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Abstract

The main subject of this master thesis was the construction of a pulse shaper which is able to modulate femtosecond pulses of less than 20 fs duration using a programmable liquid crystal modulator. This is done primarily by changing the spectral phase of the light pulse. The modulator can create a desired spectral phase function, which causes a change of the pulse spectrum, whose Fourier transform results in the temporally shaped intensity profile of the femtosecond pulse. Part of this work was also the development of a simulation based on Mathematica which is able to calculate by entering a certain phase function the modulated waveform of the ultrashort pulse. For the characterization of the pulse shaper, the M² of a He-Ne laser beam before and after passing the pulse shaper was measured. In addition, the auto-correlation signal of the femtosecond laser after the pulse shaper with and without phase function could be determined . The comparison of both signals resulted in a change in the auto-correlation signal when the liquid crystal modulator was enabled, which is due to the change of the temporal intensity profile of the light pulse.