lumerical bandstructure webinar有損耗的粒子鏈實例

算能帶結(jié)構(gòu)BandstructureCalculationsinFDTDLumericalSolutions,仿真設(shè)置Simulation計算(2Dtriangular有損耗的粒子鏈實例LossyparticlechainIntroduction>AboutOurOur FDTD3AboutPatentsandpublicationsgrowingat70%per0

FDTD 和專 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 找到結(jié)構(gòu)的帶 photonicband 獲得Bloch模式分布mode Determinelossandgroupvelocityofphotoniccrystalwaveguide bandgapFDTD有限差分時域法FiniteDifference (FDTD) Averygeneraltechniquethatcandealwithmanytypes 子學(xué)器件Notjustforbandstructurecalculationsbutcansimulateotherdevicessuchaswaveguides,photonic cost SimulationSimulationChallenges的 器件結(jié)構(gòu)Complexdevice 寬光譜 材料色散Material Material 有很多仿真，計算時間相對較長ManysimulationslongsimulationdevicesafterobtainingIntroductionGeneralmethod ysisgroup進行 的、結(jié)構(gòu)能夠支持的模式頻率performsaFourier ysistodeterminefrequenciesofmodesthataresupportedbythestructureforacertainangleof 方向的能帶UsetheparametersweeptooltomodifytheboundaryconditionsandsweepoverrangeofpropagationanglestogetthefinalplotbandfrequenciesversuspropagationSimulationmethodology-結(jié)構(gòu)參數(shù)化Sourcesand 變換FourierFFTSummationofSweepoverkk計算一個仿真，獲得這個獲得最終結(jié)果Collecting以上結(jié)果均有現(xiàn)成的ScriptSimulationMethodology-對squarerectangular,BCC晶格，僅需仿真一個晶胞unitcell（位/元對非直角型結(jié)構(gòu)如hexagonal,FCC，需仿真多個晶胞（因為FDTD物件庫里面的光子晶體結(jié)構(gòu)組可 Pre-madephotoniclatticestructuresareavailablefordownloadfromtheobjectSimulationMethodology-SimulationMethodology-SimulationMethodology-仿真區(qū)SimulationBloch邊界條件boundary在結(jié)構(gòu)有周期性的方向Directionswherestructureis需要指定BlochBandfrequenciesaredeterminedbysettingBlochvector,PML/PMLPML/PMLPSimulationSimulationMethodology-2D仿真，Kz=0（Kx，Ky變化EnsuresthateachunitcellwillbethesamewayXY2DXY晶格常數(shù)nmSimulationmethodology- Out- nebandstructure:3Dsimulationregionwithboundaryconditionsintheuniformstructure仍然是2D正方形結(jié)構(gòu)（如上圖）2Dperiodicsquarez-方向使用BlochboundariesBlochvectorinout-neSimulationMethodology-光源與監(jiān)視器Sourcesand隨機分布的偶極子Randomlypositionedcloudof（非矩形晶胞

ΔθphaseoffsetfromreferenceksimulationwaveΔrpositionoffsetfromreference使用多個隨機放置的時間監(jiān)視器收集所在地的時變信號SeveralrandomlypositionedtimemonitorscollectfieldsovertimeSimulationMethodology-Setup參數(shù)化Parameterize使用Bloch邊界UseBlochboundaryconditionsforRandomcloudofdipolesRectangular僅需要一個晶胞OnlyneedtosimulateoneunitSimulatemorethanunit不同晶胞內(nèi)的偶極子需要位相補償MatchingdipolepositionsineachunitcellwithphaseoffsetSimulationMethodologyCalculationsStep FourierStep2:SummationofStep3:重復(fù)計算不同的KRepeatforallStep4:Collectsweepresults,findresonancesSimulationMethodology-FourierApplyapodizationtofilteroutstartandendApplieswindowingfunctionexcludetransient分析組設(shè)置切趾參數(shù)Apodizationparametersaresetin ysis 變換ApplyFouriertransformapodizedtimesignalinordertogetSimulationMethodology-Summationof 變換相加SumthetransformedtimesignalsfromeachfieldcomponentoftimeSummingoverseveralmonitorsensuresthatallresonantfrequenciesarefoundevenifonemonitorislocatedinanodeofaparticularmode ysisgroup可以在物件庫分析組 Fouriertransformandsummationaredoneusingthebandstructure ysisgroupwhichisavailablefromtheObjectlibrarySimulationMethodology- ysistimeapodization計算光譜分布CalculatesGetsfieldfromeachtime根據(jù)預(yù)先設(shè)定的參數(shù)切趾Apodizestimesignalbasedon進 變換TakesFourierSumsresultsfromeach datasetcalled“spectrum”whichincludesthespectrumdatacorrespondingvectorofSimulationmethodology-重復(fù)其它的kRepeatforallspectrumforasingleBlochUsetheparametersweeptooltorunoverarangeofBlochvectorsandcollectthespectrumConcurrentcomputingparametersweeprequiremanysimulationsthemtomanydifferentworkstations每臺電腦可以分布式并行計算，可以使用所有的核（如果需要）Eachworkstationcanrunindistributedcomputingmodeusingallcores倍！前提：有額外的計算引 Simulationmethodology-使用給定的文本程式Usingascriptfile,collecttheresultsfromtheparameter可以畫出給定KDirectlyplotthespectrumforeachSimulationMethodology-Bandstructure計算總結(jié)Apodizetime 變換Fouriertransformapodizedtime求和Sumspectrafromeachmonitortogetspectrum掃描所需要的KRunparametersweepoverrangeofBloch搜集所有結(jié)果CollectsummedFouriertransformedtimefrom用文本程式畫出能帶圖FindpeaksforeachktogetTriangular2DLatticeExample2unitMatchingphase指定偏振態(tài)Differentmodesexcitedbasedondipolecollectssweepresults,extractsandplotsTM TEAdvanced光源與監(jiān)視器Sourceand 光源光譜Source Advanced光源與監(jiān)視器Sourceand cesourcesand

instrongmodalfieldAdvancedApodization可以借 監(jiān)視器檢測時變信號UseamoviemonitortodeterminethetimeanddurationoftheAdvancedApodization比較低StrengthofsignalfrommodeofinterestmaybestrongestinthisparticularstretchoftimeAdvanceAdvanceboundaryconditionstoisolatemodesofAdvancedSource一般是超寬光譜Abroadbandsourcepulseisusedby可以指定 的波長/頻率范圍ModifythesourcefrequencyandbandwidthtooverlapwiththefrequencyofthebandssomoreenergyiscoupledintomodesofAdvanced小 valueifbandscanbeseenclearlyintheplotoffsvskthebanddiagramisAdvancedTipsFDTD/boundarysetbasedonsourceangleLossyParticleChainExample1Dchainofgoldspheresperiodicalongx-獲得能帶圖GoalistoplotbandstructureofthelongitudinalmodeofthestructurewhichhasstrongfieldsintheregionbetweentheLossyParticleChain損耗原因SourcesofAbsorbing（到自由空間，無法諧振與損耗相關(guān)的問題ProblemsassociatedwithResonantfieldsdecayUsefulpartoftimesignalis Difficulttoextractresonant LossyParticleChainSetup cedalongthex-axisintheregionbetween使用對稱邊界Modeofinteresthassymmetryacrossy=0 nessosetsymmetryconditionsinyandz感 modeandmonitorrecordsstrongersignalfromthatmoderesultinginstrongerpeakscomparedtootherbandsandlessEqui-frequencyEqui-frequencycontourequifrequencyChallengesand SolutionsandbestFullvectorial3D