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UV laser modification of transparent materials for photonic applications

dc.contributor.advisorIhlemann, Jürgen Dr.
dc.contributor.authorRichter, Lukas Janos
dc.format.extentXXX Seitende
dc.rightsAttribution-NonCommercial-NoDerivatives 4.0 International*
dc.titleUV laser modification of transparent materials for photonic applicationsde
dc.contributor.refereeHofsäss, Hans Christian Prof. Dr.
dc.subject.gokPhysik (PPN621336750)de
dc.description.abstractengPhotonic applications have experienced strong growth in recent years. Due to increasing digitalization and automation in all areas of life, further growth of photonics is expected in the future. The broad range of photonic applications supports this statement. While photonic applications used to be dominated by telecommunication through optical fibers, the use of photonic processes today is manifold. For example, new light sources have been developed in the form of LEDs (light-emitting diodes) or OLEDs (organic light-emitting diodes). Due to the ability to emit coherent and intense light, lasers (light amplification by stimulated emission of radiation) play a key role as a light source in photonics. In materials processing, for example, lasers enable the structuring or surface modification of materials. Lasers are also used in other areas of photonics. For all these applications, optically transparent materials are indispensable. From the design of a laser up to the optics for beam shaping, transparent materials are required. These are usually glasses, but can also be crystals, ceramics or polymers. In this thesis the modification of transparent materials by lasers is addressed. Glasses and amorphous thin films are structured and functionalized with UV lasers. Single pulse or repetitive laser heating with high spatial resolution enables processes which cannot easily be accomplished by other methods. In the first part of the thesis an introduction to the relevant parts of photonics is provided. The basics of laser materials processing, e. g. laser ablation, are explained in section 1.1. Examples of laser materials processing are introduced and important experimental parameters for these applications are explained. In section 1.2, aspects of laser functionalization of surfaces are discussed. To that end an introduction to relevant physical properties of transparent materials is given. Subsequently an overview of laser-based implantation of metal nanoparticles in glass and laser marking of glass surfaces by several methods is presented. The last part of the introduction, section 1.3, deals with silicon photonics. The band structures of bulk silicon and silicon nanocrystals are explained and the resulting optical properties are discussed. A literature review on this topic is provided. At the end of this chapter, the references of the introduction are provided. In chapter 2, the manuscripts of this cumulative dissertation are presented. In the first manuscript (section 2.1), the generation of a black marking on titanium oxide containing glass by ultraviolet (UV) excimer laser irradiation is presented. The black marking is partly caused by strong scattering by a microstructure on the glass surface. The laser-induced microstructure is accompanied by the formation of a titanium-rich and a silicon-rich phase on the glass surface. A further contribution to the black marking can be attributed to an increased absorption caused by an oxygen reduction of the titanium oxide. By this technique, for example, informative markings such as QR codes can be applied to the glass surface. The process of the fabrication of the marking as well as material analyses are presented. The other two manuscripts deal with silicon photonics. In section 2.2, a method for photoluminescence enhancement of silicon nanocrystals inside a silicon suboxide matrix by laser-based implantation of gold nanoparticles is presented. The results of photoluminescence measurements are discussed with the help of absorption, Raman and scanning electron microscopy measurements. A coupling of the silicon nanocrystals to the plasmonically active gold nanoparticles leads to an enhancement of the photoluminescence. The third manuscript in section 2.3 also deals with the enhancement of photoluminescence of silicon nanocrystals by UV excimer laser-based methods. Laser irradiation of a silicon suboxide surface leads to an enhancement of the photoluminescence. The effects of laser irradiation on the silicon nanocrystals in the silicon suboxide matrix are analyzed by Raman spectroscopy and transmission electron microscopy, among others. Besides a slight photoluminescence enhancement due to structural changes of the silicon nanocrystals, there is an enhancement of the photoluminescence due to a reduction of losses caused by total internal reflection in the highly refractive silicon suboxide layer. A summary and a discussion of the presented results is given in chapter 3. The chapter is divided into the two main topics of laser-based glass marking (section 3.1) and silicon photonics (section 3.2). For this section, the relevant literature is again provided at the end of the
dc.contributor.coRefereeIhlemann, Jürgen Dr.
dc.contributor.thirdRefereeEgner, Alexander Prof. Dr.
dc.contributor.thirdRefereeMoshnyaga, Vasily Prof. Dr.
dc.contributor.thirdRefereeRizzi, Angela Prof. Dr.
dc.contributor.thirdRefereeSeibt, Michael Prof. Dr.
dc.affiliation.instituteFakultät für Physikde
dc.notes.confirmationsentConfirmation sent 2023-04-28T13:45:02de

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