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Modulation of time dispersion of femtosecond laser pulses
Vyhlídka, Štěpán ; Straka, Petr (advisor) ; Ostatnický, Tomáš (referee)
In the presented thesis the topic of femtosecond pulse dispersion and methods of characterizing pulse profile are briefly introduced. Then, a functionality of a spatial light modulator is described. The spatial light modulator was used in an experimental scheme called the pulse shaper, which allowed independent amplitude and phase modulation of pulses. Duration and dispersion of pulses was measured by two methods called MIIPS and PICASO. MIIPS was also used for a reconstruction of a spectral phase of pulses. The autocorrelator was constructed on a design of the Mach-Zehnder interferometer. The duration of the shortest measured pulse (13.3 ± 0.5) fs was retrieved from measured interferometric autocorrelations by PICASO. Furthermore, theoretical dependence of pulse duration on the group delay dispersion was confirmed for pulses shorter than 120 fs. The group velocity dispersion was measured for fused silica windows and for a pair of diffraction gratings in the pulse shaper. Both values confirmed theoretical expectations.
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Light propagation in magnetic materials
Wagenknecht, David ; Ostatnický, Tomáš (advisor) ; Veis, Martin (referee)
Transparent magnetic materials, among the others semiconductors, have recently come to the focus of interest in both basic and applied research because they have great potential in optical applications and they can be used in optical spectroscopy to investigate fundamental physical phenomena. The theoretical calculations introduce that these materials have some extraordinary properties like asymmetric reflectance when light impact the sample from the opposite angles. In this bachelor thesis, transfer matrix formalism is derived based on Maxwell equations, taking into account special form of effective permittivity. The reflection coefficient for one layer demonstrates, that the asymmetric reflectance appears for transversal- magnetic polarization of light and transversal magnetization in the studied material. The derived formulae are used to calculate the difference in reflectivities for the waves impacting the structure from opposite angles. Ga1−xMnxAs with different concentrations of manganese is assumed to be the essential transparent magnetic layer in the sample. 1
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