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@PHDTHESIS{Deppe:417787,
      author       = {Deppe, Bastian},
      othercontributors = {Kraenkel, Christian and Küpper, Jochen},
      title        = {{H}igh-intracavity-power thin-disk laser for the alignment
                      of molecules},
      school       = {University of Hamburg},
      type         = {Dissertation},
      reportid     = {PUBDB-2018-05902},
      pages        = {137},
      year         = {2019},
      note         = {Dissertation, University of Hamburg, 2018},
      abstract     = {The subject of this thesis was the development of a
                      thin-disk laser with a continuous waveintracavity intensity
                      of more than $10^{10} {W}{cm^{-2}}$ for the adiabatic
                      alignment ofmolecules. In particular, this necessitates an
                      intracavity power of more than 100 kW, aninternal focus with
                      a radius of 20 µm, a well-defined and stable polarization,
                      and benefitsfrom fundamental transverse mode operation. For
                      this purpose, ytterbium-doped host materials werecompared in
                      various resonators, exploring their losses and their
                      suitability for such a lasersystem. The study focused on the
                      possible implementation of such a laser setup, notably for
                      pumppowers below 500 W, which allow resonator losses of
                      approx. $5 \times 10^{-3}$. A characterizationof YAG and LuO
                      in an efficient and short linear multi-transverse-mode
                      resonator revealed resonatorinternal losses in the order of
                      $2 \times 10^{-4}$. No dependency on the gain material could
                      be resolved.Measurements of the losses with more than 20
                      thin disks pointed towards losses originating at
                      theirsurface. An intracavity power of 130 kW could be
                      demonstrated. This corresponds to anenhancement by a factor
                      of 2500 with respect to the incident pump power of 54 W.
                      Furtherscaling of the pump intensity was restrained by
                      optical damage, mostly in the form of nodular pointdefects,
                      which were observed at optics and disks. The optical damage
                      is believed to be caused bydefects in the highly reflective
                      coatings. The resonator internal losses for
                      linearsingle-transverse-mode resonators increased up to $9
                      \times 10^{-4}$, which might have been caused byadditional
                      diffraction losses. The application of a Brewster window to
                      ensure a stable polarizationadditionally led to an increase
                      of losses to $1.5 \times 10^{-3}$. Supposedly, it was caused
                      bystress-induced birefringence in the isotropic gain
                      materials. This induced a rotation of thepolarization and
                      eventually contributed to significant reflection losses at
                      the Brewster plate.Additionally, an intrinsic polarization
                      was measured, which was less stable than the beforementioned
                      polarization but avoided additional losses. Similar
                      behaviors were detected for foldedresonators. Those were
                      more suitable for acquiring a tight internal focus. Imaging
                      the Rayleighscattering at atmospheric molecules allowed an
                      in vitro determination of the caustic. Here,
                      anintracavity-focus-radius in the order of 20 µm was
                      measured. However, resonator losses ofapprox. 5 \% and the
                      prevalent optical damage obstructed the achievement of the
                      requiredintracavity powers with the available pump powers.
                      Comparisons and calculations of possible lossessuggested the
                      diffraction losses, caused by astigmatic distortions of the
                      disks, being responsible.To accomplish the goals, a
                      combination of a decrease of losses and an increase of the
                      pump powermight be necessary.},
      cin          = {FS-CFEL-1 / FS-CFEL-CMI / UNI/CUI / UNI/EXP},
      cid          = {I:(DE-H253)FS-CFEL-1-20120731 /
                      I:(DE-H253)FS-CFEL-CMI-20220405 /
                      $I:(DE-H253)UNI_CUI-20121230$ /
                      $I:(DE-H253)UNI_EXP-20120731$},
      pnm          = {6211 - Extreme States of Matter: From Cold Ions to Hot
                      Plasmas (POF3-621) / CUI - Hamburger Zentrum für
                      ultraschnelle Beobachtung (194651731)},
      pid          = {G:(DE-HGF)POF3-6211 / G:(GEPRIS)194651731},
      experiment   = {EXP:(DE-MLZ)NOSPEC-20140101},
      typ          = {PUB:(DE-HGF)11},
      doi          = {10.3204/PUBDB-2018-05902},
      url          = {https://bib-pubdb1.desy.de/record/417787},
}