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1、西南交通大學(xué)碩士學(xué)位論文超短脈沖光束的傳輸特性研究姓名：柳紅英申請(qǐng)學(xué)位級(jí)別：碩士專業(yè)：通信與信息系統(tǒng)指導(dǎo)教師：羅斌20070501西南交通大學(xué)碩士研究生學(xué)位論文第1I頁(yè)沖光束自聚焦特性的影響．由于時(shí)空耦合與介質(zhì)色散有關(guān)，使得群速度色散GVD和三階色散TOD都會(huì)引起時(shí)間脈沖的另一延遲。軸上時(shí)間波形向軸外偏移，成為旁軸脈沖，其偏移量缸與傳播距離、色散成正比，隨著傳播距離的增大，脈沖的傍軸延遲相應(yīng)增大，色散越大，傍軸延遲越大．TOD和GVD也都引起脈沖展寬，光強(qiáng)下降，TOD同,GVD的影響相比，脈沖展寬更快，強(qiáng)度下降也更多，且TOD
2、使脈沖產(chǎn)生不對(duì)稱，后沿有一個(gè)長(zhǎng)的拖尾。而這時(shí)空間光強(qiáng)分布由于受到脈沖延遲的影響，中心軸上的光強(qiáng)極小，近場(chǎng)空間分布幾乎沒(méi)有發(fā)生變化，可見色散較好地抑制了自聚焦效應(yīng)。關(guān)鍵詞：超短超強(qiáng)脈沖光束；菲涅耳衍射；時(shí)空聚焦；自陡峭效應(yīng)；自聚焦西南交通大學(xué)碩士研究生學(xué)位論文第1
3、I頁(yè)AbstractWiththerapiddevelopmentoflaserdrivertechnologyininertialconfinementfusionOc職ultrashortpulsedbeamswemappHedinhighpowerlasersy
4、stemgradually．Inultrashortpulsedbeamspropagation,generallyspeaking,small-scaleself-focusingwasrestrainedpreferably．Andthebandwidthofultrashortpulsedbeamsleadstomanynewquestions．Thereforethestudyofultrashortpulsedbeamshasbeenafocusofthescientificresearch．Onthebasisof
5、themodified(3+1)-dimensionalnonlinearSchrodingerequation，symmetryspmFouriertransformmethodasthemethodofnumedcalsimulation,weinvestigatethepropagationoffemtosecondpulsedbeamsinfreespaceandnonlineardispersivemedia．Themainresultsachievedinthistheslscanbe輒玎nnlaIizedasfo
6、llows：1．TheNear-fieldFresneldiffractionmodulationofultrashortpulsedbeamsinfreespaceisstudiedintheorybyuseofthesimulation．TheFresneldiffractionpattemofregularshapesScreensuchasrectangularaperture，serratedcircleapertureandSuper-Gaussianbeam．Thediffractionmodulationofu
7、ltrashortpulsed-laserislessthanCWlaser：Andthetransmissionfeaturesoftheultra-shortpulsed-laserpassingthroughtheserratedapertureandspatialfilterisstudiedinallusiontocleanandllnifb眥intensitydistributioninthehigh-energyultrashortpulse-lasersystem．especialdiffractionofSu
8、per-Ganssianbeam．Theresultshow：Theaxialpulseenvelopepropagatesundistortedwhenpropagatinginfreespace．butthespatiotemperalcouplingcanaffectitsintensity．2．Theself-focnsingpropertiesoffemtosecondpulsesinanonlineardispersivemediumisinvestigatednumericallyintheregimewhere
9、thecombinedeffectsofdiffraction,Space-timecoupling,normaldispersion,andcubicnoulmearityleadtopulsesplitting．Themainworkandachievementsasfo
