ITEM VIEW

Spectral and temporal modulation and characterization of femtosecond ultra-short laser pulses

dc.contributor.advisorRohwer, Erich G.en_ZA
dc.contributor.advisorSchwoerer, Heinrich P. H.en_ZA
dc.contributor.advisorNeethling, Pieter H.en_ZA
dc.contributor.authorMbanda Nsoungui, Gaelle Carineen_ZA
dc.contributor.otherStellenbosch University. Faculty of Science. Dept. of Physics.en_ZA
dc.date.accessioned2012-11-28T08:27:05Zen_ZA
dc.date.accessioned2012-12-12T08:16:18Z
dc.date.available2012-11-28T08:27:05Zen_ZA
dc.date.available2012-12-12T08:16:18Z
dc.date.issued2012-12en_ZA
dc.identifier.urihttp://hdl.handle.net/10019.1/71883
dc.descriptionThesis (MSc)--Stellenbosch University, 2012.en_ZA
dc.description.abstractENGLISH ABSTRACT: Ultra-short laser pulses are useful in materials processing like melting and cutting metals, and medical applications such as surgery and many other fields. In this study, we characterize and control the temporal shape of the ultra-short pulses generated from a Ti:Sapphire femtosecond laser. It operates in the near infra-red spectral region, with a centre wavelength of 800 nm. The 4f pulse shaper is the main setup used to modulate spectral shape and characterize the laser pulse. The shaper consists of two diffraction gratings, two cylindrical lenses and a computer controlled liquid crystal spatial light modulator (LC-SLM). Gratings, lenses and LC-SLM are arranged in a 4f geometry, f being the focal length of the lenses. This setup is first analysed analytically and numerically using Fourier transform and the results obtained are then compared to those obtained from the experiment. The characterization of ultra-short pulses was done using three different autocorrelation techniques such as the intensity autocorrelation, the interferometric autocorrelation, and the pulse shaping autocorrelation which can act as interferometric autocorrelation when a nonlinear crystal ß-barium borate (BBO) is placed exactly at the position of the experiment. These characterization techniques are based on the interaction between the laser pulse and a replica of it with a nonlinear crystal. The setups were implemented and measurements using the last two techniques were successfully conducted, with the pulse duration result in the range from 80-86 fs.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Ultrakort laserpulse het baie nut in verskeie velde waaronder materiaalprosessering (soos die smelt en sny van metale) en mediese toepassings (soos chirurgie) maar net twee voorbeelde is. In hierdie studie karakteriseer en beheer ons die vorm van n ultrakort laserpuls, afkomstig vanaf n Ti:Saffier femtosekonde laser, in tyd. Die laser straal in die nabyinfrarooi spektrale gebied uit met n sentrale golflengte van 800 nm. Ons gebruik n sogenaamde 4f-pulsvormer om die spektrum van die laserpuls te moduleer en die laserpuls te karakteriseer. Die vormer bestaan uit twee diffraksieroosters, twee silindriese lense en n rekenaarbeheerde vloeibare kristal ruimtelike-lig-modulator (LC-SLM). Die diffraksieroosters, lense en LC-SLM is in n 4f-geometrie gerangskik, met f die brandpunt van die lense. Die opstelling is eers analities en numeries beskou deur van Fourier-transformasies gebruik te maak waarna die resultate wat verkry is met die van n eksperiment vergelyk is. Die karakterisering van ultrakort laserpulse was met drie verskillende outokorrelasie tegnieke gedoen, naamlik n intensiteits-outokorrelasie, n interferometriese-outokorrelasie en n pulsvormer-outokorrelasie. Die pulsvormer kan as n interferometriese-outokorrelator optree indien n nie-lineêre kristal ß-bariumboraat (BBO) by die uitset van die pulsvormer geplaas word. Hierdie karakteriseringstegnieke is gebaseer op die interaksie tussen die oorspronklike laserpuls en n kopie van die laserpuls in n nie-lineêre kristal. Die nodige opstellings virdie metings is gemaak en die metings was suksesvol uitgevoer. Die pulslengte wat gemeet is, is in die orde van 80-86 fs.af_ZA
dc.format.extentxiv, 76 p. : col. ill.
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.subjectUltra-short pulsesen_ZA
dc.subjectSpectral modulationen_ZA
dc.subjectSpatial light modulatoren_ZA
dc.subjectFemtosecond lasersen_ZA
dc.subjectDissertations -- Physicsen_ZA
dc.subjectTheses -- Physicsen_ZA
dc.subject.otherPhysicsen_ZA
dc.titleSpectral and temporal modulation and characterization of femtosecond ultra-short laser pulsesen_ZA
dc.typeThesisen_ZA
dc.rights.holderStellenbosch Universityen_ZA


Files in this item

Thumbnail
Thumbnail

This item appears in the following Collection(s)

ITEM VIEW