简介：Vertical-cavitysurface-emittinglasers(VCSELs)aretheidealopticalsourcesfordatacommunicationandsensing.Indatacommunication,largedataratescombinedwithexcellentenergyefficiencyandtemperaturestabilityhavebeenachievedbasedonadvanceddevicedesignandmodulationformats.VCSELsarealsopromisingsourcesforphotonicintegratedcircuitsduetotheirsmallfootprintandlowpowerconsumption.Also,VCSELsarecommonlyusedforawidevarietyofapplicationsintheconsumerelectronicsmarket.Theseapplicationsrangefromlasermicetothree-dimensional(3D)sensingandimaging,includingvarious3Dmovementdetections,suchasgesturerecognitionorfacerecognition.NovelVCSELtypeswillincludemetastructures,exhibitingadditionaluniqueproperties,oflargestimportancefornext-generationdatacommunication,sensing,andphotonicintegratedcircuits.

简介：Opticalcouplingbehaviorandassociatedeffectsintwo-dimensionalimplant-definedcoherentlycoupledverticalcavitysurface-emittinglaser(VCSEL)arraysarestudiedviabothexperimentsandtheoreticalcalculations.Experimentsshowthatopticalcouplingbetweenarrayelementscanenhancethearray’soutputpower.Additionally,opticalcouplingvialeakyopticalfieldscanprovideextraopticalgainforthearrayelements,whichcanthenreducethethresholdsoftheseelements.Elementscanevenbepumpedwithoutcurrentinjectiontoemitlightbyreceivingastrongleakyopticalfieldfromotherarrayelements.Opticalcouplingcanalsocauseunusualphenomena:thecentralelementsinlarge-areacoherentlycoupledVCSELarraysthatlasepriortotheouterelementswhenthearraysarebiased,ortheaverageinjectioncurrentrequiredforeachelementtolase,whichismuchlowerthanthethresholdforasingleVCSEL.Theoreticalcalculationsareperformedtoexplaintheexperimentalresults.

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简介：Wehavefabricatedatop-emittingorganiclight-emittingdeviceonsiliconsubstratewithhighyellowluminancebasedon5,6,11,12-tetraphenylnaphthacenesub-monolayer.Itconsistsofathinlayerofhighlyconductivesilverasthesemitransparentcathodeandsurfaced-modifiedAgastheanode.Thedeviceturnsonat3Vwiththeluminanceof8.4cd/m^2.Themaximumcurrentefficiencyis1.3cd/Aat6Vandtheluminancereaches14790cd/m^2at14V.Theperformanceofthedeviceisexcellentintop-emittingorganiclight-emittingdevicesaccordingtoourknowledge.

简介：Spurredonbytheinventionofthebluelight-emittingdiode(LED)aquarterofacenturyago,theLEDindustryhasadvanceddramaticallyandhasrevolutionizedthesignaling/signage,mobileandflatpaneldisplay,andmorerecently,generallightingmarkets.Indeed,LEDsnowout-surpassinperformanceallconventional(e.g.,incandescent,fluorescent,high-intensitydischarge)lightsourcesingeneralilluminationapplications.Thequestionarises:whatmoreistobedone?ThuscomesthethesisforthisspecialissueonLEDsandapplications.Fromthecontributedarticles,welearnthatLEDtechnologycontinuestoevolveandtransformitselfnotonlywithintheexistingapplicationsbutisalsopositioningforbrandnewapplicationstocome,bothofwhicharehighlightedhere.

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简介：Inthisarticlewedefineasurfacefiniteelementmethod(SFEM)forthenumericalsolutionofparabolicpartialdifferentialequationsonhypersurfacesFinR~(n+1).ThekeyideaisbasedontheapproximationofFΓbyapolyhedralsurfaceΓ_hconsistingofaunionofsimplices(trianglesforn=2,intervalsforn=1)withverticesonF.AfiniteelementspaceoffunctionsisthendefinedbytakingthecontinuousfunctionsonΓ_hwhicharelinearaffineoneachsimplexofthepolygonalsurface.WeusesurfacegradientstodefineweakformsofellipticoperatorsandnaturallygenerateweakformulationsofellipticandparabolicequationsonΓ.Ourfiniteelementmethodisappliedtoweakformsoftheequations.Thecomputationofthemassandelementstiffnessmatricesaresimpleandstraightforward.Wegiveanexampleoferrorboundsinthecaseofsemi-discretizationinspaceforafourthorderlinearproblem.Numericalexperimentsaredescribedforseverallinearandnonlinearpartialdifferentialequations.Inparticularthepowerofthemethodisdemonstratedbyemployingit,tosolvehighlynonlinearsecondandfourthorderproblemssuchassurfaceAllen-CahnandCahn-Hilliardequationsandsurfacelevelsetequationsforgeodesicmeancuryatureflow.

简介：Aminopropyl,ethylenediamine,ethenylandglycidoxygroupsfunctionalizednanoparticles,withaveragediametersrangingfrom4to6nmandcontaining1.17mmolofgroups/g,arereadilyobtainedfromnanodiamondsmodifiedwithsilanecouplingagent.Forthestudyofthesenanoparticles,TEM,IRS,XPS,andTGanalysismethodshavebeenused.

简介：Thetimeevolutionofoxygenplasmatreatedpolystyrene(PS)surfaceswasinvestigateduponstoringthemintheairundercontrolledhumidityconditions.Themethodsofwatercontactangle,X-rayphotoelectronspectroscopy(XPS),sumfrequencygeneration(SFG)vibrationalspectroscopy,andatomicforcemicroscopy(AFM)wereusedtoinferthesurfacepropertiesandstructure.ChemicalgroupscontainingoxygenwereformedonthePSsurfacewiththeplasmatreatment,demonstratedbywatercontactangleandXPS.Thesurfacepolaritydecayedmarkedlyontime,asassessedbysteadyincreaseinthewatercontactangleasafunctionofstoragetime,fromzerotoaround60°.Theobserveddecayisinterpretedasarisingfromsurfacerearrangementprocessestoburyingpolargroupsawayfromtheuppermostlayerofthesurfaces,whichisincontactwithair.Ontheotherhand,XPSresultsshowthatthechemicalcompositioninthefirst3nmsurfacelayerisunaffectedbythesurfaceaging,andthedepthprofileofoxygenisessentiallythesamewithtime.ApossiblechangeofPSsurfaceroughnesswasexaminedbyAFM,anditshowedthattheincreaseofwatercontactangleduringsurfaceagingcouldnotbeattributedtosurfaceroughness.Thus,itisconcludedthatsurfaceagingisattributabletosurfacereorganizationandthemotionofoxygencontaininggroupsisconfinedwithintheXPSprobingdepth.SFGspectroscopy,whichisintrinsicallyinterface-specific,wasusedtodetectthechemicalstructureofPSsurfaceatthemolecularlevelaftervariousagingtimes.Theresultsareinterpretedasfollows.DuringtheagingoftheplasmatreatedPSsurfaces,theoxygencontaininggroupsundergoreorientationprocessestowardthepolymerbulkand/orparalleltothesurface,whiletheCH2moietystandsuponthePSsurface.Ourresultsindicatethatthesurfaceconfigurationchangesdonotrequirelargelengthscalesegmentalmotionsormigrationofmacromolecules.Motionsthatareresponsibleforsurfaceconfigurationchangescoul

简介：Thisreviewfocusedontherecentreportsrelatedtothefunction,characterizationandmodificationofoxygen-containingsurfacegroupsofactivatedcarbon(AC).TheOxygen-containingsurfacegroupswerebrieflydescribed,andthemostfrequentlyusedtechniquesforcharacterizationoftheoxygen-containingsurfacegroupsonACswerealsobrieflystated.Adetaileddiscussionoftheeffectsoftheoxygen-containingsurfacegroupsontheadsorptivecapacityofACwasgiven.Therecentprogressesinmodificationoftheoxygen-containingsurfacegroupsofACwerealsoreviewed.

简介：Ahybridmodeofone-andtwo-surfacemultipactoronthegrooveddielectricsurfaceisstudiedindetailusingbothananalyticalapproachandtwo-dimensionalparticle-in-cell（2DPIC）simulations.WhenthegroovewidthLeE0/（4πmef2）,bothslopesmayhavethemultipactors.TheelectronsurfacedensityofthemultipactordischargehasasharpincreaseatthelengthL=eE0/（4πmef2）.

简介：Themechanismofcarriertransportinorganiclight-emittingdevicesisnumericallystudied,onthebasisoftrappedcharge-limitedconductionwithanexponentialtrapdistribution.Thespatialdistributionsoftheelectricalpotential,fieldandcarrierdensityintheorganiclayerarecalculatedandanalysed.Mostcarriersaredistributednearthetwoelectrodes,onlyafewofthemaredistributedovertheremainingpartoftheorgaiclayer,Thecarriersareaccumulatedneartheelectrodes,andtheremainingregionisalmostexhaustedofcarriers.Whenthecharacteristicenergyoftrapdistributionisgreaterthan0.3eV.itleadstoareductionofcurrentdensity.Inordertoimprovethedeviceefficiency,organicmaterialswithminortrapsandlowcharacteristicenergyshouldbechosen.Thediffusioncurrentisthedominantcomponentneartheinjectionelectrode.whereasthedriftcurrentdominatestheremainingregionoftheorganiclayer.

简介：Realizationofefficientyellow-light-emittingdiodes(LEDs)hasalwaysbeenachallengeinsolid-statelighting.Greatefforthasbeenmade,butonlyslightadvancementshaveoccurredinthepastfewdecades.AftercomprehensiveworkonInGaN-basedyellowLEDsonSisubstrate,wesuccessfullymadeabreakthroughandpushedthewall-plugefficiencyof565-nm-yellowLEDsto24.3%at20A∕cm~2and33.7%at3A∕cm~2.ThesuccessofyellowLEDscanbecreditedtotheimprovedmaterialqualityandreducedcompressivestrainofInGaNquantumwellsbyaprestrainedlayerandsubstrate,aswellasenhancedholeinjectionbya3DpnjunctionwithV-pits.

简介：Photoniccrystalslabsintegratedintoorganiclight-emittingdiodes(OLEDs)allowfortheextractionofwaveguidemodesandthusanincreaseinOLEDefficiency.WefabricatedlinearBragggratingswitha460-nmperiodonflexiblepolycarbonatesubstratesusingUVnanoimprintlithography.Ahybridorganic–inorganicnanoimprintresistisusedthatservesalsoasahighrefractiveindexlayer.OLEDscomposedofapoly(3,4-ethylenedioxythiophene)polystyrenesulfonate(PEDOT:PSS)polymeranode,anorganicemissionlayer[poly(p-phenylenevinylene)(PPV)-derivative'SuperYellow'],andametalcathode(LiF/Al)aredepositedontotheflexiblegratingsubstrates.TheeffectsofphotoniccrystalslabdeformationinaflexibleOLEDarestudiedintheoryandexperiment.Thesubstratedeformationismodeledusingthefinite-elementmethod.Theinfluenceofthechangeinthegratingperiodandthewaveguidethicknessunderbendingareinvestigated.Thechangeinthegratingperiodisfoundtobethedominanteffect.Atanemissionangleof20°achangeintheresonancewavelengthof1.2%ispredictedforastrainof1.3%perpendiculartothegratinggrooves.ThisvalueisverifiedexperimentallybyanalyzingelectroluminescenceandphotoluminescencepropertiesofthefabricatedgratingOLEDs.

简介：Theplasmonicnanogapantennaisanefficientradiatingorreceivingopticaldevice.Theresonancebehaviorofopticalantennasiscommonlyattributedtotheexcitationofalocalizedsurfaceplasmonresonance(LSPR),whichcanbetheoreticallydefinedasthequasi-normalmode(QNM).ToclarifythephysicaloriginoftheLSPR,webuildupananalyticalmodeloftheLSPRbyconsideringamultiplescatteringprocessofpropagativesurfaceplasmonpolaritons(SPPs)ontheantennaarms.ThemodelcancomprehensivelyreproducethecomplexeigenfrequencyandthefielddistributionofQNMsoftheantenna,unveilingthattheLSPRarisesfromaFabry–PerotresonanceofSPPs.Byfurtherapplyingthecomplexpoleexpansiontheoremofmeromorphicfunctions,thefieldoftheantennaunderilluminationbyanearbydipoleemittercanbeanalyticallyexpandedwithQNMs,whichwellpredictsthefrequencyresponseoftheenhancementfactorofradiation.ThepresentmodelestablishesexplicitrelationsbetweentheconceptsoftheLSPRandthepropagativeSPPandintegratestheadvantagesoftheFabry–PerotandQNMformalismsofnanogapantennas.

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简介：柱体hydrogel在几何学简单并且容易综合，广泛地因此被用来调查hydrogel的胀大/缩小的不稳定性，许多不稳定性模式在文学被积累。不过，这种唯一的配置的不稳定性模式形成的机制充分远离是被理解。我们使用了并且延长，并且执行了抑制柱体hydrogel的胀大导致稳定性的线性不安分析聚合物胶化的最近发达的非线性的理论进圆柱的坐标。我们导出压力和联系平衡方程的增长明确的表达。我们为不稳定性的发作获得了批评条件并且在hydrogel的稳定性图上在细节探查了各种各样的参数的效果。稳定性图的变化的物理意思也被解释。

简介：PolysiliconMicroelectromechanicalsystems(MEMS)arethesubjectofintensiveresearches.SurfacechemistryandtopographyofaMEMSteststructurefabricatedatSandiaNationalLaboratory,USA,werestudiedbymeansofscanningelectronmicroscopy(SEM),X-rayphotoelectronspectroscopy(XPS)andatomicforcemicroscopy(AFM).XPSC()andSi2,spectrafromthepolysilieoncomponents,siliconnitridesubstrateandareferencesiliconwaferwerecompared.Theresultsconfirmthepresenceofaself-assembledmonolayer(SAM)ontheMEMSsurface.Anisland-likemorphologywasfoundonbothpolysiliconandsiliconnitridesurfacesoftheMEMS.Theislandstaketheformofcaps,beingupto0.5μmindiameterand20nminheight.Itisconcludedthattheco-existenceofcolumnargrowthandequiaxedgrowthduringthelowpressurechemicalvapordeposition(LPCVD)oftheselayersleadstotheobservedmorphologyandtheislandsarecapstothecolumnarstructures.

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