@inproceedings{WittrockWelp2006,
  author    = {Wittrock, Ulrich and Welp, Petra},
  title     = {Adaptive laser resonator control with deformable MOEMS mirrors},
  series = {MEMS/MOEMS Components and Their Applications III, Proc. SPIE},
  volume    = {6113},
  booktitle = {MEMS/MOEMS Components and Their Applications III, Proc. SPIE},
  publisher = {SPIE},
  doi       = {10.25974/fhms-653},
  url       = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-6537},
  pages     = {61130C},
  year      = {2006},
  abstract  = {Adaptive laser resonators with deformable MOEMS mirrors under closed-loop control are discussed and experimental results are presented. The requirements for deformable mirrors and for closed-loop control systems of these mirrors are analyzed. Several deformable mirrors have been characterized and the results are presented. Currently available membrane mirrors deform under laser load and need further development before they can be used for aberration correction of solid state lasers above some tens of Watts. Nevertheless, the results are encouraging and the requirements are within reach of currently available technology. Finally, we demonstrate an Nd.YVO4-laser with a closed-loop adaptive resonator and more than 6 W of output power. The closed-loop system was able to compensate artificially introduced aberrations from a phase plate.},
  language  = {de}
}
@article{WittrockVorholt2015,
  author    = {Wittrock, Ulrich and Vorholt, Christian},
  title     = {Spatial hole burning in Yb:YAG thin-disk lasers},
  series = {Appl. Phys. B},
  volume    = {120},
  journal   = {Appl. Phys. B},
  doi       = {10.25974/fhms-823},
  url       = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-8234},
  pages     = {711 -- 721},
  year      = {2015},
  abstract  = {The spatially varying intensity in a standing wave resonator leads to spatial hole burning in the gain medium of a laser. The spatial hole burning changes the gain of different longitudinal modes and can thus determine the optical spectrum of the laser. We simulate this longitudinal mode competition in standing wave resonators of thin-disk lasers. The resulting optical spectra of the laser are compared to measured optical spectra. We examine two types of resonators: I-resonators and V-resonators with different angles of incidence. In V-resonators, the non-normal incidence of the laser beam on the disk lifts the degeneracy of the polarization. Experiments show that the slight gain advantage for the p-polarization does not lead to polarized emission. For both types of resonators, the measured spectra are in good agreement with the simulated ones. The simulations allow to study the influence of spectral intra-cavity losses on the optical spectrum of a thin-disk laser.},
  language  = {en}
}
@article{Wittrock2010,
  author    = {Wittrock, Ulrich},
  title     = {Laryngeally echolocating bats (Brief Communication Arising)},
  series = {Nature},
  volume    = {466},
  journal   = {Nature},
  doi       = {10.1038/nature09156},
  pages     = {E6},
  year      = {2010},
  language  = {mul}
}
@article{Wittrock2014,
  author    = {Wittrock, Ulrich},
  title     = {Grenzen? Welche Grenzen? Prof. Ulrich Wittrock, Leiter des Labors f{\"u}r Photonik an der Fachhochschule M{\"u}nster, fragt nach den ultimativen Grenzen der Lasertechnik},
  series = {Laser Community - das Lasermagazin von Trumpf},
  volume    = {02:14},
  journal   = {Laser Community - das Lasermagazin von Trumpf},
  year      = {2014},
  language  = {de}
}
@article{Wittrock2014,
  author    = {Wittrock, Ulrich},
  title     = {Limitations? What Limitations? Prof. Ulrich Wittrock, head of the Photonics Laboratory at the M{\"u}nster University of Applied Sciences, seeks out the ultimate boundaries of laser technology},
  series = {Laser Community - the laser magazine from Trumpf},
  volume    = {02:14},
  journal   = {Laser Community - the laser magazine from Trumpf},
  year      = {2014},
  language  = {en}
}
@article{VorholtWittrock2015,
  author    = {Vorholt, Christian and Wittrock, Ulrich},
  title     = {Intra-cavity pumped Yb:YAG thin-disk laser with 1.74\% quantum defect},
  series = {Opt. Lett.},
  volume    = {40},
  journal   = {Opt. Lett.},
  doi       = {10.25974/fhms-828},
  url       = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-8284},
  pages     = {4819 -- 4822},
  year      = {2015},
  abstract  = {We present, to the best of our knowledge, the first intracavity pumped Yb:YAG thin-disk laser. It operates at 1050.7 nm with a quantum defect of just 1.74\% due to pumping at 1032.4 nm. Low absorption of the pump light at the pump wavelength of 1032.4 nm is compensated for by placing the disk inside the resonator of another Yb:YAG thin-disk laser which is diode-pumped at 940 nm. The intra-cavity pumped laser has an output power of 10.3 W and a slope efficiency of 8.3\%},
  language  = {en}
}
@inproceedings{VorholtWittrock2015,
  author    = {Vorholt, Christian and Wittrock, Ulrich},
  title     = {Wavelength control by angle-tuning of the laser radiation in an intra-cavity pumped Yb:YAG thin-disk laser},
  series = {Advanced Solid State Lasers (ASSL), paper AM5A.39},
  booktitle = {Advanced Solid State Lasers (ASSL), paper AM5A.39},
  doi       = {10.25974/fhms-829},
  url       = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-8298},
  year      = {2015},
  abstract  = {In an intra-cavity pumped thin-disk laser the pump radiation forms a standing wave pattern inside the intra-cavity pumped disk.We demonstrate experimentally that the grating period of the standing wave pattern of the pump radiation can control the laser wavelength.},
  language  = {en}
}
@article{VorholtWittrock2017,
  author    = {Vorholt, Christian and Wittrock, Ulrich},
  title     = {Single-frequency oscillation of thin-disk lasers due to phase-matched pumping},
  series = {Opt. Expr.},
  volume    = {25},
  journal   = {Opt. Expr.},
  doi       = {10.25974/fhms-1025},
  url       = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-10258},
  pages     = {21388 -- 21399},
  year      = {2017},
  abstract  = {We present a novel pump concept that should lead to single-frequency operation of thin-disk lasers without the need for etalons or other spectral filters. The single-frequency operation is due to matching the standing wave pattern of partially coherent pump light to the standing wave pattern of the laser light inside the disk. The output power and the optical efficiency of our novel pump concept are compared with conventional pumping. The feasibility of our pump concept was shown in previous experiments.},
  language  = {en}
}
@incollection{VerpoortWittrock2009,
  author    = {Verpoort, Sven and Wittrock, Ulrich},
  title     = {Miniaturized adaptive mirror for solid state laser resonators},
  series = {Proceedings of the 7th International Workshop on Adaptive Optics for Industry and Medicine, Shatura, Russia},
  booktitle = {Proceedings of the 7th International Workshop on Adaptive Optics for Industry and Medicine, Shatura, Russia},
  year      = {2009},
  language  = {en}
}
@inproceedings{VerpoortWittrock2011,
  author    = {Verpoort, Sven and Wittrock, Ulrich},
  title     = {Deformable mirrors for high power lasers},
  series = {Proceedings of the 8th International Workshop on Adaptive Optics for Industry and Medicine (AOIM)},
  booktitle = {Proceedings of the 8th International Workshop on Adaptive Optics for Industry and Medicine (AOIM)},
  url       = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-106953},
  year      = {2011},
  abstract  = {It has been shown that the beam quality and the efficiency of high-power solid-state lasers could be enhanced by the use of deformable mirrors in order to compensate for optical aberrations. An intracavity compensation requires a deformable mirror which is capable of handling very high laser intensities. The active diameter of the deformable mirror should be a few millimeters in order to match typical fundamental mode laser beam diameters. There is a wide variety of commercially available deformable mirrors, but neither meets all requirements.},
  language  = {en}
}