Ultrashort laser pulse interaction with photo-thermo-refractive glass.pdf

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1、ULTRASHORTLASERPULSEINTERACTIONWITHPHOTO-THERMO-REFRACTIVEGLASSbyLEOA.SIIMANB.S.UniversityofFlorida,2001AdissertationsubmittedinpartialfulfillmentoftherequirementsforthedegreeofDoctorofPhilosophyintheCollegeofOpticsandPhotonicsattheUniversityofCentralFloridaOrlando,FloridaSum

2、merTerm2008MajorProfessor:LeonidB.Glebov333536933353692008©2008LeoA.SiimaniiABSTRACTPhoto-thermo-refractive(PTR)glassisanidealphotosensitivematerialforrecordingphasevolumeholograms.Itisahomogeneousmulti-componentsilicateglassthatdemonstratesalltheadvantagesofopticalglass:ther

3、malstability,highlaserdamagethreshold,andawidetransparencyrange.Moreovertheabilitytorecordphasepatterns(i.e.spatialrefractiveindexvariations)intoPTRglasshasresultedinthefabricationofvolumehologramswithdiffractionefficiencygreaterthan99%.Theconventionalmethodofrecordingahologr

4、aminPTRglassreliesonexposuretocontinuous-waveultravioletlaserradiation.InthisdissertationtheinteractionbetweeninfraredultrashortlaserpulsesandPTRglassisstudied.ItisshownthatphotosensitivityinPTRglasscanbeextendedfromtheUVregiontolongerwavelengths(near-infrared)byexposuretoult

5、rashortlaserpulses.ItisfoundthatthereexistsafocusinggeometryandlaserpulseintensityintervalforwhichphotoionizationandrefractiveindexchangeinPTRglassafterthermaldevelopmentoccurwithoutlaser-inducedopticaldamage.PhotoionizationofPTRglassbyIRultrashortlaserpulsesisexplainedinterm

6、sofstrongelectricfieldionization.ThisphenomenonisusedtofabricatephaseopticalelementsinPTRglass.TheinteractionbetweenultrashortlaserpulsesandvolumehologramsinPTRglassis122studiedintwolaserintensityregimes.Atintensitiesbelow~10W/cmpropertiessuchasdiffractionefficiency,angulardi

7、vergence,selectivity,andpulsefronttiltareshowntoagreewiththetheoryoflineardiffractionforbroadspectralwidthlasers.Avolumegratingpairiiiarrangementisshowntocorrectthelaserpulsedistortionsarisingfrompulsefronttiltandangulardivergence.Athigherintensitiesofirradiation,nonlineargen

8、erationanddiffractionofthirdharmonicisobservedforthreetypesofinterac