歡迎進(jìn)入FDTDSolutions的由四章內(nèi)容組成。第一章介紹FDTDSolutions的基本功能，以及器件建構(gòu)，程LUMERICAL的相應(yīng)網(wǎng)第三章環(huán)形諧振腔ThegoaloftheGettingStartedGuideistointroducetheFiniteDifferenceTime(FDTD)techniqueandexinhowmodelingisdonewiththesoftware.TheFDTDalgorithmisusefulfordesignandinvestigationinawidevarietyofapplicationsinvolvingthepropagationofelectromagneticradiationthroughcomplicatedmedia.Itisespeciallyusefulfordescribingradiation uponorpropagatingthroughstructureswithstrongscatteringordiffractiveproperties.Theavailablealternativecomputationalmethods-oftenrelyingonapproximatemodels-frequentlyprovideinaccurateresults.FDTDSolutionsisusefulfornumerousengineeringproblemsofcommercialinterestyopticalstorageLEDsmonpolaritonresonanceopticalwaveguidephotoniccrystalintegratedopticalopticalmicroParticleCalculationoftheSilvernanowireFDTDSolutionsisanaccurateandeasytouse,versatiledesigntoolcapableoftreatingthiswidevarietyofapplications.ThisintroductorychapteroftheGettingStartedGuideintroducesthegeneralFDTDmethodandprovidesaParticleCalculationoftheSilvernanowirecross-sectionsofaDeterminationoftheinsertionlossorreturnloss,andfrequencyresponseofwaveguide-basedcomponents.ManufacturingtolerancesarealsochanneldropfilterCavitiesandysisofresonantmodesandthecorrespondingdecayconstantsforcavitiesandPhotoniccrystalmicroTheFiniteDifferenceTime (FDTD)methodhas ethestate-of-the-artmethodforsolvingMaxwell’sequationsincomplexgeometries.Itisafullyvectorialmethodthatnaturallygivesbothtime ,andfrequency informationtotheuser,offeringuniqueinsightintoalltypesofproblemsandapplicationsinelectromagneticsandphotonics.Thetechniqueisdiscreteinbothspaceandtime.Theelectromagneticfieldsandstructuralmaterialsofinterestaredescribedonadiscretemeshmadeupofso-calledYeecells.Maxwell’sequationsaresolveddiscreyintime,wherethetimestepusedisrelatedtothemeshsizethroughthespeedoflight.ThistechniqueisanexactrepresentationofMaxwell’sequationsinthelimitthatthemeshcellsizegoestozero.Structurestobesimulatedcanhaveawidevarietyofelectromagneticmaterialproperties.Lightsourcesmaybeaddedtothesimulation.TheFDTDmethodisusedtocalculatehowtheEMfieldspropagatefromthesourcethroughthestructure.Subsequent tionresultsintheelectromagneticfieldpropagationintime.Typically,thesimulationisrununtilthereareessentiallynoelectromagneticfieldsleftinthesimulationregion. informationcanberecordedatanyspatialpoint(orgroupofpoints).Thisdatacanberecordedforthedurationofthesimulation,oritcanberecordedasaseriesof"snapshots"attimesspecifiedbytheuser. informationatanyspatialpoint(orgroupofpoints)maybeobtainedthroughtheFouriertransformofthetime informationatthatpoint.Thus,thefrequencydependenceofpowerflowandmodalprofilesmaybeobtainedoverawiderangeoffrequenciesfromasinglesimulation.Inaddition,resultsobtainedinthenearfieldusingtheFDTDtechniquemaybetransformedtothefarfield,inapplicationswherescatteringpatternsareimportant.MoreinformationabouttheFDTDmethod,includingreferences,canbefoundinthePhysicsoftheFDTDAlgorithmsectionofthereferenceguide.ThissectiondiscussesusefulfeaturesoftheFDTDSolutionsGraphicalUserInterfaceThegraphicaluserinterfacecontainsusefultoolsforeditingsimulations,atoolbarforaddingobjectstotheatoolbartoeditatoolbartorunanobjectstreetoshowtheobjectswhicharecurrentlyincludedintheascriptfileeditoranobjectawindowtosetupparametersweepsandInthedefaultconfigurationsomeoftheWindowsarehidden.Toopenhiddenwindows,clicktherightmousebuttonanywhereonthemaintitlebarorthetoolbartogetthepopupwindowshowninthescreenshotbelow.Thevisiblewindows/toolbarshaveacheckmarknexttotheirname;thehiddenonesdonothavecheckmarks.AsecondwaytoobtainthepopupwindowistogotothemaintitletoolbarandselectVIEW->WINDOWS.FormoreinformationaboutthetoolbarsandwindowsseetheLayouteditorsectionofthereferenceguide.AddObjectstotheTheGraphicalUserinterfacecontainsbuttonstoaddobjectstothesimulation.Clickonthearrownexttotheimagetogetapulldown whichshowsalltheavailableoptionsinagroup.ThescreenshotbelowshowswhathappenswhenweclickonthearrownexttotheCOMPONENTSbutton.NotethatthepictureonthebuttonisthesameastheMORECHOICESoptioninthelist.Ifweclickonthebuttonitself(insteadofthearrow)wewillgodirectlytotheMORECHOICESsectionoftheobjectlibrary.AlsonoticethatthepicturefortheCOMPONENTSbuttonwillchangedependingonwhatthelastcomponentthatwasaddedtothesimulationwas.Finally,theZOOMEXTENTbuttoninthetoolbarwillresizetheviewportstofitalltheobjectscurrentlyincludedinthesimulation.EditToeditanobject,selecttheobjectandpressEonthekeyboardorpresstheEDITonthetoolbar.Theeasiestwaytoselectanobjectistoclickonthenameoftheobjectintheobjectstree.However,objectscanalsobeselectedbyclickingonthegraphicaldepictionofthemwhentheSELECTbuttonispressed.FormoreinformationseetheLayouteditorsectionofthereferenceguide.WhenweeditobjectsinFDTD,wegetaneditwindow.Theeditwindowshaveunitsthesettings;intheGEOMETRYtab,thex,yandzlocationwillbeinμmbydefault.unitscanbechangedtonmifwechooseSETTINGS->LENGTHunitsinthemain Fieldsintheeditwindowsactlikecalculators,sothatequationscanbeenteredinthefields.Seetheyspanfieldbelowforanexample.Startanew2D/3DBydefaultFDTDSolutionsopenswithablank3Dsimulation.InthefollowingGettingStartedExamples,weoftenbeginwitha2Dsimulation,whichcanbeobtainedasshowninthescreenshotbelow.Thissectiondiscussesimportantcheckswhichshouldbemadebeforerunningasimulation(memoryrequirements,materialfits)andgiveslinkstomoreinformationaboutrunningsimulationsandparametersweepsoroptimizations.Tocheckthememoryrequirements,presstheCHECKbuttonIfthisisnotcurrenticon,youcanfinditbypressingthearrow.Notethatthememoryreportindicatestheamountofmemoryusedbyeachobjectinthesimulationprojectaswellasthetotalmemoryrequirements.Thisallowsforjudiciouschoiceofmonitorpropertiesinlargeandextensivesimulations.TheCHECKbuttonalsocontainsamaterialexploreroption.ManyofmaterialsusedinFDTDSimulationscomefromexperimentaldata(seethematerialssectionoftheReferenceGuideforreferencesforthematerialdataanddescriptionsoftheFDTDmaterialmodels).Beforerunningasimulation,FDTDSolutionsautomaticallygeneratesamulti-coefficientmodelfittothematerialdatainthewavelengthrangeforthesource.Itisagoodideatocheckandoptimizethematerialfitbeforerunningasimulation.SetuptheresourceconfigurationBeforerunninganysimulations,theresourceoptionsmustbesetup.TheseoptionsbeaccessedbypressingtheResourcesbutton.Inmostcases,thesettingsshouldbefine.The'numberofprocesses'istypicallysettothenumberofcoresinyourcomputer.RunYoucanrunsimulationsbypressingtheRUNbuttononthemailtoolbar.Formoredetails,suchashowtorunmultiplesimulationsindistributedmode,pleaseseetheRunSimulationssectionintheonlineUserGuide,ortheRunningsimulationsand sectionoftheReferenceGuide.RunparametersweepsandFDTDSolutionsalsohasabuiltinparametersweepandoptimizationwindow.Thiswindowcanbeseenatthetopofthepage,andcanbeopenedusingtheinstructionsintheGraphicalUserInterfacediscussionjustpriortothistopic.OptimizationWindowincludesbuttonstoaddaparametersweepandaddanoptimization.Parametersweepsandoptimizationscanincludemultipleparameters,orbenested.Eachoptimizationorsweepcanberunbypressingtheright-mostbutton.Thissectiondiscussesthetoolsusedtoyzesimulationdata:theysisWindow,thescriptenvironmentanddataexporttothirdpartysoftwaresuchas moredetailspleaseseethe ysistoolsandtheScriptinglanguagechaptersintheReferenceGuide.ysisThescreenshotbelowshowstheopenysiswindow.Theysiswindowcanbeusedtoplotmonitordata.Avarietyofmonitordatacanbeplottedviathe ysiswindow,dependingonthemonitortype.Spatialrefractiveindexdata,fieldvstime,fieldvsfrequency,fieldsvsspatialdimensions,andpowertransmissionvsfrequencyareafewexamples.Theterminology'Intensity'indicatesasquaredty.Forexample,'Eintensity'means|E|^2.'Exintensity'means|Ex|^2.FielddatafromfrequencymonitorsisalwaysplottedasanIntensity.Ifyouwanttoseetherealorimaginarypartsofthefield,orifyouwanttoobtainphaseinformation,thescriptinglanguagewillberequired.FDTDSolutionscontainsabuiltinscriptinglanguagewhichcanbeusedtoobtainsimulationdata,anddoplottingorpost-processingofdata.Thescriptpromptcanbeusedtoexecuteafewcommands,orthebuiltinscriptfileeditorcanbeusedtocreatemorecomplexscripts.AthoroughintroductiontotheLumericalscriptinglanguagecanbefoundintheScriptingsectionoftheFDTDSolutionsonlineuserguide.DefinitionsforallofthescriptcommandsaregivenintheScriptinglanguagechapterintheReferenceGuide.DataFDTDsimulationdatacanbeexportedintotextfileformatusingthe ysiswindow,intoaLumericaldatafileformat(*.ldf)whichcanbeloadedintoanothersimulation,orintoadata(*.mat)file.InstructionsforexportingtothesefileformatscanbefoundinthelinksundertheScriptingsection.極化surfacesmonpolaritons扮演著重要角色。本例研究的是一個直徑為50nm的相關(guān)文件相關(guān)文件建議讀者先相關(guān)文件。這些文件可以從Lumerical的網(wǎng)頁上得到，也可以在FDTDSolutions的安裝里找到。這lsf文件就是用于高級InthistopicSeeOnlineHelp-> ,[W]I,關(guān)于建模是監(jiān)示器，在兩個監(jiān)視器之間的灰線形成的第三個框顯示TFSF光源的范圍。TFSF光源是平面波，光源的方向（kvector）顯示為紫紅色箭頭而電場的偏振方向（Efieldvector）由藍(lán)色的雙箭頭表示。此光源把模擬區(qū)分為兩個：內(nèi)部區(qū)是全場，包射的平面波和粒子的散射場;（從光源之外的全場中減去入射的平面波）。您可以在用戶指南中光源的部分找到關(guān)于TFSF光源的介紹。TFSF（散射場部區(qū)）在用戶界面(CAD)中，橘黃色的線顯示FDTD的模擬網(wǎng)格。FDTDSolutions含有兩種（自動網(wǎng)）和網(wǎng)格覆蓋區(qū)（meshoverrideregion）。而，當(dāng)特征尺寸小，特別是當(dāng)材料的折射率差比較大或有弧形或斜界面時，必須使用更小何數(shù)據(jù)，模擬跨度的設(shè)置必須足夠大。這是因?yàn)檫吔绲腜ML不只會吸收入射光源，也會場。在這個例子中，PML邊界和結(jié)構(gòu)有一波長左右的距離。Materialexplorer里檢查材料色散模型和實(shí)驗(yàn)數(shù)據(jù)的擬合度。材料色散模型（圖標(biāo)中的FDTDmodel）可以通過改變Materialexplorer里的最大系數(shù)(Maxcoefficients)和容差(tolerance)參數(shù)而調(diào)整。使用比1nm還小的網(wǎng)格尺寸。因此，我們可以從meshrefinementoption里選擇“conformalvariant1““conformalvariant1“通常只適合在低折射率對比的情況下使用，并不一定適合所有的金屬材料（defaultconformalmesh在當(dāng)界面有金屬材料和PEC時會還原成staircase算法）。請參考MeshrefinementandConformalmesh的詳細(xì)內(nèi)容。FDTD模擬中通常是用來檢查FDTDSolutions缺1000fs，而模擬會在場衰減到小于用戶定義的電場強(qiáng)度時自動結(jié)束。以下圖中Ex在32fs自動結(jié)束之前已幾乎下降到零。仿真結(jié)果件“nanowire_theory.csv“里，可以在第一頁找到。左下圖顯示的FDTDSolutions和解析計(jì)算的吸收，散射和消光截面積。很明顯，它們非FDTD2426納米。因1FDTD的結(jié)果在此范圍內(nèi)。正如圖中所345nmEy在此波長的強(qiáng)度穩(wěn)態(tài)分布（以0.5nm網(wǎng)格尺寸計(jì)算）。InthisSetupRunsimulation,plotInthisSetupRunsimulation,plotcrosssectionsPlotnearfielddata模型建立按下STRUCTURES按鈕上的箭 x0y0radiusAg(Silver)-Palik(0-點(diǎn)擊SIMULATION按 產(chǎn)生模擬區(qū).注意如果您的按鈕看起來不象左邊simulationtimex0y0xspanyspanMeshmesh4meshdx1dy1x0y0xspanyspan按下SOURCES按鈕上的箭 并從下拉菜單中選擇TFSF光源。按照下x0y0xspanyspanWavelengthstartWavelengthstop按下YSIS按鈕上的箭 ObjectLibrarySCATTEREDFIELDTOTALFIELD"scat_2D"Setup→x0y0width"total_2D"Setup→x0y0width按下MONITORS按鈕上的箭 并從下拉菜單中選擇MONITORSFIELDTIMExy仿真運(yùn)行,點(diǎn)擊CHECK按 打開MATERIALEXPLORER。點(diǎn)擊FITANDPLOT按點(diǎn)擊VIEWSIMULATIONMESH按鈕(和ZOOM按鈕)檢查仿真時所用的網(wǎng)格點(diǎn)擊RUN按 運(yùn)行模擬切換到分析 YSIS)窗口(請參考以下說明Introductionsectionofthe繪制時域監(jiān)視器數(shù)據(jù)。按照下面的參數(shù)來設(shè)置分析窗口,PLOTTimeMonitor:DatatoFieldvsSCRIPTFILEEDITORIntroductionsectionof從第一頁“plotcs.lsf“文件點(diǎn)擊OPENSCRIPT按鈕瀏覽并打開 文件點(diǎn)擊RUNSCRIPT按 近場繪圖點(diǎn)擊SWITCH按鈕切換回布局模式(layoutmode)編輯網(wǎng)格,dxdy0.5nm按下MONITORS按鈕上的箭頭并從下拉菜單中選擇FREQUENCYusesource1wavelengthcentermonitor2DZ-x0y0xspanyspanRUN一旦模擬已運(yùn)行完畢，繪制場分布:PLOTFrequencyPowermonitor:DatatoIntensityvsSETTINGScolorbarlimitscolorbarmin0max5將繪制出和討論和結(jié)果部分完全相同的圖。問題綜述某些波長上會毫無影響的通過貫通通道，在某些波長上會被轉(zhuǎn)到下拉通道。在這個例子中，波導(dǎo)和諧振腔均為200納米寬，折射率為2.915，包層折射率為1.0。193.1THz（光通信中C--波段的中心波長），且此波長信息被下拉（drop）而不是全部通過(through)。仿真建模FDTDSolutions含有“模式“光源（集成模式求解器）可以使我們在感的波長上計(jì)算結(jié)圍的PML吸收邊界不能太接近結(jié)構(gòu)，不然會截斷導(dǎo)模。 擬時間必須足夠，以便讓光通過波導(dǎo)(5.45μm)并在環(huán)內(nèi)循環(huán)大約十幾次(14次,計(jì)t=d/(c/n)=199μm/(3e8/2.9)m/s=1920fs，因此模擬時間設(shè)置為2000fs。Guide->MonitorsandysisGroups->SimulationtimeandFrequencymonitors里找到。仿真結(jié)果Ez13個明顯的脈沖，和以上的估計(jì)一致（由于光源需要時間入射，我們沒有14個完整的峰）。右下圖顯示貫通通道的傳輸功率。在這例子里，環(huán)行諧振腔的設(shè)置已被調(diào)整到在頻率193.1THz時產(chǎn)生最高傳輸功率。我們可以看到在傳輸功率最大值周圍有小型的波紋，這可以由光都由下拉通道穿過;左下圖是在193.1THz的場強(qiáng)分布，這是最高傳輸功率的頻率。注意傳輸功率和場分布是用不同的監(jiān)視器得到的，傳輸功率是由"frequency andpower"監(jiān)視器得到;而場分部是由"frequency fieldprofilemonitor"得到。這高精度的功率流信息，而profilemonitor能給出準(zhǔn)確的場分布數(shù)據(jù)。193.1THz頻率時能讓最多的功率從下拉通道穿過，可以使用參數(shù)掃描工193.1THz提供最大下拉通道功率的內(nèi)圈半徑。如下圖掃描結(jié)果所示，最適合的內(nèi)圈半徑大約是2.0825微米。近似三維幾何的二維模擬2.915維特性，因此達(dá)到更高效的計(jì)算。集成光學(xué)設(shè)計(jì)人員常用的式是effectiveindexapproximation（有效折射率）2.915SOI（245納米）FDTD245率是neff=2.915。因此，這二維環(huán)行諧振腔濾波器的折射率設(shè)置為2.915來模擬厚度為245納米的三維SOI環(huán)行諧振腔濾波器。 InthisObjectRunsimulation,plottimemonitorandInthisObjectRunsimulation,plottimemonitorandtransmissiondataPlotfieldprofileSweepinnerring按下STRUCTURES按鈕上的箭 并從下拉菜單中選擇RING。按照下x0y0innerradiusouterradiusx0yxspanyspan挑選輸入波導(dǎo)，點(diǎn)擊中的DUPLICATE按 （或使用鍵盤上的簡捷鍵(x,y)(02.6μm“OK”FDTD點(diǎn)擊SIMULATION按 產(chǎn)生模擬區(qū).注意如果您的按鈕看起來不象左邊simulationtimex0y0xspanyspan光按下SOURCES按鈕上的箭 并從下拉菜單中選擇MODE光源按照下x-yyspan3FrequencyspanGENERALSELECTMODESELECTMODE按鈕，等待模式計(jì)算結(jié)束。注意列表中的第一個模式是有被強(qiáng)調(diào)，點(diǎn)擊監(jiān)視按下MONITORS按鈕上的箭 并從下拉菜單中選擇按下MONITORS按鈕上的箭頭并從下拉菜單中選擇FREQUENCYmonitorlinearx0y0yspan2按下GROUPS按鈕上的箭頭 并從下拉菜單中選擇YSISGROUP。在YSIS→Variables圖標(biāo)下添加一個result"fmax",，并在YSIS→ScriptT=-transmission("power");#T=-transmission("power");#gettransmissiondatafrompowerf=getdata("power","f");#getfrequencydatafrompowermonitorpeak=findpeaks(T,3);#findthe3peaksintheTransmissionspectrumpeak0=find(f(peak),193.1e12);#pickthepeakclosestto193.1THzfmax=f(peak(peak0));Setup-x-y-選擇這兩個監(jiān)視器，并將其添加到分析組。用MOVE OBJECTTREE中的分析組下，并用MOVE (x,y)(2.42.6μmMONITORSFIELDTIMEx-y-"time_through",(x,y)(2.42.6μm。運(yùn)行仿真，模擬結(jié)果繪圖點(diǎn)擊RUN按鈕運(yùn)行模擬切換到分析(YSIS)窗口(請參考以下說明IntroductionsectionoftheEz。按照下面的參數(shù)來設(shè)置分析窗口,PLOTTimeMonitor:DatatoFieldvs繪制頻域監(jiān)視器的透射率。按照下面的參數(shù)來設(shè)置分析窗口,PLOTFrequencyPowermonitor:Datatox-transmissionvs場分布繪圖點(diǎn)擊SWITCH按鈕切換回布局模式(layoutmode)按下MONITORS按鈕上的箭頭并從下拉菜單中選擇FREQUENCYusesource2minimumfrequencyumfrequencyx0y0xspan7yspan7RUN一旦模擬運(yùn)行完畢，繪制場分布:PLOTFrequencyPowermonitor:DatatoIntensityvsEFrequency193.1PLOT。切換到/optimizationandparametersweep(IntroductionsectionoftheGettingStartedexamples)點(diǎn)擊CREATENEWPARAMETERSWEEP按 按照下面屏幕截圖的設(shè)置參數(shù)掃描，按確定（APPLYOKRUNSCRIPTPROMPTsectionoftheGettingStartedexamples)fmax=getsweepdata("sweep","fmax");r=getsweepdata("sweep","r");plot(r*1e6,transpose(pinch(fmax)*1e-12),"innerradiusfmax=getsweepdata("sweep","fmax");r=getsweepdata("sweep","r");plot(r*1e6,transpose(pinch(fmax)*1e-12),"innerradius(THz)","Frequenciesatwhichmaxpowerdropoccurs","plot本范例目的是示范如何使用FDTDSolutions來分析光子晶體腔，并得到頻率(resonantfrequency)、品質(zhì)因數(shù)(Qualityfactor)、腔的模態(tài)分布。我們學(xué)習(xí)如何找尋感的模態(tài)以及量測品質(zhì)因數(shù)(Q值)后，會使用PSO(particleswarmoptimization)相關(guān)文件建議讀者先相關(guān)文件。這些文件可以從Lumerical的網(wǎng)頁上得到，也可以FDTDSolutions的安裝里找到。這fsp文件含有設(shè)計(jì)參數(shù)和模擬運(yùn)算的所有l(wèi)sf文件就是用于高級注意：本范相關(guān)文件建議讀者先相關(guān)文件。這些文件可以從Lumerical的網(wǎng)頁上得到，也可以FDTDSolutions的安裝里找到。這fsp文件含有設(shè)計(jì)參數(shù)和模擬運(yùn)算的所有l(wèi)sf文件就是用于高級InthisSimulationsetupSimulationysis:ysis:OptimizationofinnerSeeFDTDSolutionsOnlinehelp->CavitiesandFDTDSolutionsOnlinehelp->仿真建模Ta2O5(2.0995)，包含排列成六角晶格之空氣柱，晶格常(latticeconstant)575nm194nm，并藉由移除正中心空氣柱而形成一腔，最內(nèi)圈空氣柱半徑為100nm，結(jié)果如下圖。FDTDSolutions建立此結(jié)構(gòu)，首先建立一矩形平板，接著加入圓柱狀結(jié)構(gòu)至平板中。在平板與圓柱的位置中，為使圓柱取代平板，我們使用meshorder來選擇圓柱的折射率,而不是平板的折射率。有關(guān)meshorder的細(xì)節(jié)，請參照Reference兩個dipole光源(綠色箭頭代表磁場方向)被用于激發(fā)模態(tài)，我們不將dipole置于光子晶體結(jié)構(gòu)中心是為了減少光源處在模式零點(diǎn)的機(jī)會。dipole光源將入射能量注入模擬范圍，部分dipole輻射將被耦合至腔模態(tài)中并緩慢地衰減，無法耦合進(jìn)入腔模態(tài)的在FDTDSolutions模擬中，頻域監(jiān)視器(frequency monitors)采用了時域訊號 data)的離散轉(zhuǎn)換來計(jì)算模態(tài)。顯然，我們并不想要包含初始模擬的那些訊號的能量保留為腔的模態(tài)。您可在下頁(構(gòu)建說明)看到，我們可使用監(jiān)視器中的切趾(apodization)功能去選擇我們想要的時間訊號。更深入的討論有關(guān)監(jiān)視器apodization的說明可在OnlineUserGuide->Monitorsand PerfectlyMatchedLayerPML)PML邊界吸收入射輻射，其目的是吸收所有離開腔的輻射。因此，相當(dāng)重要的是腔與PML邊界須(non-propagatinglocalevanescentfields)。一個簡單的規(guī)則，在結(jié)構(gòu)以上和以下保留至少(Z<0)zmin的邊界上使用法在結(jié)果中顯現(xiàn)(因?yàn)橛脤ΨQ性邊界只能激發(fā)對稱的模態(tài))。在這個光子晶體腔中，有近似TE的模態(tài)而消除近似TM的模態(tài)。注意，dipolez=0z=0平面有一個指向電場，藍(lán)色對稱性邊界條件是特意的，它表示，電場應(yīng)該位于沿著(平行)此邊界。在FDTDSolutions中，大部分的光源包含藍(lán)色箭頭(表電場方向)，它應(yīng)該總是要位于藍(lán)色邊網(wǎng)(meshcell)λcfn3e8160e122.0995890nm，我λ/10x方向每個周期有八個網(wǎng)格我們可以得到網(wǎng)格大小575nm8=71.875nm(<λ/10)。因?yàn)閥575*sin(60)nmy方向網(wǎng)格會小于x方向。如此設(shè)定，可得到較為可靠的精確度。(FDTD也必須是晶格常數(shù)的整數(shù)倍。因此，我們設(shè)定FDTDxspan575*12nm，yspan575*sin(60)*12nm。(FDTDSolutions中觀察網(wǎng)格)，能夠看到在每一個圓柱上的網(wǎng)格，都FDTD需要在每一個圓柱上切出相同的網(wǎng)格。假(indexmonitor)來確認(rèn)被切成網(wǎng)格模擬時間(Highqualityfactor)腔模擬為一例外(HighQmode衰減非常慢，HighQ腔模擬(apodization)的結(jié)合，使我們能夠不需要等到時域場完全衰減，即可準(zhǔn)確的計(jì)算品質(zhì)因素(qualityfactor)與腔模態(tài)(modes)，然而，使用此方法仍需要，當(dāng)模擬提早結(jié)束時。其他量測結(jié)果像是powertransmission和fieldamplitudes模擬結(jié)果模擬包含Q ysis群組中包含time監(jiān)視器且并未放置于模擬中心，其原因是由于dipoles并未到峰值：只需修改Qysis→ysis->Variables中的number_resonances也可得到電場對時間函數(shù)的輸出曲線(下左圖)及峰值(下右圖)，品質(zhì)因素的計(jì)算將在OnlineHelp中的CavitiesandResonators章節(jié)仔細(xì)討論。 進(jìn)階分析：對稱性邊界條201THz擁有最大的品質(zhì)因素，我們需要藉由幾次的模擬來找到適合的孔洞內(nèi)徑。由于模態(tài)在x及y方向具有對稱性，可以使用anti-symmetric/symmetric邊界條件設(shè)定UserGuideSimulationChoosingbetweensymmetricanti-symmetricBCs討論，我們可看見有模態(tài)的電場在x=0平面上具稱性，y=0xminyminanti-symmetric/symmetric邊界條件所得到.進(jìn)階分析：孔洞內(nèi)徑優(yōu)化FDTDSolutions內(nèi)建優(yōu)化功能，我們選擇使用PSO(ParticleSwarmOptimization)算法，用戶也能夠自定義其他算法。有關(guān)算法的細(xì)節(jié)，詳見Onlinehelp中UserGuide的RunningSimulationsand ysis->Optimization。半徑結(jié)果為91.9nmInthisCreatePCandcheckmaterialAddsourcesInthisCreatePCandcheckmaterialAddsourcesandmonitors.Runsimulationandgetdata.Optimizeinnerhole創(chuàng)建光子晶體與驗(yàn)證材料折射率點(diǎn)擊STRUCTURES箭 x0y0z0xspanyspanzspan1點(diǎn)擊COMPONENTS