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Výpočet optické odezvy fotonických struktur metodou FDTD
Vozda, Vojtěch ; Veis, Martin (vedoucí práce) ; Richter, Ivan (oponent)
Metoda FDTD vychází z Maxwellových rovnic a v této práci je popsáno, jak tyto diferenciální rovnice upravit pro numerické řešení známé jako Yee algoritmus. Z důvodu získání stabilního řešení je zkoumána závislost časového kroku na prostorovém. Je definována diskrétní Fourierova transformace pomocí které lze získat frekvenčně závislé transmisní a reflexní koeficienty. Naprogramovaná simulace je testována na analyticky řešitelných strukturách i na mírně složitějších systémech jejichž optická odezva byla spočítána jinou simulací. V závěru jsou zmíněny fotonické krystaly a jejich aplikace jako biosenzory. Jedno konkrétní uspořádání fotonického krystalu je v této práci detailně rozebráno (závislost frekvenčního spektra na prostorovém rozlišení, nepřesnostech v geometrii, odlišných sloučeninách v dírách, změnách v geometrii).
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Plasmonic biosensors based on extraordinary optical transmission
Dršata, Martin ; Richter, Ivan (oponent) ; Petráček, Jiří (vedoucí práce)
This diploma thesis deals with rigorous simulations of plasmonic biosensors based on the phenomenon of extraordinary optical transmission. The first part is devoted to the description of the physical phenomena and knowledge, that forms the basis for studying the properties of plasmonic sensors, and the description of the finite-difference time-domain numerical method, that is used for all simulations carried out in this work. Simulation results are listed in the next part of this thesis. Here, the sensitivity, resolution and other characteristics of the chosen type of plasmonic sensor, consisting of an array of circular nanoholes in a thin gold film on the silicon nitride substrate, on a number of its geometrical parameters is investigated. These dependencies are monitored in three different cases, namely a sensor placed in a vacuum, immersed in water and where a thin dielectric layer is present on the gold surface, mimicking the presence of biomolecules immobilized the surface of the sensor.
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Rich Information Optical Biosensor Based on Surface Plasmon Resonance
Dostálek, Jakub ; Homola, Jiří (vedoucí práce) ; Richter, Ivan (oponent) ; Vrbová, Miroslava (oponent)
In the presented thesis, new optical biosensor platform for high-throughput label-free monitoring of biomolecular interactions is reported. This biosensor platform is based on a spectroscopy of surface plasmons on an array of miniature diffraction gratings. Each miniature grating serves as an independent sensing channel and allows for monitoring of optical density changes induced by biomolecular interactions on the grating surface. The presented platform has a potential for monitoring of hundreds of interactions on a single sensor chip. The presented research include theoretical study of surface plasmon resonance on metallic diffraction gratings and the analysis of diffraction grating-based SPR biosensor. In the experimental work, preparation, replication and characterization of diffraction gratings is carried out. A prototype SPR sensor device including an SPR sensor chip with a twodimensional array of sensing channels, fluidic system and SPR chip reader is developed and its main performance characteristics are determined.
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Vedené vlny v periodických strukturách a jejich senzorové aplikace
Vala, Milan ; Homola, Jiří (vedoucí práce) ; Richter, Ivan (oponent)
Práce je uvedena popisem základních vlastností povrchových plazmonů šířících se podél rozhraní kov-dielektrikum a podél struktury s tenkým kovovým filmem obklopeným z obou stran dielektriky se shodným indexem lomu. Je ukázáno, že na symetrické struktuře s tenkou vrstvou kovu lze vybudit dva typy vidů vázáných povrchových plazmonů - long-range povrchový plazmon a short-range povrchový plazmon. Dále je poskytnuta stručná rešerše věnována použití těchto typů povrchových plazmonů v optických senzorech. Je navržena difraktivní vrstevnatá struktura, ve které se vázané vidy povrchových plazmonů excitují na struktuře tvořené tenkým zlatým filmem obklopeným dielektriky s podobnými indexy lomu. S použitím rigorózní integrální metody je difraktivní struktura optimalizována pro aplikaci v senzoru s povrchovými plazmony. Difraktivních struktury s optimálními parametry jsou připraveny a charakterizovány opticky a s použitím mikroskopu atomových sil. V závěru je demonstrována aplikace připravených difraktivních struktur v senzoru s povrchovými plazmony a modulací vlnové délky.
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Modelling of Pulse Propagation in Nonlinear Photonic Structures
Sterkhova, Anna ; Richter, Ivan (oponent) ; Samek, Ota (oponent) ; Petráček, Jiří (vedoucí práce)
The demand for more effective data-storage and faster signal processing is growing with every day. That is why the attention of the scientists is focused on the all-optical devices, which can improve the above mentioned requirements. Microring optical resonators are among the state of art devices, that are under consideration. There is a variety of numerical techniques to simulate processes occurring while the optical signal propagates in the microring resonator structure. They differ in its calculation effectivity, used approximations and possibilities of application. The aim of this work was to develop two simple and practical numerical methods for simulation of pulse propagation in nonlinear waveguide structures. It was also demanded, that opposed to the commonly known and frequently used finite-difference time-domain (FD-TD) method, the newly developed techniques could be easily applicable for the study of nonlinear structures based on microring resonators. That is why developed methods use some approximations, namely the slowly varying envelope approximation. The methods advantage is high speed and low requirements of computational resources. Both techniques are based on observation that waveguide structures that use microring optical resonators can be considered as composed of single waveguides and waveguide couplers. The first numerical technique solves coupled partial differential equations, which describe pulse envelope propagation in the structure. This method uses the “up-wind” scheme, which is suitable for the partial differential equations that describe the wave propagation. The second developed technique is derived from the first one. The difference between methods is in the treatment of the coupling between two waveguides. If in the first method the coupling is considered as the real one, distributed on the given length, in the second method the coupling is considered to be concentrated in one point. Due to this approximation it is possible to integrate the appropriate equations and achieve significant increase of calculation speed. Quasianalytical character of the second method enables also easy identification of different types of steady-state solutions. Due to these properties the second method was used to study spontaneous generation of optical pulses in the structures, consisting of coupled ring resonators. Both methods, which were developed during this work, represent fast and physically illustrative alternatives to the FD-TD, so it can be expected that these methods can play an important role during the research of nonlinear waveguide structures.
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Surface states in photonic crystals
Vojtíšek, Petr ; Richter, I.
Among many unusual and interesting physical properties of photonic crystals (PhC), in recent years, the propagation of surface electromagnetic waves along dielectric PhC boundaries have attracted considerable attention, also in connection to their possible applications. Such surfaces states, produced with the help of specialized defects on PhC boundaries, similarly to surfaces plasmons, are localized surfaces waves and, as such, can be used in various sensing applications. In this contribution, we present our recent studies on numerical modelling of surface states (SS) for all three cases of PhC dimensionality. Simulations of these states were carried out by the use of plane wave expansion (PWE) method via the MIT MPB package.
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Diffractive Optics: Analysis, Design and Fabrication of Diffractive Optical Elements
Fiala, P. ; Matějka, František ; Richter, I. ; Škereň, M.
This contribution presents results obtained in the field of diffractive optics, covering practically all aspects of the analysis, design and realization process of the diffractive optical elements (DOEs). As for the analysis, using the rigorous diffraction methods, we have recently been able to efficiently analyze various diffraction gratings. Concerning the synthesis, several design strategies have been studied and implemented for designing both binary and multi-level phase DOEs. Using the numerically computed designs, E-beam lithography technology has been chosen for fabricating both binary and multi-level phase DOEs, using the BS 600 e-beam lithographic facility at ISI AS CR. Finally, some typical examples of optical reconstructions are presented and discussed.
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