凝聚态光物理.ppt

文档介绍：()=c/v()Snell’slawabsorption~resonanceluminescence~spontaneousemissionelasticandInelasticscatteringnonlinear-(R):R=reflectedpower/incidentpowerTransmissionortransmissivity(T):T=transmittedpower/incidentpowerR+T=1Refractiveindex(n):Absorptioncoefficient()dI=-dz*I(z);Beer’slaw:isstrongfunctionoffrequencyLuminescenceTheatomjumpstoanexcitedstatebyabsorptionofaPhoton,thenrelaxestoanintermediatestate,beforere-ofthelightN:thenumberofscatteringcentres/V;S:scatteringcross-section;=NSRayleighscattering::onstantTherelationshipbetweentherealandimaginarypartsoftwocoefficients:Forweaklyabsorbingmedium,isverysmall,Thereflectivity(normalincidence):Inthetransparentregionofmaterial:isverysmall,and2arenegligible,onemayconsideronlytherealpartsofnand;Intheabsorptionregion,oneneedtoknowboththerealandimaginarypartsofnand.,ponent(approximatelyconstantn=)R=,henceT=(1-R)2=,,,(SiO2),allthecharacteristicfeaturescrystallineinsulators,thetransrangefromaround200nmtobeyond2000nm;Smallabsorptionandscatteringlosses;nchangesbylessthan1%overthewholevisiblespectralregion;monlyaddedt