简介:Thepolarizationevolutionofvectorbeams(VBs)generatedbyq-platesisinvestigatedtheoreticallyandexperimentally.AnanalyticalmodelisdevelopedfortheVBcreatedbyageneralquarter-waveq-platebasedonvectordiffractiontheory.ItisfoundthatthepolarizationdistributionofVBsvarieswithpositionandthevalueq.Inparticular,fortheincidenceofcircularpolarization,theexitvectorvortexbeamhaspolarizationstatesthatcoverthewholesurfaceofthePoincarésphere,therebyconstitutingafullPoincarébeam.Fortheincidenceoflinearpolarization,theVBisnotcylindricalbutspecularlysymmetric,andexhibitsanazimuthalspinsplitting.Theseresultsareinsharpcontrastwiththosederivedbythecommonlyusedmodel,i.e.,regardingtheincidentlightasaplanewave.Byimplementingq-plateswithdielectricmetasurfaces,furtherexperimentsvalidatethetheoreticalresults.
简介:Anefficientmethodtomountacoupledsilicamicrosphereandtaperedfibersystemisproposedanddemonstratedexperimentally.Forthepurposeofoptomechanicalstudies,high-quality-factoroptical(Q_o~10~8)andmechanicalmodes(Q_m~0.87×10~4)aremaintainedafterthemountingprocess.Forthemountedmicrosphere,thecouplingsystemismorestableandcompactand,thus,isbeneficialforfuturestudiesandapplicationsbasedonoptomechanicalinteractions.Especially,thepackagedoptomechanicalsystem,whichistestedinavacuumchamber,pavesthewaytowardquantumoptomechanicsresearchincryostat.
简介:WithMoS2assaturableabsorber,passiveQ-switchingandQ-switchedmode-lockingoperationsofaTm-dopedcalciumlithiumniobiumgalliumgarnet(Tm:CLNGG)laserwereexperimentallydemonstrated.TheQ-switchedlaseremittedamaximumaverageoutputpowerof62mWandhighestpulseenergyof0.72μJ.Q-switchedmodelockingwasalsoobtainedintheexperiment.TheresearchresultswillopenupapplicationsofMoS2atthemid-infraredwavelength.
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简介:Weinvestigatethediffractionoftheguidedmodesofadielectricslabwaveguideonasimpleintegratedstructureconsistingofasingledielectricridgeonthesurfaceofthewaveguide.Numericalsimulationsbasedonaperiodicrigorouscoupled-waveanalysisdemonstratetheexistenceofsharpresonantfeaturesandboundstatesinthecontinuum(BICs)inthereflectanceandtransmittancespectraoccurringattheobliqueincidenceofatransverseelectric(TE)-polarizedguidedmodeontheridge.Usingtheeffectiveindexmethod,weexplaintheresonancesbytheexcitationofcross-polarizedmodesoftheridge.FormationoftheBICsareconfirmedusingatheoreticalmodelbasedoncoupled-wavetheory.ThemodelsuggeststhattheBICsoccurduetothecouplingofquasi-TEandquasi-transverse-magneticmodesofthestructure.SimpleanalyticalexpressionsfortheangleofincidenceandtheridgewidthpredictingthelocationoftheBICsareobtained.Theexistenceofhigh-QresonancesandBICsenablesusingtheconsideredintegratedstructureforsensing,transformationofopticalsignals,andenhancingnonlinearlight–matterinteractions.DuetotheLorentzianlineshapeoftheresonancesneartheBICs,thestructureisalsopromisingforfilteringapplications.
简介:Weexperimentallydemonstratehighopticalqualityfactorsilicamicrodiskresonatorsonasiliconchipwithlargewedgeanglesbyreactiveionetching.For2-μm-thickmicroresonators,wehaveachievedwedgeanglesof59°,63°,70°,and79°withopticalqualityfactorsof2.4×10~7,8.1×10~6,5.9×10~6,and7.4×10~6,respectively,from~80μmdiametermicroresonatorsinthe1550nmwavelengthband.Also,for1-μm-thickmicroresonators,wehaveobtainedanopticalqualityfactorof7.3×10~6withawedgeangleof74°.
简介:Wedemonstratethatferroferric-oxide(Fe3O4)nanoparticlesexhibitnonlinearsaturableabsorptionpropertyat1.55μm,andfabricatetwofilmysaturableabsorbersbyembeddingthenanoparticlesintoapolyvinylalcohol(PVA)filmorpolyimide(PI)filmseparately.IntheFe3O4-PVA(Fe3O4-PI)Q-switchedfiberlaser,thepulserepetitionrateincreasesfrom8.5kHz(5.5kHz)to28kHz(49kHz)andthepulsedurationdecreasesfrom23.5μs(47μs)to6μs(3.5μs)byvaryingthepumppowerfrom25mW(23mW)to150mW(650mW).ExperimentresultsindicatethatPI-basedsaturableabsorberscanaffordlargerpowersthanPVA-basedsaturableabsorbers,whichcanbeattributedtothehigherfusionpointofthePIfilm.TheFe3O4-PIsaturableabsorberexhibitsfeaturesofhighdamagethreshold,lowcost,andgoodflexibility,whichcouldbeappliedinfieldsofnear-infraredpulsegenerationandfrequencyconversions.