SNLO_Help帮助文件

SNLOHelpArleeSmithOctober13,20091AboutSNLOSNLOiswrittenandmaintainedbyArleeSmithatAS-PhotonicsinAlbuquerque,NewMexico.ItiswritteninAPLprogramminglanguage.Itiscon-tinuouslyupdatedwiththelatestversionavailableonlineatleSNLO.PDFthatisinyourSNLOfolder,alsoavailableonlineatles/SNLO.pdfShouldyouwishtoreferenceSNLOinapublicationpleaseuse:`SNLOnonlinearopticscodeavailablefromA.V.Smith,AS-Photonics,Albuquerque,NM'Comments,questions,andsuggestionsarewelcome.Sendthemtomeat:[e-mail]*.DATlesinSNLOdirectoryareoutputdatalesandmaybedeletedtorecoverdiskspace.Additionalcrystalinformationisavailableinthe135pagebibliographyCRYSTALS.PDF(intheSNLOdirectory,andavailableonline),andfromtheleBetan2.pdfwhichincludestablesofreportedtwo-photonabsorptioncrosssectionsandnonlinearre-fractiveindexcoecients.ThislemaybefoundinyourSNLOfolder.2Functions2.12D-mix-LP2D-mix-LPissimilartoPW-mix-LPexceptithan-dlesthefullspatialprolessoitcanrealisticallymodelcircularorellipticalbeamswithGaussianorSupergaussiantransverseproles.Itincludesdirac-tion,birefringentwalko,displacedbeams,etc.forpulsedorcwlight.Thelightisassumedtobemonochromatic,andthepulsesareassumedtobelongenoughthatgroupvelocityeectsareunim-portant.Maxwell'sequationsareintegratedusingsplit-stepmethodstogivetruediractivecalcula-tions.Modelingmethodsaredescribedindetailinpapers\Phasedistortionsinsum-anddierence-frequencymixingincrystals,JOSABvol.12p.49(1995),and\Comparisonofanumericalmodelwithmeasuredperformanceofaseeded,nanosecondKTPopticalparametricoscillator,JOSABvol.12p.2253(1995).Thesepapersareavailableonlineat(seeReadme.txtleaboutmemoryallocation).For12Mb,thegridcanbeaslargeas128128,for180Mbitcanbeupto512512.A3232gridisusuallyadequate.IsuggestyouusethemuchfasterPW-mix-LPrsttondreasonablevaluesfortheinputparameters.Outputsincludebeamtiltsinthewalkodirection(Tilt),time-dependentM2valuesinthewalkodirec-tionandperpendiculartoit(M-wandM-pbuttons),timeintegratedM2values(writtenattopofplotsoftimedependentM2),andwavefrontcurvatureattheplanespeciedbythepropagationdistanceinputparameter.Youshouldmakesuretheseresultsareconvergedbyincreasingthegriddensitybyfactorsoftwountiltheanswersstabilize.Usuallyagridof3232or6464isadequate.Phasesareplottedosetby+sotherangeis(0to2)insteadof(to).Theinputpulses(ifnotcw)areallcenteredatt=0.Runsstartatt=0andprogresstolatertime.Timest0arenotmodeledbecauseofthesymmetryaboutt=0.Theresultsarewrittentoasciiles*INT.DATand*PH.DAT,wherethe*INTles(*PHles)areirradiance(phase)outateachtimestepwithcolumnsx,y,irr(t1),irr(t2),....TheasciilesSIGBEAM.DAT,IDBEAM.DATandPMPBEAM.DATcontaintime,power,phase,M2x,M2y,X-curvature,Y-curvature,andX-tiltincolumns18(whereXisthewalkodirection).TheuenceiswrittentotheasciileFLUENCE.DATwithcolumnsx,y,signaluence,idleruence,pumpuenceatthepropagationdistancespecied(from1exitfaceofcrystal).FLUENCF.DATistherelativefarelduenceangulardistributionwithcolumnsx-angle,y-angle,signaluence,idleruence,pumpuence.Actualxandyangles(inradians)arefoundbymultiplyingx-angleory-anglebythewavelength(inmeters)ofthesignal,idler,orpumpwave.ThesedistributionsareFouriertransformsoftheeldsatthecrystalexitface.Noncollinearphasematchinginthecriticalplanecanbefakedbyusingthewalkoparameter.Forexam-ple,ifthesignal'struewalkoangleis50mradandyouwanttopropagatethepumpalongthisdirec-tion,youwouldspecify50mradforboththesignalandpump.Youmustthencompensatebyadjustingtheidlerwalkotobe50idler=pump.Inotherwords,fakewalkomustbecompensatedtomaintainphasematch,butrealwalkoisnotcompensated.Ofcourse,thetiltswillnotreecttheactualvaluesforthefakewalkobutwillbethedeviationfromtheinputbeamtilt.ThelastusedinputsetissavedinMIX.SFsoifyouwouldliketosavethosesettingsforlaterrecall,copyMIX.SFtoanotherlenametostore.CopythelebacktoMIX.SFtorestore.2.22D-mix-SP2D-mix-SPmodelssingle-passmixingwithdirac-tion,birefringentwalko,groupvelocitywalko,andgroupvelocitydispersion.ThisisaslowmemoryhogsotrytoselectthebestvaluesforthetimeandspatialgridsusingthefasterfunctionsPW-mix-SP,PW-mix-LP,and2D-mix-LPbeforerunningit.Themaximumsizesofthespatialandtemporalgridsde-pendontheamountofmemoryallocatedtoSNLO(seeReadme.txtleaboutmemoryallocation).A3232128gridrequires35MballocatedtoSNLO.Thisshouldbeadequateformostsituations.ThecalculationisbasedonintegratingMaxwell'sequationsusingsplit-stepFFTmethodstogiveaccu-ratediractiveandgroupvelocitysimulations.Meth-odsaredescribedinpapers\Numericalmodelsofbroadbandwidthnanosecondopticalparametricos-cillators,JOSABvol.16p.609(1999);\Phasedis-tortionsinsum-anddierence-frequencymixingincrystals,JOSABvol.12p.49(1995);and\Com-parisonofanumericalmodelwithmeasuredperfor-manceofaseeded,nanosecondKTPopticalpara-metricoscillator,JOSABvol.12p.2253(1995).Thesepapersareavailableonlineat