybemorepromisingopticalgainmediainsolidstateamplifersandlasers.
简介:Weexperimentallydemonstratedatypeoftunableandswitchableharmonich-shapedpulsegenerationinathulium-dopedfiber(TDF)laserpassivelymodelockedbyusinganultralongnonlinearopticalloopmirror.Thetotalcavitylengthwas~3.03km,thelongesteverbuiltforaTDFlasertoourbestknowledge,whichresultedinanultralargeanomalousdispersionover-200ps~2aroundtheemissionwavelength.Theproducedh-shapedpulsecanoperateeitherinafundamentalorinahigh-orderharmonicmode-locking(HML)statedependingonpumppowerandintra-cavitypolarizationstate(PS).Thepulseduration,nomatteroftheoperationstate,wastunablewithpumppower.However,pulsebreakingandself-organizingoccurred,resultinginhigh-orderHML,whenthepumppowerincreasedaboveathreshold.Atafixedpumppower,theorderofHMLwasswitchablefromonetoanotherbymanipulatingthePS.Switchingfromthe8thuptothe48thorderofHMLwasachievedwithafixedpumppowerof~4.15W.OurresultsrevealedthedetailedevolutionandswitchingcharacteristicsoftheHMLandindividualpulseenvelopewithrespecttoboththepumppowerandPS.Wehavealsodiscussedindetailthemechanismsofboththeh-shapedpulsegenerationandtheswitchingofitsHML.Thiscontributionwouldbehelpfulforfurtherin-depthstudyontheunderlyingdynamicsoflong-durationparticular-envelopepulseswithultralargeanomalousdispersionandultralongroundtriptime.
简介:WehavecomprehensivelyinvestigatedthefrustratedJ1-J2-J3Heisenbergmodelonasimplecubiclattice.Thismodelallowsthreeregimesofmagneticorder,viz.,(π;π;π),(0;π;π)and(0;0;π),denotedasAF1,AF2,andAF3,respectively.Theeffectsoftheinterplayofneighboringcouplingsonthemodelarestudiedintheentiretemperaturerange.Thezerotemperaturemagneticpropertiesofthismodelarediscussedutilizingthelinearspinwave(LSW)theory,nonlinearspinwave(NLSW)theory,andGreen’sfunction(GF)method.ThezerotemperaturephasediagramsevaluatedbytheLSWandNLSWmethodsareillustrated,andareobservedtoexhibitdifferentparameterboundaries.Incertainregionsandalongtheparameterboundaries,thepossiblephasetransformationsdrivenbytheparametersarediscussed.TheresultsobtainedusingtheLSW,NLSW,andGFmethodsarecomparedwiththoseobtainedusingtheseriesexpansion(SE)method,andareobservedtobeingoodagreementwhenthevalueofJ2isnotclosetotheparameterboundaries.ThegroundstateenergiesobtainedusingtheLSWandNLSWmethodsareclosetothatobtainedusingtheSEmethod.Atfinitetemperatures,onlytheGFmethodisemployedtoevaluatethemagneticproperties,andthecalculatedphasediagramisobservedtobeidenticaltotheclassicalphasediagram.Theresultsindicatethatattheparameterboundaries,atemperature-drivenfirst-orderphasetransitionbetweenAF1andAF2mayoccuralongtheboundaryline.AlongtheAF1-AF3andAF2-AF3boundarylines,AF3islessstablethanAF1andAF2.OurcalculatedcriticaltemperatureagreeswiththatobtainedusingMonteCarlosimulationsandpseudofermionfunctionalrenormalizationgroupscheme.
简介:Atemperature-inducedspinreorientationtransitionbetweenГ4(Gx,Ay,Fz)andГ2(Fx,Cy,Gz)hasbeenstudiedinthefamilyofEr1–xYxFeO3(x=0,0.25,0.5,0.75,1)singlecrystals.BydopingnonmagneticY3+,wetunedthespinreorientationtemperaturetolowtemperaturewithincreasingx.Moreover,thetypicalcompensationpointandspinfliptransitionofErFeO3alsodecreaseswithdoping,anddisappearsabovex=0.75.WealsoreporttheRietveldrefinementsandRamanspectroscopyofEr1–xYxFeO3,wheresomeRamanpeaksareshiftedtolowfrequencywithincreasingdoping.Ourresultsshedlightontheunderstandingoftheinteractionbetweentwomagneticsub-latticesofrareearth(R3+)andiron(Fe3+)ions,andwillalsocontributetothematerialsdesignandpotentialapplications.
简介:研究了考虑溶剂效应后2,1,3-苯并噻二唑衍生物中S原子被CH2—、O—和NH—取代引起的电子性质和光谱性质的变化,结果表明,与母体分子相比,O—取代引起的最高占据轨道能量(EHOMO)和最低空轨道能量(ELUMO)的变化很小,而CH2—和NH—取代引起的EHOMO和ELUMO的变化较明显,且CH2—和NH—取代后分子EHOMO的变化小于ELUMO的变化.CH2—取代导致最大吸收波长(λabs)和最大发射波长(λem)明显红移,而O—和NH—取代导致λabs和λem明显蓝移;而且取代后分子的吸收和发射光谱的振子强度都增大.
简介:WereportQ-switchedandmode-lockederbium-dopedall-fiberlasersusingternaryReS2(1-x)Se2xassaturableabsorbers(SAs).ThemodulationdepthandsaturableintensityofthefilmSAare1.8%and0.046MW∕cm2.InQ-switchedmechanismoutput,thepulsewascenteredat1531.1nmwithmaximumpulseenergyandminimumpulsewidthof28.29nJand1.07μs,respectively.Inmode-lockedoperation,thepulsewascenteredat1561.15nmwithpulsewidthof888fs,repetitionrateof2.95MHz,andmaximumpulseenergyof0.275nJ.Tothebestofourknowledge,thisisthefirstreportonthemode-lockedEr3+-dopedfiberlaserusingternarytransitionmetaldichalcogenides.Thisworksuggestsprospective2D-materialSAscanbewidelyusedinversatilefieldsduetotheirattractiveoptoelectronicandtunableenergybandgapproperties.