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1、LETTERSPUBLISHEDONLINE:26JUNE2011
2、DOI:10.1038/NNANO.2011.99DetectingsinglevirusesandnanoparticlesusingwhisperinggallerymicrolasersLinaHe,S¸ahinKayaO¨zdemir,JiangangZhu,WoosungKimandLanYang*Thereisastrongdemandforportablesystemsthatcandetectmodesinaphotodetector,theoutputofwhichisaheterody
3、neandcharacterizeindividualpathogensandothernanoscalebeatnotewithbeatfrequencycorrespondingtothefrequencysplit-objectswithouttheuseoflabels,forapplicationsinhumanting22.Nanoparticleadsorptioneventscanthenberevealedinrealhealth,homelandsecurity,environmentalmonitoringanddiag-timebymonitori
4、ngthebeatnote.nostics1–6.However,mostnanoscaleobjectsofinteresthavelowIntheexperimentsweperformedinair,theWGMmicrolaserspolarizabilitiesduetotheirsmallsizeandlowrefractiveindexhadatoroid-shapedstructurefabricatedfromerbium-dopedcontrastwiththesurroundingmedium.Thisleadstoweaksilica(Er:SiO
5、)23,24.TheconcentrationofEr3þionsinthesilica21823light–matterinteractions,andthusmakesthelabel-freedetec-was5×10ionscm,whichensuredcontinuous-wave(c.w.)tionofsinglenanoparticlesverydifficult.Micro-andnano-laseroperation.Theresonatorswere20–40mmindiameter,with6photonicdeviceshaveemergedash
6、ighlysensitiveplatformsQfactorof6×10at1.46mm.Theexperimentalsetupisshownforsuchapplications,becausethecombinationofhighinFig.1a.Thefibre-tapercoupledmicrolaserwascontinuously3þqualityfactorQandsmallmodevolumeVleadstosignifi-pumpedbyalightsourceat1.46mmwithintheErabsorptioncantlyenhancedli
7、ght–matterinteractions7–15.Forexample,band.Laseremissioninthe1.55mmbandwasmonitoredbyaphoto-whisperinggallerymodemicroresonatorshavebeenusedtodiodeconnectedtoanoscilloscope.Datawerecollectedatanacqui-detectandcharacterizesingleinfluenzavirions10andpoly-sitionrateof10framespersecond,andfreq
8、uencycomponentsofthestyrenenanoparticleswitharadiusof30nm(ref.12)bylaserbeatnotewereextractedviafastFouriertransform(FFT).measuringinthetransmissionspectrumeithertheresonanceFigure1bdepictstheworkingprincipleofnanoparticledetection.shift10ormodesplitting12inducedbyt
