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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.
