涡旋光束的深聚焦特性

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1、西南交通大学硕士学位论文涡旋光束的深聚焦特性姓名：张志明申请学位级别：硕士专业：光学工程指导教师：王喜庆20080401西南交通大学硕士研究生学位论文第1I页数对聚焦区域内光强分布、相干度和偏振度的影响。结果表明，入射光束的有效相干长度和聚焦透镜的最大数值孔径角的取值变化都会对光强分布、相干度和偏振度产生影响。研究还发现入射的线偏振光场经高数值孔径透镜聚焦后会被去偏振。推导了深聚焦涡旋光束的光场和轨道角动量的表达式，研究了深聚焦涡旋光束的相位和轨道角动量分布。通过等相位线图，特别分析了聚焦后光场的x方向分量的相位分布。此外，还分

2、析了聚焦透镜的数值孔径对焦平面内等相位线分布和轨道角动量分布的影响。根据轨道角动量沿z轴的分布特点，发现涡旋光束的轨道角动量的最佳应用位置为焦平面附近。关键词：矢量Debye衍射积分、深聚焦、涡旋光束、偏振、介质面、双折射晶体、轨道角动量西南交通大学硕士研究生学位论文第lII页AbstractResearchesonandapplicationsoftheopticalvortexbeamshaverecentlygeneratedgreatresearchinterest，whichhasresultedinanewbranc

3、hofsingularopticsinmodemoptics．Opticalvortexbeamspossesswave·frontdislocationswherethephasevaluesareundefined(alsoreferredtoasphasesingularities)andtheamplitudevanishestozero．Suchbeamscanbegeneratedbyusingthespatiallightmodulatorsorthespatialphasesplates，andpossessah

4、elicalphasestructure．IthasbeenknownthatsuchvortexbeamscarryorbitalangularmomentumandCanbeappliedtotrapandrotateparticlesandrelatedapplications．Andthedarkopticalvorticescanbecomethephysicalinstrumenttocreateopticalvortextweezers．Theuniqueandnovelpropertiesofvortexbeam

5、shaveopenedavarietyofnewpossibilitiesforsingularopticsapplications．Soitisofgreattheoreticalandrealisticsignificancetoinvestigatethepropagationpropertiesofvortexbeams．ThevectorialDebyediffractionintegralmethodisintroducedinthefirstchapter．SinceBessel-Gaussian(BG)beams

6、ofthenon-zeroorderCanbesetasvortexbeams，thetightlyfocusingpropertiesofBGbeamsofthenon-zeroorderunderseveralconditionsarestudiedindetail．ThefocusingpropertiesofcylindricallypolarizedBGbeamsfocusedbyahighnumerical—apertureobjectiveisstudied．Thelightfieldexpressionsofcy

7、lindricallypolarizedBGbeamsfocusedbyahighnumerical-apertureobjectivearederived．Numericalcalculationsaretakentoanalyzetheinfluencesofvaryingvaluesoftheparametersonthelightintensitydistributionatthefocalplaneandinthevicinityoffocus．Byadjustingthevaluesofcorrespondingpa

8、rameters，theintensitydistributioninthefocalregionCanbecontrolled，andbottlebeamsandflat—toppedbeamsareobtainedwhichpossessthecharact