lumerical bandstructure webinar有损耗的粒子链实例

算能带结构BandstructureCalculationsinFDTDLumericalSolutions,仿真设置Simulation计算(2Dtriangular有损耗的粒子链实例LossyparticlechainIntroduction>AboutOurOur FDTD3AboutPatentsandpublicationsgrowingat70%per0

FDTD 和专 情E.YablonovitchandT.J.Gmitter,"Photonicbandstructure:theface-centered-cubiccase,"J.Opt.Soc.Am.A7,1792-1800 OpticsExpress,Vol.16,Issue6,pp.4330-4336 yticalmethodforbandstructurecalculationofphotonicfibersfilledwithliquidOpticsExpress,Vol.16,Issue9,pp.6668-6674ne-waveexpansionmethodforcalculatingbandstructureofphotoniccrystalslabswithperfectlymatchedlayers：JOSAA,Vol.21,Issue9,pp.1769-1775(2004)FDTDMethodforBandStructureComputation：PhotonicSpringerSeriesinOpticalSciences,2009,Volume152/2009,163-Introduction:Why 找到结构的带 photonicband 获得Bloch模式分布mode Determinelossandgroupvelocityofphotoniccrystalwaveguide bandgapFDTD有限差分时域法FiniteDifference (FDTD) Averygeneraltechniquethatcandealwithmanytypes 子学器件Notjustforbandstructurecalculationsbutcansimulateotherdevicessuchaswaveguides,photonic cost SimulationSimulationChallenges的 器件结构Complexdevice 宽光谱 材料色散Material Material 有很多仿真，计算时间相对较长ManysimulationslongsimulationdevicesafterobtainingIntroductionGeneralmethod ysisgroup进行 的、结构能够支持的模式频率performsaFourier ysistodeterminefrequenciesofmodesthataresupportedbythestructureforacertainangleof 方向的能带UsetheparametersweeptooltomodifytheboundaryconditionsandsweepoverrangeofpropagationanglestogetthefinalplotbandfrequenciesversuspropagationSimulationmethodology-结构参数化Sourcesand 变换FourierFFTSummationofSweepoverkk计算一个仿真，获得这个获得最终结果Collecting以上结果均有现成的ScriptSimulationMethodology-对squarerectangular,BCC晶格，仅需仿真一个晶胞unitcell（位/元对非直角型结构如hexagonal,FCC，需仿真多个晶胞（因为FDTD物件库里面的光子晶体结构组可 Pre-madephotoniclatticestructuresareavailablefordownloadfromtheobjectSimulationMethodology-SimulationMethodology-SimulationMethodology-仿真区SimulationBloch边界条件boundary在结构有周期性的方向Directionswherestructureis需要指定BlochBandfrequenciesaredeterminedbysettingBlochvector,PML/PMLPML/PMLPSimulationSimulationMethodology-2D仿真，Kz=0（Kx，Ky变化EnsuresthateachunitcellwillbethesamewayXY2DXY晶格常数nmSimulationmethodology- Out- nebandstructure:3Dsimulationregionwithboundaryconditionsintheuniformstructure仍然是2D正方形结构（如上图）2Dperiodicsquarez-方向使用BlochboundariesBlochvectorinout-neSimulationMethodology-光源与监视器Sourcesand随机分布的偶极子Randomlypositionedcloudof（非矩形晶胞

ΔθphaseoffsetfromreferenceksimulationwaveΔrpositionoffsetfromreference使用多个随机放置的时间监视器收集所在地的时变信号SeveralrandomlypositionedtimemonitorscollectfieldsovertimeSimulationMethodology-Setup参数化Parameterize使用Bloch边界UseBlochboundaryconditionsforRandomcloudofdipolesRectangular仅需要一个晶胞OnlyneedtosimulateoneunitSimulatemorethanunit不同晶胞内的偶极子需要位相补偿MatchingdipolepositionsineachunitcellwithphaseoffsetSimulationMethodologyCalculationsStep FourierStep2:SummationofStep3:重复计算不同的KRepeatforallStep4:Collectsweepresults,findresonancesSimulationMethodology-FourierApplyapodizationtofilteroutstartandendApplieswindowingfunctionexcludetransient分析组设置切趾参数Apodizationparametersaresetin ysis 变换ApplyFouriertransformapodizedtimesignalinordertogetSimulationMethodology-Summationof 变换相加SumthetransformedtimesignalsfromeachfieldcomponentoftimeSummingoverseveralmonitorsensuresthatallresonantfrequenciesarefoundevenifonemonitorislocatedinanodeofaparticularmode ysisgroup可以在物件库分析组 Fouriertransformandsummationaredoneusingthebandstructure ysisgroupwhichisavailablefromtheObjectlibrarySimulationMethodology- ysistimeapodization计算光谱分布CalculatesGetsfieldfromeachtime根据预先设定的参数切趾Apodizestimesignalbasedon进 变换TakesFourierSumsresultsfromeach datasetcalled“spectrum”whichincludesthespectrumdatacorrespondingvectorofSimulationmethodology-重复其它的kRepeatforallspectrumforasingleBlochUsetheparametersweeptooltorunoverarangeofBlochvectorsandcollectthespectrumConcurrentcomputingparametersweeprequiremanysimulationsthemtomanydifferentworkstations每台电脑可以分布式并行计算，可以使用所有的核（如果需要）Eachworkstationcanrunindistributedcomputingmodeusingallcores倍！前提：有额外的计算引 Simulationmethodology-使用给定的文本程式Usingascriptfile,collecttheresultsfromtheparameter可以画出给定KDirectlyplotthespectrumforeachSimulationMethodology-Bandstructure计算总结Apodizetime 变换Fouriertransformapodizedtime求和Sumspectrafromeachmonitortogetspectrum扫描所需要的KRunparametersweepoverrangeofBloch搜集所有结果CollectsummedFouriertransformedtimefrom用文本程式画出能带图FindpeaksforeachktogetTriangular2DLatticeExample2unitMatchingphase指定偏振态Differentmodesexcitedbasedondipolecollectssweepresults,extractsandplotsTM TEAdvanced光源与监视器Sourceand 光源光谱Source Advanced光源与监视器Sourceand cesourcesand

instrongmodalfieldAdvancedApodization可以借 监视器检测时变信号UseamoviemonitortodeterminethetimeanddurationoftheAdvancedApodization比较低StrengthofsignalfrommodeofinterestmaybestrongestinthisparticularstretchoftimeAdvanceAdvanceboundaryconditionstoisolatemodesofAdvancedSource一般是超宽光谱Abroadbandsourcepulseisusedby可以指定 的波长/频率范围ModifythesourcefrequencyandbandwidthtooverlapwiththefrequencyofthebandssomoreenergyiscoupledintomodesofAdvanced小 valueifbandscanbeseenclearlyintheplotoffsvskthebanddiagramisAdvancedTipsFDTD/boundarysetbasedonsourceangleLossyParticleChainExample1Dchainofgoldspheresperiodicalongx-获得能带图GoalistoplotbandstructureofthelongitudinalmodeofthestructurewhichhasstrongfieldsintheregionbetweentheLossyParticleChain损耗原因SourcesofAbsorbing（到自由空间，无法谐振与损耗相关的问题ProblemsassociatedwithResonantfieldsdecayUsefulpartoftimesignalis Difficulttoextractresonant LossyParticleChainSetup cedalongthex-axisintheregionbetween使用对称边界Modeofinteresthassymmetryacrossy=0 nessosetsymmetryconditionsinyandz感 modeandmonitorrecordsstrongersignalfromthatmoderesultinginstrongerpeakscomparedtootherbandsandlessEqui-frequencyEqui-frequencycontourequifrequencyChallengesand SolutionsandbestFullvectorial3D