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1、RAPIDCOMMUNICATIONSPHYSICALREVIEWB68,161301~R!~2003!Nonlinearopticalabsorptionofsemiconductorquantumwires:PhotoexcitationdynamicaleffectsJustinoR.MadureiraInstitutodeFõÂsica,UniversidadeEstadualdeCampinas,CP6165,13083-970Campinas-SP,BrazilMarcosH.DeganiHa
2、rasDegani,AveFioravantePiovani1000,13250-000Itatiba-SP,BrazilMarceloZ.MaialleLiceuVivere,RuaDuquedeCaxiasNorte550,13635-000Pirassununga-SP,Brazil~Received4April2003;revisedmanuscriptreceived17July2003;published8October2003!Weinvestigatetheopticalabsorptio
3、nspectraofsemiconductorquantumwiresanditsdependenceontheopticalpumpingpower.Theabsorptioncoef®cientisobtainedsolvingthesemiconductorBlochequationsinthereal-spaceandtimedomains,includingcorrectionsduetoband-gaprenormalization,local®eld,andscreening.We®ndth
4、attheenergyshiftsinthespectraduetoincreasingphotoexcitationpowerhavedifferentbehaviorwhentreatingdynamicallythecarriercreationratherthanusingstationarycarrierdistributionatthermalequilibrium.Dealingwiththenonequilibriumdistributiondynamically,weareabletod
5、escribetheobservedconstancyofthepeakpositionofthefundamentaltransitionenergywiththeopticalpumpingpower.Thecompetingeffectsofthedynamicalband-gaprenormalizationandthelocal-®eldcorrectionleadstoanalmostcancellationofthered/blueshiftenergy.DOI:10.1103/PhysRe
6、vB.68.161301PACSnumber~s!:78.67.2n,85.35.Be,71.35.2yQuantumwirestructureshaveattractedmuchattentionsinceourmaininterestisonthecoherentexcitationdynam-duetotheirdistinctopticalandelectronicpropertieswhichicsthattakesplaceinfemtosecondscale.Wealsoconsiderha
7、vepotentialapplicationsinnoveloptoelectronicdevices.1,2thecaseofresonantexcitation,suchthatonlythelowestOnetypeofquantumwirethathasbeensuccessfullygrownconductionandthehighestvalencesubbandsofthequantumistheso-calledTwire,3wheretheelectronicstatesarelocal
8、-wireparticipate.Thespace-timeevolutionoftheinterbandizedattheintersectionoftwocrossingquantumwells.InopticalpolarizationP(z,t)andthenonequilibriumcarrier7,9,10,13tiltedTwire,forwhichthestemandarmwellsarenotor-popul
