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Spectral and temporal modulation and characterization of femtosecond ultra-short laser pulses
Thesis (MSc)--Stellenbosch University, 2012.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2012
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| _version_ | 1867613841485987840 |
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| access_status_str | Open Access |
| author | Mbanda Nsoungui, Gaelle Carine |
| author2 | Rohwer, Erich G. |
| author_browse | Mbanda Nsoungui, Gaelle Carine Rohwer, Erich G. |
| author_facet | Rohwer, Erich G. Mbanda Nsoungui, Gaelle Carine |
| author_sort | Mbanda Nsoungui, Gaelle Carine |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MSc)--Stellenbosch University, 2012. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/71883 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:42:33.557Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2012 |
| publishDateRange | 2012 |
| publishDateSort | 2012 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/71883 Spectral and temporal modulation and characterization of femtosecond ultra-short laser pulses Mbanda Nsoungui, Gaelle Carine Rohwer, Erich G. Schwoerer, Heinrich P. H. Neethling, Pieter H. Stellenbosch University. Faculty of Science. Dept. of Physics. Ultra-short pulses Spectral modulation Spatial light modulator Femtosecond lasers Dissertations -- Physics Theses -- Physics Physics Thesis (MSc)--Stellenbosch University, 2012. ENGLISH 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. AFRIKAANSE 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. 2012-11-28T08:27:05Z 2012-12-12T08:16:18Z 2012-11-28T08:27:05Z 2012-12-12T08:16:18Z 2012-12 Thesis http://hdl.handle.net/10019.1/71883 en_ZA Stellenbosch University xiv, 76 p. : col. ill. application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Ultra-short pulses Spectral modulation Spatial light modulator Femtosecond lasers Dissertations -- Physics Theses -- Physics Physics Mbanda Nsoungui, Gaelle Carine Spectral and temporal modulation and characterization of femtosecond ultra-short laser pulses |
| title | Spectral and temporal modulation and characterization of femtosecond ultra-short laser pulses |
| title_full | Spectral and temporal modulation and characterization of femtosecond ultra-short laser pulses |
| title_fullStr | Spectral and temporal modulation and characterization of femtosecond ultra-short laser pulses |
| title_full_unstemmed | Spectral and temporal modulation and characterization of femtosecond ultra-short laser pulses |
| title_short | Spectral and temporal modulation and characterization of femtosecond ultra-short laser pulses |
| title_sort | spectral and temporal modulation and characterization of femtosecond ultra short laser pulses |
| topic | Ultra-short pulses Spectral modulation Spatial light modulator Femtosecond lasers Dissertations -- Physics Theses -- Physics Physics |
| url | http://hdl.handle.net/10019.1/71883 |
| work_keys_str_mv | AT mbandansounguigaellecarine spectralandtemporalmodulationandcharacterizationoffemtosecondultrashortlaserpulses |