National Repository of Grey Literature 24 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Design of metasurfaces for advanced optical elements
Březina, Tomáš ; Kvapil, Michal (referee) ; Hrtoň, Martin (advisor)
Metasurfaces represent an intriguing class of materials with a wide range of promising applications, one of them being advanced planar optical elements for industrial production and imaging. The main goal of this thesis is to design such an optical element, namely a beam-shaper consisting of dielectric anostructures in HCTA (high constrast transmitarray) arrangement. The first part of this work introduces a simplified theoretical model of the optical response of building blocks that facilitates understanding of the basic functional mechanism behind the phase metasurfaces. To quantify the optical response of dielectric building blocks with enough precision, numerical FDTD simulations were employed. As a result, a database compatible with lithographic fabrication procedures was created. To find the phase distribution ensuring the desired beam-shaping function, two approaches were investigated and implemented: the semi-analytical method of geometric transformation and the iterative Gerchberg-Saxton algorithm. The final output of this work is then the distribution of building blocks within the metasurface that imprints into the impinging beam the previously calculated phase profile.
Hybrid plasmonic waveguides
Kulič, Martin ; Gryga, Michal (referee) ; Kvapil, Michal (advisor)
Optical waveguides have been used for information transfer for many years. Their use in modern applications is however severely limited by the diffraction limit. Plasmonic waveguides, on the other hand, offer significant miniaturisation at the cost of large attentuation. Hybrid plasmonic waveguides offer a solution benefitting from both of these approaches, i.e. significant miniaturisation with fairly large propagation lengths. These structures have not been studied enough for their widespread use yet. This thesis focuses on current applications of hybrid waveguides and outlines the analytical a numerical methods of their study. The second part of this thesis is aimed at simulation and optimization of selected geometries with regards to propagation length and mode area. The influence of basic dimensions and material selection is studied. Detailed optimization of these structure allows their widespread use in modern scientific and technological applications.
Optical characterization of perovskite nanostructures
Urban, Jakub ; Kvapil, Michal (referee) ; Dvořák, Petr (advisor)
The present bachelor's thesis focuses on the optical characterization of CsPbBr3 nanocrystals ranking among the group of materials called perovskites which are remarkable for their high photoluminescence (PL) quantum yield. An algorithm for a correlation of experimental data measured by PL mapping with morphological and topological properties obtained by using Scanning Electron Microscopy and Atomic Force Microscopy has been developed which clears the way for a particular crystal detection and their spectrum analysis. Specifically, crystals the shape of which can be approximated by a cuboid have been detected and the volume dependence of the centre of mass of their PL, which is proportional to V^(-2/3) as predicted by the theorethical model, has been discovered. The measurement of PL dependency on temperatures ranging from 40 to 60 °C has also been conducted and in this temperature interval linear dependence of the full width at half maximum of their PL spectral line that rises with rising temperature has been confirmed. On the contrary, the centre of mass of PL has been found to be temperature independent.
Application of two-dimensional layers of transition metal dichalcogenides in plasmonics
Kocourková, Monika ; Hrtoň, Martin (referee) ; Kvapil, Michal (advisor)
Two-dimensional layers of transition metal dichalcogenides are materials with some very intriguing properties, such as the existence of room-temperature stable excitons in visible and near-IR spectrum. Their integration into plasmonic systems allows enhancement of their photoluminescence, absorption, etc., which can be used in various applications. This thesis begins with an overview of the basic terminology and fundametal principles behind these materials and hybrid systems. The theoretical part then focuses on some plasmon-excitonic system examples. Practical part of this thesis is aimed at simulating and optimizing two different plasmon-excitonic systems using monolayer molybdenum disulphide and tungsten disulphide.
2D near-field digital holography
Klok, Pavel ; Kvapil, Michal (referee) ; Dvořák, Petr (advisor)
This bachelor’s thesis presents an experimental study of the phase distribution of the surface plasmon polaritons (SPPs) interference by using an aperture-type Scanning Near-field Optical Microscope (a-SNOM). Interference patterns caused by the excitation of SPPs waves on variously arranged grooves were detected and compared with FDTD simulations. Using the 2D Near-field Phase-Shifting Digital Holography (NPDH) method, phase distribution in individual interference nanostructures was imaged and later compared to the results obtained from FDTD simulations.
Numerical optimization of absorption of mid-infrared plasmonic structures
Kulič, Martin ; Křápek, Vlastimil (referee) ; Kvapil, Michal (advisor)
Plasmonic nanostructures have a long and rich history in spectroscopy and sensing. First, we look at the history and applications of plasmonic structures and we discuss the parameters that influence the enhancement of various methods. Then the influence of plasmonic nanostructures on energy absorption in a thin layer of silicon oxide, silicon nitride and silicon-rich oxynitride of varying thickness is probed using Lumerical FDTD Solutions software. The last part of this thesis focuses on numerical demonstration of application of plasmonic antennas in spectroscopy.
Interaction between SNOM tip and near-field
Krpenský, Jan ; Kvapil, Michal (referee) ; Dvořák, Petr (advisor)
Interaction between a probe for scanning near-field optical microscopy (SNOM) and near electromagnetic field is a fundamental problem, with its solution being a necessary condition for the correct interpretation of experimental data. This bachelor's thesis is aiming to thoroughly describe this problem and by precise manufacturing of our own SNOM probes help to reach solution of this problem. For this purpose, the detection of near-field generated by interference of surface plasmon polaritons (SPP) on square shape nanostructures is being used. This study has proven the dependence of SNOM probe sensitivity to near-field components on the size of a SNOM aperture.
Multidisciplinary access in community care of mentally diseased
Kvapil, Michal ; Válková, Monika (advisor) ; Palánová, Tereza (referee)
The diploma is about the topic of multidisciplinarity in community care of people with mentally illness. I chose this topic because I meet clients who have lived for various periods of time knowing that they suffer of mental illness. Over time, I began deeply perceive how mental illnesses affect all areas of client's lives. In the modern sense of community-based psychiatric services, multidisciplinary cooperation should become a provider of more comprehensive, better quality and more effective services for people with mental illness who require health care, but also social care that facilitates inclusion in the society of people who suffer of mental illness. Multidisciplinary collaboration is an interdisciplinary collaboration in social and health services, illustrates different theories that use various terminologies. The collaboration of experts from different disciplines, in addition to the term multidisciplinary, can be referred also as interdisciplinary or intersectoral. Another reason for choosing the topic of the thesis is the increas of discussions and even practical steps within the Strategy of Psychiatric Reform in the Czech Republic. An integral part of the thesis is an introduction to mental health issues, it's history and current planned transformation, which is a priority within the...
Metallic nanostructures with three-dimensional topography for plasmonics
Rovenská, Katarína ; Kvapil, Michal (referee) ; Ligmajer, Filip (advisor)
Due to high concentration of free electrons, metallic nanostructures can support plasmonic resonances. The spectral shape of plasmonic resonances may be tuned by many factors and because of it, the field of their application, given by their capability of focusing light under the diffraction limit, broadens. This thesis deals with fabrication of gold nanostructures by electron beam litography on top of a silicon substrate. The topography of the substrate is subsequentially modified by wet anistropic etching. A part of this thesis also briefly reviews methods for fabrication of nanostructures with planar or three-dimensional topography. Using the infrared spectroscopy, this thesis further analyzes the effect of size, shape, spacing of the nanostructures, and also the substrate topography on the optical response of the fabricated nanostructures. The outcomes of this thesis verify previously described tendencies of spectral relations between optical properties and named parameters in the mid-infrared region.
Fabrication and characterization of plasmonic nanostructures
Bačo, Ondřej ; Kvapil, Michal (referee) ; Dvořák, Petr (advisor)
This bachelor thesis deals with fabrication and characterization of plasmonic nanostructures. Graphene on a doped silicon substrate with a 285 nm thick layer of silicon dioxide was used for fabrication of these structures. Graphene ribbons with width in the order of hundreds of nanometers were prepared using electron beam lithography (EBL) and reactive ion etching (RIE). Steps in fabrication process were monitored utilizing optical and atomic force microscopy (AFM). Prepared graphene nanostructures were characterized with scanning electron microscope (SEM) and Fourier transform infrared spectrometer (FTIR).

National Repository of Grey Literature : 24 records found   1 - 10nextend  jump to record:
See also: similar author names
4 KVAPIL, Martin
4 Kvapil, Martin
2 Kvapil, Matouš
2 Kvapil, Matěj
2 Kvapil, Mikuláš
3 Kvapil, Milan
Interested in being notified about new results for this query?
Subscribe to the RSS feed.