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Generation of carrier-envelope-stable few-cycle pulses in the mid-infrared spectral region
Peterka, Pavel ; Kozák, Martin (advisor) ; Žídek, Karel (referee)
In this thesis we present the realization of a source of 1.5-cycle carrier-envelope phase stable laser pulses in the mid-infrared spectral region. We used ytterbium laser system generating 1 µm pulses as a pump of setup, where the beam is split into several parts and interact in nonlinear optical media. 2 µJ pulses with duration 18 fs at 50 kHz repe- tition rate are produced. By spectral broadening in crystal GGG, 9,9 fs pulses can be achieved. The mid-IR pulses was characterized by third harmonics generation frequency resolved optical gating in the interferometric configuration. Fourier filtering of the mea- sured interferogram allows for the complete reconstruction of amplitude and phase of the ultrashort pulses generated by our setup. The pulses will in future serve for experimental investigation of ultrafast strong-field phenomena in solids. 1
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Nonlinear optical frequency conversion of few-cycle laser pulses
Koutenský, Petr ; Kozák, Martin (advisor) ; Galář, Pavel (referee)
Title: Nonlinear optical frequency conversion of few-cycle laser pulses Author: Petr Koutenský Department: Department of Chemical Physics and Optics Supervisor: RNDr. Martin Kozák, Ph.D., Department of Chemical Physics and Optics Abstract: The goal of the thesis was to achieve generation of second harmonic frequency from ultrashort laser pulses with central wavelength of 780 nm and to compress the generated pulses to the shortest possible time duration. We have studied and optimized the efficiency of second harmonic frequency generation from wide spectrum laser, which generates ultrashort pulses with a duration of few femtoseconds. Firstly we have developed and optimized the experimental setup for the highest power output of the generated second harmonic frequency pulses. Afterwards we measured the duration of the generated pulses using nonlinear optical cross- correlation with the pulses at the fundamental frequency generated by the laser. Cross- correlation was obtained from sum frequency generation in a thin nonlinear BBO crystal. The pulses at the second harmonic frequency were compressed to a duration of 13 femtoseconds by combining wide spectrum mirrors with negative dispersion of group velocities and thin fused silica wedges. These ultrashort pulses will be used in experiments with high time...
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Preparation and study of novel crystalline materials for nonlinear optics based on nitrogen-containing heterocycles
Kloda, Matouš ; Němec, Ivan (advisor) ; Schwendt, Peter (referee) ; Holubová, Jana (referee)
The presented Ph.D. thesis is aimed at the preparation and characterisation of novel crystalline materials with application potential in nonlinear optics (NLO). The main goal was preparation of crystalline salts and adducts (cocrystals) of selected nitrogen-containing heterocycles with a range of organic and inorganic acids. Based on previous study and quantum- chemical calculations, the following starting heterocycles were selected: 2-aminopyrimidine, 4-aminopyrimidine, 5-aminopyrimidine, 3-amino-1,2,4-triazine and 3-amino-5,6-dimethyl- 1,2,4-triazine. The prepared materials were characterised mainly by X-ray diffraction and vibrational spectroscopy and the interpretation of the vibrational spectra was based on quantum-chemical calculations. The systems based on aminopyrimidines were the first field of study in presented thesis. The thesis represents a finalisation of our previous study focused on inorganic salts and cocrystal in the case of 2-aminopyrimidine. The characterisation of a pair of cocrystals with boric acid was accomplished. The 12 new salts and adducts were prepared and characterised in the case of 4-aminopyrimidine and only one crystalline product - adduct with succinic acid - was obtained in the case of 5-aminopyrimidine. The systems based on 3-amino-1,2,4-triazine and its...
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Novel technique for characterization of ultrashort optical pulses
Peterka, Pavel ; Kozák, Martin (advisor) ; Ostatnický, Tomáš (referee)
Ultrashort laser pulses are nowadays widely used in both the basic and applied reseach as well as in a wide range of applications. Application of laser pulses requires their complete characterization from the point of view of temporal evolution of field amplitude and frequency on femtosecond timescales. This thesis is focused on a new method for ultrashort pulse characterization, which involves measuring spectral interference between input pulse and the pulse transmitted through a medium with cubic nonlinear susceptibility. The new method is inte- resting compared to the established techniques mainly because of its simplicity, as it requires only one medium with cubic nonlinear susceptibility and a spectro- meter. We have implemented the technique experimentally and determined pulse duration and phase for ideally compressed pulse.
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Synthesis and study of crystalline materials for NLO
Janatková, Tereza ; Němec, Ivan (advisor) ; Vojtíšek, Pavel (referee)
This thesis is focused on preparation and study of new compounds of chosen organic bases with potential use in nonlinear optics. 2-amino-5-nitropyrimidine, 2-amino-4-methylpyrimidine and their salts with inorganic and organic acids are compounds of the main interest. Diffraction and vibrational-spectroscopic methods of characterization were used in combination with quantum chemical calculation methods. Another aim of this thesis was preparation of new salts of chosen pyrimidine derivates with the use of methylsulphonic acid. Part of this section is devoted to completion of pyridinium methylsulphonate phase transition and nonlinear optical property studies.
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High-average power picosecond mid-IR source
Vyvlečka, Michal ; Novák, Ondřej (advisor) ; Trojánek, František (referee)
1 Title: High-average power picosecond mid-IR source Author: Michal Vyvlečka Department: Department of Chemical Physics and Optics Supervisor: Ing. Ondřej Novák, Ph.D., Hilase centre, Institute of Physics of CAS Abstract: High average power wavelength tunable picosecond mid-IR source based on optical parametric generation (OPG) and optical parametric amplification (OPA) is being developed. The conversion system is pumped by an Yb:YAG thin-disk laser delivering 100 W of average power at 100 kHz repetition rate, 1030 nm wavelength, and 2-3 ps pulse width. Part of this fundamental beam pumps an OPG process in a PPLN crystal. The generated wavelength is determined by PPLN's poling period and temperature. Tunability of the signal wavelength between 1.46 µm and 1.95 µm was achieved, the signal beam of 20 mW was generated at 2 W of pump power, when double pass of the beams through PPLN crystal was used. The corresponding idler wavelengths were in range 2.18-3.50 μm. The signal beam was further amplified by OPA process in two KTP crystals, which was pumped by the fundamental beam. The signal beam was amplified up to 2 W at pumping of 38 W. Tuning of the output wavelength was realized by change of the phase-matching angle in KTP crystals. Tunability between 1.70-1.95 µm for signal and 2.18-2.62 µm for idler was...
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Salts of heteroaromatic compounds for NLO
Basová, Miriam ; Němec, Ivan (advisor) ; Kubíček, Vojtěch (referee)
The main target of this bachelor's thesis is the preparation and characterization of novel compounds with expected non-linear optical properties. Starting material for the preparation of new salts was 2,4-diamino-1,3,5-triazine. These salts or co-crystals were prepared by the crystallization with selected inorganic and organic acids. The methods of infrared and Raman spectroscopy along with X-ray diffraction methods were used to characterize the prepared materials. Moreover, the NLO potential of selected molecules was proven by quantum − chemical calculations. These calculations were also used for the interpretation of the vibrational spectra. Finally, the structures with non-centrosymmetric assembly were examined for the second harmonic generation efficiency in powdered samples. Keywords: non-linear optics, 2,4-diamino-1,3,5-triazine, vibrational spectroscopy, structural analysis
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Sum-frequency generation in far-UV spectral region
Martínek, Miroslav ; Kozák, Martin (advisor) ; Ondič, Lukáš (referee)
Nonlinear optics is the area of high field optics, where the dependence of polarization of matter on the electric field of optical radiation cannot be considered as linear. This has important implications for practise, since the superposition principle is no longer valid in nonlinear optics. Thus it is possible to influence light, propagating through material, by another intensive radiation. Nonlinear optical phenomena are important especially for laser technology because they allow to generate light at different wavelengths using various interactions. This thesis is focused on the study of the sum-frequency generation in the far ultraviolet (UV) region of the spectrum. As the radiation source the femtosecond laser system was used. The aim of the study was to theoretically describe generation by nonlinear wave equation and to calculate the dependence of phase-matching angle on generated wavelength. Theoretical results were then verified experimentally in the laboratory. Also the energy of generated pulses and sum-frequency generation efficiency were measured for pulses in spectral region 215-250 nm. The generated pulses will further serve to excite electron-hole pairs in the diamond.
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Studium optických nelinearit v polovodičích a polovodičových nanostrukturách
Kozák, Martin ; Trojánek, František (advisor) ; Herynková, Kateřina (referee) ; Kužel, Petr (referee)
This Ph.D. thesis is focused on the study of optical nonlinearities and dynamics of excited charge carriers in monocrystalline diamond, nanocrystalline diamond and silicon. The dynamics of high density carriers in bulk diamond is investigated in detail (the transition from excitons and free carriers to electron-hole liquid or plasma). We study the picosecond dynamics of electron-hole liquid condensation using several techniques of time-resolved optical spectroscopy and demonstrate its evaporation by femtosecond laser pulses. We also propose two new optical techniques for measurement of lifetime, diffusion coefficient and surface recombination velocity of excitons in diamond. The results obtained by these techniques are described theoretically using diffusion equation and compared with the results obtained by the transient grating diffraction measurement. Further we study two- and three- photon absorption and nonlinear refractive index in diamond. In nanocrystalline diamond we study the second and third harmonic generation and its physical origin. In superlattices of silicon nanocrystals in SiO2 matrix we investigate the nonlinear transient absorption dynamics and carrier diffusion.
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Krystalové inženýrství nových materialů pro nelineární optiku
Fridrichová, Michaela ; Němec, Ivan (advisor) ; Černošek, Zdeněk (referee) ; Schwendt, Peter (referee)
This thesis focuses on preparation of novel compounds suitable for nonlinear optics (NLO). In particular, the target property is the second harmonic generation (SHG) and the group of interest are salts of the cations with delocalized electrons which can serve as carriers of the NLO properties. In particular, four derivatives of the highly interesting molecule of guanidine were selected and their NLO potential was proven by quantum chemical computations. In total, twenty new structures were described and those with the noncentrosymmetric structure assembly were examined for the SHG efficiency. Four of the prepared compounds exhibited a noticeable SHG efficiency, two of them even comparable to urea. The most promising compound, the guanylurea hydrogen phosphite (GUHP), was examined in more detail while many interesting NLO properties were revealed. The results of this work are presented also in 10 attached publications which are an integral part of the thesis. Keywords: nonlinear optics, second harmonic generation, guanidine derivatives, guanylurea, N-phenylbiguanide, N,N-dimethylbiguanide, N,N,N˝-triphenylguanidine
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