National Repository of Grey Literature 2 records found  Search took 0.00 seconds. 
Preparation of LiNbO3 nanostructures and their characterization
Pikna, Štěpán ; Jelínek, Michal (referee) ; Dvořák, Petr (advisor)
This master thesis is focused on the deposition of LiNbO3 on c-cut Al2O3 substrate. This material exhibits an electro-optic effect, which refers to the change in the refractive index upon the application of an external voltage, and it has extensive applications in electro-optic modulators. Currently, there is significant interest in miniaturizing these devices for use in the fields of meta-optics and photonics, where its transparency is also advantageous. The first part of this thesis is dedicated to a review of the electro-optic effect and its application in optical metasurfaces. Subsequently, the review addresses the pulsed laser deposition of LiNbO3. The practical part begins with the optimization of target fabrication from LiNbO3 wafers using a laser cutter. Following this, the measurement of the electro-optic effect from a monocrystalline LiNbO3 wafer is discussed. The final section is devoted to the deposition of this material onto a sapphire substrate and further analysis using SPM, XPS, XRD, and SEM. Monocrystalline growth of 30 nm grains was observed, and the physical dependencies of the growth was studied.
Fabrication and characterization of advanced microfluidic chips
Vejrosta, Jakub ; Novotný,, Jakub (referee) ; Plichta, Tomáš (advisor)
This diploma thesis deals with the design, fabrication and verification of microfluidic chips that can be used to sort particles using surface acoustic and standing surface acoustic waves. The sorting function of this chip is based on the piezoelectric properties of the substrate. For this reason, lithium niobate was selected as the substrate. The acoustic waves are generated by interdigital transducers placed directly on the surface of the substrate, which were fabricated by metal layer evaporation, optical lithography and reactive ion beam etching techniques. The microfluidic channels were made from a biocompatible polymer, polydimethylsiloxane, and subsequently bonded to the substrate with the interdigital transducers already prepared. The correctness of fabrication and assembly of the optimized microfluidic chips was subsequently verified experimentally by sorting polystyrene particles of different diameters. Another application of these chips was the preparation of oriented structures of the bacterium Cupriavidus necator H16 using surface acoustic waves.

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