|
|
Ultrafast dynamics of charge carriers in 2D materials
Koutenský, Petr ; Kozák, Martin (advisor)
Title: Ultrafast dynamics of charge carriers in 2D materials Author: Bc. 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 this thesis was to study ultrafast dynamics of excitons in monolayers of transient metal dichalcogenides WSe2 and MoS2 using methods of ultrafast laser spectroscopy. We focus on two types of processes in this thesis. We measured ultrafast dynamics of carrier recombination and inter-valley scattering of excitons. We also focused on ultrafast manipulation with excitonic energy levels which allows us to remove the energy degeneracy in different minima of the band structure using coherent optical effects (optical Stark effect and Bloch-Siegert shifts). In the future, the observed phenomena could contribute to developement of new utrafast optical and optoelectronical devices exploting so called valley polarization of electrons in the studied materials. Keywords: Ultrashort laser puses, time-resolved laser spectroscopy, nonlinear op- tics, 2D crystals iii
|
|
|
Ultrafast dynamics of charge carriers in 2D materials
Koutenský, Petr ; Kozák, Martin (advisor) ; Galář, Pavel (referee)
Title: Ultrafast dynamics of charge carriers in 2D materials Author: Bc. 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 this thesis was to study ultrafast dynamics of excitons in monolayers of transient metal dichalcogenides WSe2 and MoS2 using methods of ultrafast laser spectroscopy. We focus on two types of processes in this thesis. We measured ultrafast dynamics of carrier recombination and inter-valley scattering of excitons. We also focused on ultrafast manipulation with excitonic energy levels which allows us to remove the energy degeneracy in different minima of the band structure using coherent optical effects (optical Stark effect and Bloch-Siegert shifts). In the future, the observed phenomena could contribute to developement of new utrafast optical and optoelectronical devices exploting so called valley polarization of electrons in the studied materials. Keywords: Ultrashort laser puses, time-resolved laser spectroscopy, nonlinear op- tics, 2D crystals iii
|
|
|
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...
|
guest ::
