简介：Wemeasuretheelectromagneticdegreeoftemporalcoherenceandtheassociatedcoherencetimeforquasi-monochromaticunpolarizedlightbeamsemittedbyanLED,afilteredhalogenlamp,andamultimodeHe–Nelaser.ThemethodisbasedonobservingattheoutputofaMichelsoninterferometerthevisibilities(contrasts)oftheintensityandpolarization-statemodulationsexpressedintermsoftheStokesparameters.Theresultsareingoodagreementwiththosededuceddirectlyfromthesourcespectra.Themeasurementsarerepeatedafterpassingthebeamsthroughalinearpolarizersoastoelucidatetheroleofpolarizationinelectromagneticcoherence.Whilethepolarizervariestheequal-timedegreeofcoherenceconsistentlywiththetheoreticalpredictionsandalterstheinnerstructureofthecoherencematrix,thecoherencetimeremainsalmostunchangedwhenthelightvariesfromunpolarizedtopolarized.Theresultsareimportantintheareasofapplicationsdealingwithphysicalopticsandelectromagneticinterference.

简介：Dual-pumpedmicroring-resonator-basedopticalfrequencycombs(OFCs)andtheirtemporalcharacteristicsarenumericallyinvestigatedandexperimentallyexplored.ThecalculationresultsobtainedbysolvingthedrivenanddampednonlinearSchr?dingerequationindicatethatanultralowcoupledpumppowerisrequiredtoexcitetheprimarycombmodesthroughanon-degeneratefour-wave-mixing(FWM)processand,whenthepumppowerisboosted,boththecombmodeintensitiesandspectralbandwidthsincrease.Atlowpumppowers,thefieldintensityprofileexhibitsacosinevariationmannerwithfrequencyequaltotheseparationofthetwopumps,whilearollTuringpatternisformedresultingfromtheincreasedcombmodeintensitiesandspectralbandwidthsathighpumppowers.Meanwhile,wefoundthatthepowerdifferencebetweenthetwopumpfieldscanbetransferredtothenewlygeneratedcombmodes,whicharelocatedonbothsidesofthepumpmodes,throughacascadedFWMprocess.Experimentally,thedual-pumpedOFCswererealizedbycouplingtwoself-oscillatingpumpfieldsintoamicroringresonator.ThenumericallycalculatedcombspectrumisverifiedbygeneratinganOFCwith2.0THzmodespacingover160nmbandwidth.Inaddition,theformationofarollTuringpatternathighpumppowersisinferredfromthemeasuredautocorrelationtraceofa10freespectralrange(FSR)OFC.Theexperimentalobservationsaccordwellwiththenumericalpredictions.Duetotheirlargeandtunablemodespacing,robustness,andflexibility,theproposeddual-pumpedOFCscouldfindpotentialapplicationsinawiderangeoffields,includingarbitraryopticalwaveformgeneration,high-capacityopticalcommunications,andsignal-processingsystems.