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Spectroscopy of semiconductors with ultra-high time resolution
Hanák, Martin ; Trojánek, František (advisor) ; Kozák, Martin (referee)
This thesis is aimed at building and optimization of a new experiment setup for measuring time-resolved transmittance using a pump-probe method. Test measurements were then conducted on a sample of SiV centers in diamond. The theoretical part contains a general description of luminescence of color centers. It then specifically focuses on SiV centers in diamond and describes their structure, electronic and spectral properties in detail. The description of our setup and its optimization is given at the beginning of the experimental part. The dependencies of differential transmittance of SiV centers in diamond on excitation intensity and wavelength were measured and the lifetime of SiV centers was then determined from our measurement results. 1
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Laser spectroscopy of crystalline and nanocrystalline diamond
Zukerstein, Martin ; Trojánek, František (advisor)
The aim of this thesis is a study of NV centres in crystalline and nanocrystalline diamond by laser spectroscopy methods. In the theoretical part we discuss the laser spectroscopy methods, the studied material - diamond and the NV colour centres. In the experimental part we discuss the influence of nanoparticle size on luminescence spectra. We measure the luminescence of samples at room and also at low temperatures depending on the intensity and wavelength of the excitation. We study the photo-conversion of negatively charged state of NV centres to the neutral in detail. We make the time resolved measurements of the luminescence on streak camera for characterization the dynamical properties of the studied samples. The result is the comparison of lifetimes of the states in NV centres in selected samples.
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Time-resolved spectroscopy of wide-bandgap semiconductors
Martínek, Miroslav ; Trojánek, František (advisor)
In this thesis experimental samples of multiple quantum wells in the InGaN/GaN structures will be compared using methods of laser spectroscopy. In particular, the optical properties of the samples will be investigated. The samples were prepared under different conditions; therefore one of the aims is to compare them. The knowledge of the influence of preparation enables utilization not only for fundamental research, but also for the construction of radiation sources or scintillation detectors. Measurements of absorption and photoluminescence will be carried out and their dynamic properties will be measured as well. There will be examined the effect of different excitation power and different excitation wavelength on the intensity of photoluminescence. From dynamic properties there will be examined the effect of different excitation wavelength on the lifetime of the absorption and how does temperature influence the lifetime of the photoluminescence. Individual quantities will be compared amongst samples and their suitability for further applications will be discussed.
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Spectroscopy of semiconductors with ultra-high time resolution
Hanák, Martin ; Trojánek, František (advisor) ; Kozák, Martin (referee)
This thesis is aimed at building and optimization of a new experiment setup for measuring time-resolved transmittance using a pump-probe method. Test measurements were then conducted on a sample of SiV centers in diamond. The theoretical part contains a general description of luminescence of color centers. It then specifically focuses on SiV centers in diamond and describes their structure, electronic and spectral properties in detail. The description of our setup and its optimization is given at the beginning of the experimental part. The dependencies of differential transmittance of SiV centers in diamond on excitation intensity and wavelength were measured and the lifetime of SiV centers was then determined from our measurement results. 1
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SMV-2020-55: ADJ3 standard
Hrabina, Jan ; Jelínek, Michal ; Čížek, Martin ; Číp, Ondřej
The contractual research was oriented towards works on ADJ3-CESNET laser standard:\n- analysis and measurement of actual parameters of the system \n- reduction of electric noise (control system) \n- optical polarization stabilization (beat-note measurements) \n- upgrading of control SW \n- PID control optimalization, verification tests of the system
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Combination of laser spectroscopy methods for chemical analysis
Holub, Daniel ; Novotný, Karel (referee) ; Pořízka, Pavel (advisor)
The topic of this Master’s thesis is combination of laser spectroscopic methods. LIBS and Raman spectroscopy were chosen for the combination. This combination is applied to plastic identification and separation as a mean to automate sorting of plastic waste. Data handling was done via different methods of computer learning algorithms scripted in R language. Plastic sorting accuracy over 90 % was reached thanks to the combination of chosen methods. This work also addresses some issues implied by combination of two different methods.
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SMV-2019-73: Optical frequency references
Lazar, Josef
Development of optical frequency references with multipath configuration, quartz glass windows, perpendicular to cell axis, plan-parallel, useful aperture 32 mm, resp. 36 mm, cold finger in the center, windows with optical quality surfaces /10 @ 633 nm for the clear aperture with antireflection coating on both sides, residual reflectivity < 0.1% at 532 nm wavelength, high reflection coatings on outer surfaces at ¾ of horizontal diameter of the useful aperture. Filling: Iodine – 127I.
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SMV-2019-72: Optical frequency references
Lazar, Josef
Development of optical frequency references of quartz glass with optical quality windows, useful aperture 24 mm (diameter of the external and internal AR coatings for the 1550 nm wavelength), length 250 mm, filling pin (with transition from quartz glass to pyrex) in the center, windows with surfaces flatness λ/10 @ 633 nm for the clear aperture, filling: Isotopically pure Acetylene.
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