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Selection of femtosecond laser pulses
Bažíková, Sára ; Trojánek, František (advisor) ; Zázvorka, Jakub (referee)
Construction of the laser is one of the most important physical advances of modern times. Its use in practice is extremely common and desirable, therefore, it is necessary to push the boundaries of possibilities of this technique still further. Lasers generating ultrashort pulses are widely used in material research for the study of nonlinear effects and ultrafast processes. These lasers have a high repetition rate, which must be reduced for some applications. In this thesis we used femtosecond titanium -sapphire laser from Spectra Physics, whose repetition rate is 80 MHz. The aim of this thesis is to reduce this frequency by using a pulse selector. The key mechanism that utilizes the pulse selector is an acoustooptic modulator that is based on the principle of Bragg diffraction and it is able to select pulses with a frequency of 1 Hz-4 MHz. The end of thesis is measurement of the properties of this selector and its optimization.
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Optical spectroscopy of magnetically ordered materials
Surýnek, Miloslav ; Němec, Petr (advisor) ; Němec, Hynek (referee)
Spintronics is a dynamically developing branch of electronics which for transfer, processing and storing of information use not only electron charge but also its spin. Materials appropriate for a construction of spintronic devices should sustain the spin order for a sufficiently long time enabling a manipulation of spins. Simultaneously, in these materials the spin of electrons should be possible to transport fast and long enough across the device. In this work, heterostructure of GaAs/AlGaAs fulfilling these requirements is investigated by a pump-probe technique. In particular, long spin lifetimes of electrons in the heterostructure are studied using the resonant spin amplification method and with a use of the pulse picker. The nuclear spin polarization and the effect of an applied electric current on the studied heterostructure are also investigated in this work. Spectral filters are used to improve the existing experimental setup for the pump-probe technique and to measure a magnetooptical spectrum of the investigated heterostructure.
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Selection of femtosecond laser pulses
Bažíková, Sára ; Trojánek, František (advisor) ; Zázvorka, Jakub (referee)
Construction of the laser is one of the most important physical advances of modern times. Its use in practice is extremely common and desirable, therefore, it is necessary to push the boundaries of possibilities of this technique still further. Lasers generating ultrashort pulses are widely used in material research for the study of nonlinear effects and ultrafast processes. These lasers have a high repetition rate, which must be reduced for some applications. In this thesis we used femtosecond titanium -sapphire laser from Spectra Physics, whose repetition rate is 80 MHz. The aim of this thesis is to reduce this frequency by using a pulse selector. The key mechanism that utilizes the pulse selector is an acoustooptic modulator that is based on the principle of Bragg diffraction and it is able to select pulses with a frequency of 1 Hz-4 MHz. The end of thesis is measurement of the properties of this selector and its optimization.
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