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Fakultät für Physik - Digitale Hochschulschriften der LMU - Teil 05/05 Podcast
A laser source for the generation of intense attosecond pulses and its first applications

A laser source for the generation of intense attosecond pulses and its first applications

Fakultät für Physik - Digitale Hochschulschriften der LMU - Teil 05/05 vor 11 Jahren

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The continuous development and improvement of laser sources has
steadily increased the number of applications and pushed the limit
of high precision measurements in various fields. The goal of the
work presented in this thesis is to improve the spectrally
broadened Ti:sapphire laser system used for isolated extreme
ultraviolet (XUV) pulse generation, which has, in the last decade,
allowed the study of electron dynamics on a sub-femtosecond (1 fs =
10^-15 s) level and delivered new insights into ultrafast dynamics
of electrons in atoms, molecules and solids. By adding a second
stage amplifier to the commonly used one-stage chirped pulse
amplification laser system the compressed output power of a sub-5
fs laser system has been tripled to 1.5 mJ. A crucial part for
achieving this result is the comparison of two different efficient
compressor setups in order to optimize the compression. With these
higher pulse energies, it is possible to increase the generated
photon ux in an isolated attosecond (10^-18 s) pulse and to push
the XUV photon energy higher. Run at 4 kHz repetition rate,
integrative measurements with sub-2 cycle laser pulses can be
conducted much faster than with most laser sources in this energy
range. The resulting pulses are used for high-harmonic generation
(HHG) and characterized via attosecond streaking, demonstrating
excellent stability and quality of the whole laser system. First
experiments with these pulses were conducted by probing the
temporal behavior of the photo-emission of the giant resonance of
4d electrons in xenon with broadband XUV-pulses at 100 eV and
inducing and measuring the nonlinear propagation in fused silica at
high intensities via its effect on the waveform of the ultra-short
visible-near-infrared pulse measured by means of attosecond
streaking. The higher pulse energy of the driving laser field will
also prove to be very useful as soon as nonlinear effects besides
HHG contribute to the pump and probe setup e.g. an ultrashort
UV-pulse is used to pump electron dynamics which are subsequently
probed with high temporal resolution by the XUV-pulse.