Chapter 8_ Light emission and interactions in nanoscale environments

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1、Chapter8LightemissionandopticalinteractionsinnanoscaleenvironmentsThescopeofthischapteristodiscussopticalinteractionsbetweennanoscalesystemsandthepropertiesoftheemittedradiation.ThisisdifferenttoChapter??whereweconsideredthefocusingandconfinementoffreepropagatingradiation.Tolinkthetwoto

2、picsitisalsonecessarytounderstandhowfocusedlightinteractswithnanoscalematter.Thisisadifficulttasksinceitdependsontheparticularmaterialproperties,theshapeoftheinvestigatedobjectsandalsoonthestrengthofinteraction.Never-theless,thereareissuesthatcanbediscussedfromamoreorlessgeneralpointofv

3、iew.Attheheartofnano-opticsarelight-matterinteractionsonthenanometerscale.Opticalinteractionswithnanoscalematterareencounteredinvariousfieldsofre-search.Forexample,theactivityofproteinsandothermacromoleculesisfollowedbyopticaltechniques,opticallyexcitedsinglemoleculesareusedtoprobethei

4、rnano-environmentandopticalinteractionswithsemiconductornanostructures(quantumwells/wires/dots)areactivelyinvestigatedbecauseoftheirtechnologicalpromiseasnanocompositematerialsorquantumcoherentdevices.Furthermore,variousnano-metricstructuresareencounteredinnear-fieldopticsastinylightso

5、urces.Torigorouslyunderstandlight-matterinteractionsweneedtoinvokequantumelectrodynamics(QED).Therearemanytextbooksthatprovideagoodunderstand-ingofopticalinteractionswithatomsormoleculesandweexpeciallyrecommendthebooksinRefs.[1-3].Sincenanometerscalestructuresareoftentoocomplextobesol

6、vedrigorouslybyQEDweprefertosticktoclassicaltheoryandinvoketheresultsofQEDinaphenomenologicalway.Ofcourse,theresultsobtainedinthiswayhavetobevalidated,butaslongasthereisnoexperimentalcontradictionwearesaveto12CHAPTER8.LIGHTEMISSIONANDOPTICALINTERACTIONSusethisapproach.Aclassicaldescri

7、ptionisoftenmoreintuitivebecauseofitssimplerformalismbutalsobecauseitisclosertoourperception.8.1ThemultipoleexpansionInthissectionwewillconsideranarbitrary‘pieceofmatter’whichissmallcomparedtothewavelengthoflightandwhichwewilldesignatebyparticle.Althoughsmallcomparedtothewavelength,th

8、ispar