|
|
Nonlinear phenomena in optical fibers
Burian, Radek ; Horváth, Tomáš (referee) ; Münster, Petr (advisor)
The subject of this thesis is to describe nonlinear phenomena in the optic fiber. The theoretical part describes a principle of transmission in optical fibers. Optics modules, fibers and their parameters are described marginally. Except nonlinear phenomena, there is also described linear phenomena such as attenuation, dispersion, scattering. In terms of nonlinear phenomena there is described second order phenomena such as Second harmonic generation (SHG), Sum and difference harmonic generation (SFG and DFG) and third order phenomena, such as Kerr effect, Third harmonic generation (THG), Four-wave mixing (FWM) and Cross phase modulation (XPM). There are also described nonlinear scattering, such as Raman´s and Brillouin´s scattering. The Four-wave mixing is simulated in the first half of the practical part. Four-wave mixing occurs in DWMD systems, where can invoke cross-talks between channels. In the second half of the practical part is measured this nonlinear phenomenon. The aim of the measurement is to understand the behaviour of the FWM and find the way how to eliminate its power. The Four-wave mixing measurement is based on the simulation. Second measurement is designed for Brillouin scattering. The conclusion from simulated and laboratory part from both measurements are compared with theoretical knowledge.
|
|
|
Design of optical fiber sensor for vibration detection
Janoušek, Adam ; Münster, Petr (referee) ; Dejdar, Petr (advisor)
The master theses deals with a detailed analysis of optical fiber sensors. Specifically, there are discussed optical fibers, various types of sensors and realization optical fiber senzor and senzor system that has been optimized and processed data in real time. In master theses also describes the LabView programming enviroment and uses components, including the entire sensor systém of a sensors system that sends measured data
|
|
|
Mathematical analysis and simulation of optical fiber transmission parameters
Smrž, Jan ; Šporik, Jan (referee) ; Tejkal, Vladimír (advisor)
This thesis deals with the transmission of optical fibers, their properties and method of calculation. The paper presents different types of fiber types and standards. There is a description of the connection of optical fibers with different methods, including variations joints. Further side effects are broken fibers, dispersion and attenuation. The last part is devoted to describing the program, which was part of this work. The program is used to calculate the transmission parameters of optical fibers and optical losses incurred in connection.
|
|
|
The issue of the use of carbon nanotubes in cement composites
Pacltová, Klára ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
The bachelor thesis deals with the analysis of the efficiency of carbon nanoparticles in cement composites. The theoretical part of the bachelor thesis is focused on the research of information about carbon nanotubes and their influence on cement composites. The practical part follows the research of the theoretical part, where is verified the effectiveness of carbon nanotubes in cement composites at different dosages.
|
|
|
Static and dynamic properties of nanostructured magnetic materials
Vaňatka, Marek ; Wintz, Sebastian (referee) ; Dijken, Sebastiaan van (referee) ; Urbánek, Michal (advisor)
Magnetické materiály a z nich vyrobené nanostruktury jsou v průběhu posledních let studovány pro jejich aplikace v např. záznamových médiích a logických obvodech. Tato práce navazuje na náš předchozí výzkum tohoto oboru s hlavním zaměřením na statické a dynamické vlastnosti nanostrukturovaných magnetických materiálů, jako například NiFe, CoFeB a YIG. Práce začíná teoretickým úvodem s popisem mikromagnetických systémů, dynamiky magnetických vortexů, feromagnetické rezonance (FMR) a spinových vln včetně jejich disperzních vlastností. Následuje popis použitých experimentálních metod a první experimentální část zabývající se nukleačním procesem magnetického vortexu, jinými slovy procesem transformace ze saturovaného stavu do spinové konfigurace magnetického vortexu v průběhu snižování magnetického pole. Jsou použity mikroskopické metody zobrazující magnetickou strukturu materiálu, jmenovitě Lorentzova transmisní elektronová mikroskopie a rentgenová transmisní mikroskopie. Výsledky jsou poté korelovány s měřením elektrické odezvy pomocí jevu anizotropní magnetorezistence. Výhodou elektrických měření je, že plně elektrická detekce dovoluje použití tohoto systému v uzavřených systémech integrovaných obvodů. Výsledky oblasti nukleací magnetických vortexů ukazují, že při tomto procesu prochází magnetizace v nano- a mikrometrových magnetických discích několika fázemi s růsnými typy spinových konfigurací nazvaných nukleační stavy. Dále je představeno měření magnetických materiálů pomocí vektorového síťového analyzátoru (VNA), což je aplikováno na měření resonance magnetických vortexů (určení gyrotropické frekvence a měření vysokofrekvenčních módů), feromagnetické rezonance tenkých vrstev (získání základních magnetických materiálových parametrů) a spektroskopii spinových vln. Právě spektroskopie spinových vlna je rozvinuta za účelem měření disperzních relací tenkých magnetických vrstev, což je základní charakteristika, jejíž znalost je důležitá v návrhu aplikací. Nakonec je představeno anténní zařízení, díky kterému lze oddělit magnetické buzení od vzorku samotného bez nutnosti absolvovat proces elektronové litorafie, což je zapotřebí v klasickém přístupu antény na vzorku a kontaktování vysokofrekvenční sondou. Toto zařízení se skládá ze skleněného kantilívru, na kterém je vyrobena budící anténa, konektoru a spojovacího prvku v podobě plošného spoje. Celé zařízení je díky umístění na x-y-z stolek s náklonem pozicovatelné a lze tedy měřit v jakémkoliv místě vzorku. Umístění antény na sklo umožňuje navigaci pomocí mikroskopu a optické měření, např. metodou Brillouinova světelného rozptylu (BLS) nebo Kerrova jevu.
|
|
|
Utilization of Nanofibres in the Traditional Ceramics Body
Sedláček, Daniel ; Stančík,, Hynek (referee) ; Sokolář, Radomír (advisor)
This thesis summarizes the current knowledge about ceramic composites with nanofibers. So far, most research focused on the reinforcement of hi-tech ceramics, such as carbides and nitrides, however, this traditional ceramics left behind. Due to the improving the efficiency of production of nanofibers and thus a drop in prices, companies consider their use even in a cheaper ceramic materials. Reinforcement of traditional ceramic shard could theoretically improve many characteristics, but there are absolute minimum of practical researches.
|
|
|
Optical fibre factors that limit thetransmission capaity of optical lines
Rouča, Tomáš ; Tejkal, Vladimír (referee) ; Reichert, Pavel (advisor)
Bachelor´s thesis more closely specifies effects of attenuation and dispersion of optical fibers in connection with influencing transmitted signal bandwidth and data transfer capacity. It also examines the influences acting on the optical signal passes through an optical fiber and the mechanism that lead to the attenuation or complete suppression of the signal. The first chapter describes in detail the transmission environment in terms of optical fiber attenuation characteristics of the signal loss caused by rough handling of the optical fiber, manufacturing and material specifications, resulting in scattering or absorption of the transmitted signal. Also, whether the description of fiber dispersion, resulting in the shrinking spectrum of transmitted signal and thus the amount of data at a certain point in time transfer to a defined distance. The second chapter analyzes the effects of attenuation and dispersion in fiber optic transmission capacity currently used in presently optic cables, mechanical couplings, connectors and active components. By mentioning a few examples of real transmission lines with regard to the spectral transmission characteristics that these systems require. This study also includes protocols used to transfer information using xWDM systems. The third chapter deals with modern methods to establish a number of optical signals into a single transmission fiber. Particular attention is devoted to describing the principle of association of the channels in the optical frequencies xWDM, since this method does not currently have a standard solution of information transmission optical fiber for its use significantly more bandwidth, longer distances while maintaining vaulted speed transmission and the possibility of flexible extension without laying new cables and reduce the cost of building transmission lines. The last chapter focuses on describing the implementation of a mathematical model to the spectral characteristics of optical fibers.
|
|
|
Evaluation of the rail pad stiffness
Šardická, Klára ; Pazdera, Luboš (referee) ; Smutný, Jaroslav (advisor)
Rail pads are part of baseplate and baseplateless fastening system. It is a flexible element that is used primarily to reduce the negative effects of dynamic stress, reduce noise and vibration. This thesis deals with laboratory measurement of low-frequency dynamic stiffness at 5 Hz, static stiffness according to ČSN and static stiffness according to OTP of rail pads. The aim is to carry out and evaluate the measurements of samples supplied by different manufacturers and to compare them according to the variance of the resulting stiffnesses. Evaluate the stiffness of used rubber pads and compare with the results of new samples. Further, this thesis deals with the factors that the measurement itself and its results could influence.
|
|
|
Evaluation of Selected Software Tools for Modeling the Leakage of Hazardous Substances in Accidents in the Chemical Industry
Hrušková, Veronika ; Martincová, Jana Victoria (referee) ; Adamec, Vladimír (advisor)
The thesis is aimed at the modeling of releases of hazardous substances to the designated software tools. The work consists of three parts. The first part is theoretical, which deals with hazardous substances and their legislation, accidents in industry, physical models of leakage and dispersion of hazardous substances and factors influencing their spread in the air and finally software tools. The second part, experimental, describes some software tools and their subsequent modeling. The third part is devoted to the results of modeling and analysis of selected software tools. The aim of the thesis is to analyze selected software tools for modeling the release of hazardous substances, to compare their explanatory power and potential use.
|
|
|
The Optical Fibre Dispersion Effects on Multiplex Transmission Systems
Kyselák, Martin ; Filka, Miloslav (advisor)
This doctoral thesis deals with present trend to turn up the bit rate of the optical fibres making use of wavelenght multiplex systems. There are new theoretical and practical problems caused by the new technologies. Except the known modal dispersion there exist problems caused by chromatical and polarization mode dispersion. In the opening of the thesis the known effects, which influence the payload signal, are introduced. The polarization mode dispersion has the main attention. Within the scope of this thesis there has been programmed the statistical calculator which can analyses the measured values of differential group delay by Monte Carlo calculation. Next meaningful output is the designating application of the optical routes. It is possible to mathematicaly unambiguously define the polarization mode dispersion by Jones, Stokes and Poynting vectors. This complicated calculations are mechanized and in the simulation application make possible to simulate the signification of the PMD influence at different input parameters. The thesis includes the study of the PMD modulation format impact with the results of simulations and confrontation with other scientists results. The significant output are the final practical results examinations, which can be implemented thanks to the possibility of using the FTB-5500B measuring device.
|
guest ::
