简介:Thebasicideaofthefiniteelementbeampropagationmethod(FE-BPM)isdescribed.Itisappliedtocalculatethefundamentalmodeofachannelplasmonicpolariton(CPP)waveguidetoconfirmitsvalidity.Boththefielddistributionandtheeffectiveindexofthefundamentalmodearegivenbythemethod.Theconvergencespeedshowstheadvantageandstabilityofthismethod.Thenaplasmonicwaveguidewithadielectricstripdepositedonametalsubstrateisinvestigated,andthegroupvelocityisnegativeforthefundamentalmodeofthiskindofwaveguide.Thenumericalresultshowsthatthepowerflowdirectionisreversetothatofphasevelocity.
简介:Theinfluenceofairturbulenceonthetransversewanderingofasinglefemtosecondlaserfilamentisstudiedbynumericalsimulation.Theresultsshowthattheaveragetransversedisplacementofthesinglefilament(δr}isproportionaltothesquarerootofturbulentstructureconstantandtherelationsbetweenandthepropagationdistancecanbefitbyapowerfunction.Inaddition,byusinganaxiconasafocusingoptics,thewanderingofasinglefilamentissuggestedtobestrongerthanthefree-propagationcase.
简介:Anewwavelengthbeamcombiningtechniqueforahigh-powerlaserdiodebarbyusingatemperaturegradientheatsinkhasbeenproposed.Thethermalcontrollingprincipleofthetemperatureheatsinkhasbeendiscussed.Ithasbeenprovedbyexperimentthatthelineartemperaturedistribution,whichgenerateslinearwavelengthspreadoftheoutputbeamsfromaLDbar,canbeobtainedbyintroducingatemperaturegradientheatsinkandtheoutputbeamscanbefocusedintoarelativesmallspotbyusingtheCzerny-Turnerbeamshapingsystem.
简介:Diffractiveopticsisanimportanttechniqueforbeamshapingwithhighlightefficiencyandstrongdiffractionpatternflexibility.Sincethediffractionangleislimitedbytheunitsizeofthediffractiveopticalelement(DOE),thesizeoftherequireddiffractionpatternisalwaysrathersmall.InthisLetter,refractive/diffractivehybridopticalelements(RDHOEs)consistingofaDOEandalensareusedtorealizebeamshapingforalargediffractionpattern.Thelens,asthecomponentoftheRDHOEs,cannotonlybeconcavebutalsoconvex,andthedoublesamplingFresneldiffractionalgorithmisdevelopedforthedesignofthesetwotypesofRDHOEs.Thesimulationandexperimentalresultsprovidesolidevidencetodemonstratetheproposedmethodwiththepurephasespatiallightmodulator.
简介:WeinvestigatethelateralshiftofaTM-polarizedlightbeamreflectedfromOttoconfigurationundergrazingincidence.Itisfoundthatthelateralshiftisstronglydependentonthethicknessoftheair-gaplayer.Byemployingthepole-nullrepresentation,wedemonstratethatthelateralshiftiscloselyrelatedtothenullofthereflectionfunction.ThenumericalsimulationsforaGaussianbeamareperformedtodemonstratethevalidityofourtheoreticalanalysis.
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:Aversatileandlow-costsingle-beamself-referencedphase-sensitivesurfaceplasmonresonance(SPR)sens-ingsystemwithultra-highresolutionperformanceispresented.Thesystemexhibitsaroot-mean-squarephasefluctuationof±0.0028°overaperiodof45min,i.e.aresolutionof±5.2×10~(-9)refractiveindexunits.Theenhancedperformancehasbeenachievedthroughtheincorporationofthreedesignelements:atruesingle-beamconfigurationenablingcompleteself-referencingsothatonlythephasechangeassociatedwithSPRgetsdetected,adifferentialmeasurementschemetoeliminatespurioussignalsnotrelatedtothesensorresponse,andtheeliminationofretardationdriftsbyincorporatingtemperaturestabilizationintheliquidcrystalphasemodulator.Ourdesignshouldbringthedetectionsensitivityofnon-labelingSPRbiosensingclosertothatachievablebyconventionalfluorescence-basedtechniques.
简介:Wereportthefabricationofsubmicrometerpitsarray(SP-array)on6H-SiCsurfacebytheinterferenceoftwofemtosecondlaserbeams.FormationmechanismsandopticalabsorptionofSP-arrayarestudied.Therelativereflectivityandtransmissivityofwhitelightdecreaseto10%ofthevaluesofSiCcrystal,andtheopticalabsorptionisenhancedto97%.Therelativereflectivityandtransmissivityofincidentangleswithintherangeof20°-60°arekeptbelow25%.TheenhancementmechanismofopticalabsorptionoftheSP-arrayisalsodiscussed.