Author: LUKAS RAMALIS
Dissertation title: Formation of sculptured thin films on crystalline substrates and their investigation in laser systems
Fields of science: Material engineering T008
Scientific supervisor: dr. Tomas Tolenis
Defence of the dissertation: 28 May 2025
SUMMARY: Optical elements are one of the most important components in a laser system, which usually limit the output laser radiation power due to the relatively low induced damage threshold. In order to improve the resistance to laser radiation, optical elements are modified in various ways, including layer material engineering by forming a multilayer structure. This dissertation studies optical elements formed on the basis of sculptural coatings, which are characterized by very high porosity. The main goal of the dissertation is to stabilize the optical properties of these nanostructured layers and expand the application possibilities by forming optical elements directly on laser crystals. The first part of the dissertation presents studies of the damage threshold of single-layer coatings of different materials formed using the sliding angle evaporation method. Having chosen the most resistant material - silicon dioxide, a Bragg mirror is formed using only one material. This part studies the degradation of the resistance of sculptural coatings to laser radiation depending on environmental conditions. In order to reduce degradation, local laser annealing was applied, which increases the resistance of Breg mirrors to laser radiation. The last part of the dissertation presents a new method for forming total internal reflection elements with nanostructured coatings directly on YAG laser crystals. The research contributes to the development of advanced optical components and helps to better understand the change in the properties of sculptural coatings and their stabilization capabilities.