《新能源技术与材料》第18章Responsive Photonic Crystals.pptx

ResponsivePhotonicCrystals

2outlineIntroductionFormationofPhotonicCrystalsGeneralStrategiesToCreateResponsivePhotonicStructuresResponsivePhotonicCrystalsApplicationofResponsivePhotonicCrystalsSummaryandOutlook

3IntroductionPhotonicCrystals：具有光子带隙（PBG）的人造周期性电介质结构，所谓的光子带隙是指某一频率范围的波不能在此周期性结构中传播。晶体内部的原子是周期性有序排列的，正是这种周期势场的存在，使得运动的电子受到周期势场的布拉格散射，从而形成能带结构，带与带之间可能存在带隙。电子波的能量如果落在带隙中，就无法继续传播。在光子晶体中是由光的折射率指数的周期性变化产生了光带隙结构，从而由光带隙结构控制着光在光子晶体中的运动。

4Introduction不同折射率的材料交替排列，并且各位点间距离相等形成周期性结构，产生光子晶体带隙，对一定频率的光波产生能带效应，也就是只有某种频率的光才会在某种周期距离一定的光子晶体中被完全禁止传播。HengLi,JournalofMaterialsChemistry,DOI:10.1039/C0JM02554B

5FormationofPhotonicCrystalsThefabricationmethodscanberoughlyclassifiedintotwogroups:top-downandbottom-upapproaches.Thetop-downapproachesoftenusetraditionalmicrofabricationmethods,suchasphotolithographyandetchingtechniques,toproducemicrostructureswithdesiredshape,size,andorderfrombulkmaterials.Bottom-upapproachesgenerallyinvolvetheself-assemblyofpreformedbuildingblocksintoperiodicphotonicstructures.JianpingGe,AngewandteChemieInternationalEdition,DOI:10.1002/anie.200907091

6GeneralStrategiesTo

CreateResponsivePhotonicStructuresResponsivephotoniccrystalsarematerialswithphotonicband-gappropertiesthatcanbetunedbyexternalstimuli.Tocreatesuchmaterials,astimulus-responsemechanismneedstobecoupledwiththephotoniccrystalstructure.A3DcolloidalcrystaldiffractslightofaspecificwavelengthasdeterminedbyBragg’slaw.Underpracticalconditions,thecolloidalspheresareembeddedinmatrixmaterialssuchassolventsandpolymers,andbyconsideringtheeffectiveindexofthesystem,Bragg’slawcanbeapproximatelyexpressedasJianpingGe,AngewandteChemieInternationalEdition,DOI:10.1002/anie.200907091

7GeneralStrategiesTo

CreateResponsivePhotonicStructuresThelatticeconstantofthecrystals,includingtheinterparticledistancein3Dsystemsandlayert