@article{AlbersWittrock2011,
  author    = {Albers, Klaus and Wittrock, Ulrich},
  title     = {Optical pump concepts for highly efficient quasi-three-level lasers},
  series = {Appl. Phys. B},
  volume    = {105},
  journal   = {Appl. Phys. B},
  publisher = {Springer},
  doi       = {10.25974/fhms-646},
  url       = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-6467},
  pages     = {245 -- 254},
  year      = {2011},
  abstract  = {Efficient quasi-three-level laser operation requires the generation of the highest possible pump rate from a given pump source. We derive the fundamental scaling laws for the pump rate and we extract optimization criteria for pump concepts from these laws. The analysis is then applied to the thin-disk laser. Based on the results, a novel pump concept for thin-disk lasers is proposed, which allows for several tens of pump beam passes and reduces the optical complexity of conventional pump concepts. Furthermore, the beam quality of the pump source is preserved almost completely, facilitating the highest possible pump rate.},
  language  = {en}
}
@article{VerpoortWittrock2010,
  author    = {Verpoort, Sven and Wittrock, Ulrich},
  title     = {Actuator patterns for unimorph and bimorph deformable mirrors},
  series = {Appl. Opt.},
  volume    = {49},
  journal   = {Appl. Opt.},
  publisher = {OSA},
  doi       = {10.25974/fhms-649},
  url       = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-6490},
  pages     = {G37 -- G46},
  year      = {2010},
  abstract  = {The actuator pattern of an adaptive mirror determines the amplitudes and the fidelities of the mirror deformations that can be achieved. In this study, we analyze and compare different electrode patterns of piezoelectric unimorph deformable mirrors using a numerical finite element model. The analysis allows us to determine the optimum actuator pattern, and it is also applicable to bimorph mirrors. The model is verified by comparing its predictions with experimental results of our prototype of a novel unimorph deformable mirror.},
  language  = {de}
}
@article{HeuckNeumayerKuehletal.2006,
  author    = {Heuck, Hans-Martin and Neumayer, Paul and K{\"u}hl, Thomas and Wittrock, Ulrich},
  title     = {Chromatic aberration in petawatt-class lasers},
  series = {Appl. Phys. B},
  volume    = {84},
  journal   = {Appl. Phys. B},
  publisher = {Springer},
  doi       = {10.25974/fhms-652},
  url       = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-6523},
  pages     = {421 -- 428},
  year      = {2006},
  abstract  = {In order to avoid optical damage and non-linear effects, high-power, high-energy lasers of the petawatt class like PHELIX (petawatt high-energy laser for heavy-ion experiments) use large-aperture optics. Usually, chromatic aberration associated with these optical elements is neglected. By means of numerical simulations, we show how the chromatic aberration affects the focal intensity pattern. In particular, we make quantitative predictions of how chromatic aberration decreases the focused peak intensity. Furthermore, we prove the feasibility of a new interferometer that measures the temporal pulse front distortions which arise from expansion telescopes. We also propose a scheme that pre-compensates these distortions.},
  language  = {en}
}
@article{BuskeWittrock2006,
  author    = {Buske, Ivo and Wittrock, Ulrich},
  title     = {Diffraction analysis of aberrated laser resonators},
  series = {Appl. Phys. B},
  volume    = {83},
  journal   = {Appl. Phys. B},
  doi       = {10.25974/fhms-825},
  url       = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-8252},
  pages     = {229 -- 233},
  year      = {2006},
  abstract  = {A numerical analysis of laser resonators with aberrations is presented. {T}he analysis shows that aberrations lead to large diffraction losses of laser resonators which are laid out to produce diffraction-limited beam quality. {S}tatic or dynamic compensation of the aberrations is possible and would yield much higher output power.},
  language  = {en}
}