Lūžio rodiklio modifikavimas stikluose ir kristaluose veikiant ultratrumpaisiais lazerio impulsais /

The study on refractive index modification of transparent materials with ultrashort laser pulses is presented in this dissertation. Based on experimental data it was demonstrated, that using ultrashort pulses, generated with Yb:KGW laser system, it is possible to produce modified refractive index zones in the fused silica glass, that possess birefringence. This effect is caused by nanogratings that form in the bulk of the material. Homogeneity of the modified zones is determined by the accumulation effects, mainly the number of pulses that affect each area. Refractive index variations can be created also in crystalline material such as lithium niobate. Depending on the writing pulse parameters different types of modifications can be created: permanent modification that is caused by crystal amorphization and non-stable modifications that originate from the photorefractive properties of the crystal. Latter modifications can be used for three-dimensional, rewritable data recording. Highly efficient photonic elements, such as volume Bragg gratings, recorded in fused silica and lithium niobate crystal are demonstrated. The technique allowing the evaluation of refractive index change applying Bragg gratings is described. Also modification influence on nonlinear processes that appear in fused silica such as filament formation and supercontinuum generation is experimentally investigated.

Grantor dc:publisher

Institutional Repository of Vilnius University

Year dc:date

2011

Author dc:creator

• Paipulas, Domas,

• femtosecond laser micromachining ; refractive index modifications ; Bragg grating ; fused silica ; lithium niobate

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

lit

Repository record dc:identifier

https://repository.vu.lt/VU:ELABAETD2004292&prefLang=en_US

OAI identifier oai:identifier

oai:vu.lt:elaba:2004292