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Strong Coupling in Plasmonic Structurers
Gryga, Michal ; Brzobohatý, Oto (referee) ; Šikola, Tomáš (advisor)
This diploma thesis deals with numerical simulations of the optical response of plasmonic infrared antennas placed on silicon substrates with thin film of silicon dioxide and subsequently with fitting of scattering spectra by model of coupled harmonic oscillators. In this work, we study an influence of length of antennas on the strength of coupling of localized surface plasmons in the antennas with phonons in silicon dioxide film. Also, the influence of silicon dioxide film thickness on this coupling is investigated.
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A Brief Design of Optical Resonators
Hubík, Daniel ; Nešpor, Dušan (referee) ; Kadlec, Radim (advisor)
This bachelor thesis is focused on analysis of split-ring resonators in THz region. Simulations were made by finite elements method and by finite-difference time-domain method. At first we created a resonating structure that works in GHz region. Then we were observing a dependence of movement of resonant frequency on the size of resonator. In the final chapter we assigned frequency dependent values of permitivity to such structure. As the result we simulated working resonator at frequency 500THz. All simulations have been made in program HFSS ANSYS and Lumerical FDTD Solutions.
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Modelling of Local Plasmon Resonances
Dvořák, Petr ; Dub, Petr (referee) ; Kalousek, Radek (advisor)
This Bachelor’s thesis is dedicated to plasmon resonance systems. The first part deals with the analytical and numerical description of behaviour of the surface plasmon polaritons in the edge proximity of metal antennas. The second part is devoted to the simulations of dispersion of light on Ga cap deposited on Si substrate. Possibilities of measurements of the resonance with the SNOM method is mentioned at the end.
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Optical response of infrared plasmonic antennas in presence of silicon dioxide thin film
Biolek, Vladimír ; Dubroka, Adam (referee) ; Kvapil, Michal (advisor)
The diploma thesis deals with the optical response of resonant infrared antennas on silicon dioxide thin film. At first, theory of electromagnetism at metal/dielectric interfaces is described. In the next part, experimental and numerical methods used in the thesis are described and strong coupling between two systems is explained. In the final part of the thesis, the optical response of resonant infrared antennas on a silicon dioxide thin film is studied by Fourier transform Infrared Spectroscopy and FDTD simulations which both show the strong coupling between localized plasmons and phonons in silicon dioxide.
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Numerical EM analysis of semi-composite model of EV55 aircraft
Krutílek, David ; Olivová,, Jana (referee) ; Kadlec, Petr (advisor)
This thesis deals with problems of electromagnetic fields' simulations in the aerospace industry. Electromagnetic effects of the external environment that maybe met during a standard flight (high-intensity radiated fields and lightning strike) are described hereinafter with a reference to their simulations on a digital mockup. A brief summary of the nowadays methods and solvers in computational electromagnetics to be practically used for the modeling and simulations in this field is elaborated as a base for the following parts of the diploma task. The next goal was to create a convenient model simulation of the researched object semi-composite aircraft EV55, on which chosen computing methods will be compared with the results of the real measuring.
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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.
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Loudspeaker System for Reproduction of Low Frequencies with Directional Radiation
Skvaril, Šimon ; Husník, Libor (referee) ; Schimmel, Jiří (advisor)
Final product of this work is design of speaker baffle which will have directional radiation at low frequencies. In the course of the work, propagation of sound waves and their beaviour at obstacles are described. The computational method FDTD and the K-wave toolkit for MATLAB, which uses this method, are described. In MATLAB a virtual model of speaker baffle is created and proposed solution is verified. Next step is creation of scaled model of speaker baffle on which agreement of theoretical computations with real-world measurment is verified. Final step is creation of prototype of speaker baffle,, whose parameters are measured, including polar response.
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Advanced simulations of photonic structures by FDTD method
Vozda, Vojtěch ; Veis, Martin (advisor)
Finite-Difference Time-Domain method (FDTD) is based on numerical solution of Maxwell's equations, nowadays widely used for simulating optical response of photonic structures. This paper provides brief introduction to the FDTD method and several important extensions which make the basic code much more versatile. In order to broaden analysis of photonic structures, transfer matrix method (TMM) is also involved. The code is firstly tested using simple model structures which optical response might be compared with different numerical or even analytical approaches. Debugged code is used to improve photonic crystals for enhanced sensitivity of biosensing devices based on refractive index changes of sensed medium. Last but not the least, properties (sensitivity and Q-factor of resonant peak) of holey waveguide are investigated in one-, two- and three-dimensional simulation. It is shown here, that even this simple structure may compete with complex photonic crystals in the field of biosensors. Powered by TCPDF (www.tcpdf.org)
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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.
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Numerical simulations of optical response of nanostructures using FDTD method
Novák, Ondřej ; Veis, Martin (advisor) ; Vozda, Vojtěch (referee)
Title: Numerical simulations of optical response of nanostructures using FDTD method Author: Ondřej Novák Institute: Institute of Physics of Charles University Supervisor: RNDr. Martin Veis, Ph.D., Institute of Physics of Charles University Abstract: Abstract: The aim of this thesis is to develope an efficient algorythm to compute optical response of nanostructures and to equip it with usefull tools for further data processing. Considered problem is reduced to two dimensions and the method used is the Finite Difference Time Domain (FDTD). This method operates on finite grid called Yee grid and is often called Yee algorithm. En extra emphasis is given on optimalization of the algorithm and writing the computer code efficiently. Evolution equations are written in tensor form and the core algorithm is moved to graphic card using CUDA. Various boundary conditions are introduced to reduce reflections on the edge of the grid. Representation of a real object on the Yee-grid is discussed with introduction of several smoothing methods to improve the shape convergence of simulated object. Useful post- processing methods are introduced - discrete Fourier transform, from which the frequency response of simulated object can be computed and a way to compute the far field from the near field. Finaly, there is an attempt...
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