溶剂对金属纳米材料光学非线性的影响

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1、哈尔滨工业大学理学硕士学位论文摘要由于具有不同于体材料的特性，目前纳米材料光学非线性的研究成为光电子领域的一个热门的课题。本论文着重研究了不同溶剂对金属纳米材料的光学非线性影响。在本论文中，考虑溶剂和纳米材料的极性与介电函数，应用Lorentz-Lorenz关系，从理论上推导出偶极子的光学吸收截面，分析了溶剂对纳米材料光学非线性的影响，并给出了金属纳米粒子从反饱和吸收到饱和吸收的转化条件。分析了光致重新取向，光致表面等离子体，光致热体积膨胀等对非线性体系自聚焦(或散焦)性质的影响。光致极化重新取向只会导致自聚焦;光致表面等离子体会导致自散焦，

2、这是由于在激光激励条件下，表面等离子体的电荷密度发生改变，使纳米材料介电函数也跟着发生改变，从而改变溶液的折411率;光致热体积膨胀可以导致自聚焦和自散焦，这依赖于溶液的膨胀系数。研究了纳米材料碳和碳载铂水溶液非线性透射的特性，观察到了反饱和吸收到饱和吸收的转化的现象，实验结果与吸收理论相吻合。给出了在532nm,Sns脉宽实验条件下，[MOOS3Cu3(4-pic)6)J的乙睛溶液由自散焦到自聚焦变化的解释。认为[MOOS3Cu3(4-pic)6]'I的乙睛溶液的自散焦来源于激光热效应所引起的体积膨胀，而自聚焦则是来源于激光诱导重新取向。关

3、键词金属纳米材料;反饱和吸收;自聚焦;自散焦;激光诱导表面等离子体哈尔滨工业大学理学硕士学位论文AbstractResearchofnano-materialsiscurrentlyaninterestingsubjectinoptaelectronicscommunity,becausenano-materialshavenewpropertiesthatbulkmaterialsdonothave.Inpresentdissertation,westudiedthedifferentsolventeffectsonnonlinearopt

4、icalpropertiesofmetalnano-materialsespecially.Inthiswork,byusingthesolventandnano-materialpolarizationanddielectricfunction,wederivedtheelectricdipolaropticalabsorptioncross-sectiontheoreticallyviatheLorentz-Lorenzrelation,andanalyzedthesolventeffectonopticalnonlinearityofm

5、etalnano-materials.Theconditionofthetransformationfromreversesaturableabsorption(RSA)tosaturableabsorptionwasproposedTheeffectoflaserinducedreorientation,laserinducedsurfaceplasmonandlaserinducedthermalheatexpansionofvolumewereanalyzed.Laserinducedreorientationonlyleadstose

6、lf-focuse.Laser-inducedsurfaceplasmonleadstoself-defocuse.Thedielectricfunctionsofnano-materialschangewiththevariationoftheelectronicdensityoflaser-inducedsurfaceplasmon,sotherefractiveindicesofthesolutionchangealso.Laserinducedthermalexpansionleadstoself-focuseordefocuse,w

7、hichdependsonthesolventexpansioncoeficient.Weinvestigatedthenonlinearopticaltransmittancepropertiesofnano-materialcarbonandPVCinwatersolvent.Thetransformationfromreversesaturableabsorptiontosaturableabsorptionwasobserved.Theexperimentalresultsagreewiththatofabsorptiontheory

8、.Theinterpretationofthechangefromtheself-defocusetotheself-focuseofCMo0S3Cu3(4-pic