有機(jī)環(huán)形共軛鏈分子三階光學(xué)非線性的Z-掃描研究.pdf

1、東南大學(xué)碩士學(xué)位論文有機(jī)環(huán)形共軛鏈分子三階光學(xué)非線性的Z掃描研究姓名：姚文杰申請(qǐng)學(xué)位級(jí)別：碩士專業(yè)：光學(xué)工程指導(dǎo)教師：崔一平呂昌貴20070401AbstractTwophotonabsorption(2PA)isathirdordernonlinearopticalprocess，inwhichnmolecule(atom)ofamediumingroundstatesimultaneouslyabsorbstwophotonsand

2、thentransitst0anexcitedstateMoleculeswithIarge2PACROSSsectionshave剖嚙陷虻tedconsidetableattentionduetoanumberofpotentialapplicationssuchasopticallimitingstabilizationthreedimensionalopticaldatastoragetwophotonabsorptionindu

3、cedfluorescencemicroscopyandopticaldynamictherapyItisimportanttostudyontherelationbetweenthemolecularstructureandthethirdordernonlinearopticalpropertiesinordertoenhancethe2PAcrossseetiunMoleculeswitIllarge2PAcrosssection

4、reportedatpresentgenerallyhaveaonedimensionallincarchainstructure，suchasmoleculewithnDⅦA，肌丌DA1tA，肛兀A丌D，orA—冗D矗Astructure，oramultidimensionaIbranchstructureorndendrimersWuctorePorphyrinstudiedinthispaperhasaparticularcirc

5、ularconjugatedchainandthusadifferentchargetransfermode，whichmakesitownalargenonlinearabsorptionpropertyDuetoitslowopticalpowerlimitingthreshold1argedynamicrange，rapidandbroadhandresponse，andhighlineartransmithance，porphy

6、rinshavereceivedagreatdealofattemionreccutly∞novelpotentialopticalpowerlimitingmaterialsSofar研nciplesofnonlinearabsorptionandopac州powerlimitingaboutporphyrinhasbeenstudiedwidelyHowev日mostofthestudiesinliteraturewerefocus

7、edollasingleshortwavelength(usually532ran)whilethenonlinearabsorptionatlongwavelongtheshasnotbeenreportedyetHere，theNonlinearabsorptionpropertiesofanewlysynthesizedmolecule5，10，15。20tetrakis(phexadecyloxyphenyl)porphyrin

8、arestudiedexperimentallyandtheoreticallyinthispaperUsingananosecondo口“calparametricoscillator(OPt))pumpedbyaQswitchedNd：YAGlaserpulse，weobtaintheopenapertureZscandataoverthewaveleogthesrangingfrom710nmto820nmAccordingtot

9、heZscantheoryfor2PAwegetthe2PAspccuumofthissampleandfindthismaterialhasalargetwophotonabsorptioncrosssectionatwavelengthsof750mThepeak2PAcrosssoclionvalueisaround132xlO“cmJphoton～Whenpumpedbyallintensityinputlaserpulse，t

10、heporphyrinshowsobservablyexcitedststPreabsorpaonwhichisanalysedbythetwophotoninducedexcited—staleabsorptionmodelToimprovethesensitivityandstabilityoftheZscanexperiment，softieimportantparameterssuchastheapertureradius，th

11、edistancebetweenthelensfocusandtheapcl“tore。andthelensfocus，areanalyzedbynumericalsimulationResultsshowthatthereisanoptimalf／dvaluewhichmakesthenonlinearrefractionandnonlincarabsorptionphenomenaobservedobviouslyatthesame

12、timeMoreovertheinfluencesofnonlinearabsorptionandnunlinearrefructivityontheclosedapertureZscancugvearediscmsedhereWefmdthatwhetherthepcakvalleystructureexistsornotdependsolltheratio(腳ofthenonlinearrefractioncoefficientto

13、thenonlinearabsorptioncoefficientThatistosayifthenormalizedtransmittancecurvehasaobviouspeakvalleystructure，theratioshouldsatisfylRI243Otherwise，thepeakorvaJkywillvanishAnofthesesimulationstudiesprovidetheoreticalguideli