Katharina Rewerts

Doktorandin / PhD Student


Universität zu Lübeck
Institut für Biomedizinische Optik

Maria-Goeppert-Str. 1
23562 Lübeck
Gebäude MFC 1, Raum 2.24

Email:
Phone:
+49 451 3101 3234
Fax:
+49 451 3101 3233



Publications

2021

  • C. Grill, S. Lotz, T. Blömker, M. Schmidt, W. Draxinger, J.P. Kolb, C. Jirauschek and R. Huber: Superposition of two independent FDML lasers. in 2021 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference (CLEO/Europe-EQEC), pp. 1-1, 2021
    BibTeX Link
    @inproceedings{grill2021superposition,
      title={Superposition of two independent FDML lasers},
      author={C. Grill, S. Lotz, T. Bl{\"o}mker, M. Schmidt, W. Draxinger, J.P. Kolb, C. Jirauschek and R. Huber},
      booktitle={2021 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference (CLEO/Europe-EQEC)},
      pages={1--1},
      year={2021},
      organization={IEEE},
    keywords={  AG-Huber_FDML},
    url = {"https://ieeexplore.ieee.org/abstract/document/9542126"}
    }
  • M. Schmidt, C. Grill, S. Lotz, T. Pfeiffer, R. Hubert and C. Jirauschek: Intensity pattern types in broadband Fourier domain mode-locked (FDML) lasers operating beyond the ultra-stable regime. Applied Physics B, no. 127, pp. 60, 2021
    BibTeX Link
    @Article{Schmidt2021,
      author   = {M. Schmidt, C. Grill, S. Lotz, T. Pfeiffer, R. Hubert and C. Jirauschek},
      journal  = {Applied Physics B},
      title    = {Intensity pattern types in broadband Fourier domain mode-locked (FDML) lasers operating beyond the ultra-stable regime},
      year     = {2021},
      issn     = {1432-0649},
      number   = {5},
      pages    = {60},
      volume   = {127},
    keywords={AG-Huber_FDML},
      abstract = {We report on the formation of various intensity pattern types in detuned Fourier domain mode-locked (FDML) lasers and identify the corresponding operating conditions. Such patterns are a result of the complex laser dynamics and serve as an ideal tool for the study of the underlying physical processes as well as for model verification. By numerical simulation we deduce that the formation of patterns is related to the spectral position of the instantaneous laser lineshape with respect to the transmission window of the swept bandpass filter. The spectral properties of the lineshape are determined by a long-term accumulation of phase-offsets, resulting in rapid high-amplitude intensity fluctuations in the time domain due to the narrow intra-cavity bandpass filter and the fast response time of the semiconductor optical amplifier gain medium. Furthermore, we present the distribution of the duration of dips in the intensity trace by running the laser in the regime in which dominantly dips form, and give insight into their evolution over a large number of roundtrips.},
      doi      = {10.1007/s00340-021-07600-1},
      refid    = {Schmidt2021},
    }
  • T. Pfeiffer, T. Klein, A. Mlynek, W. Wieser, S. Lotz, C. Grill and R. Huber: High finesse tunable Fabry-Perot filters in Fourier-domain modelocked lasers. in Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XXV, no. 11630, SPIE, 2021
    BibTeX Link
    @inproceedings{Pfeiffer2021,
    author = {T. Pfeiffer, T. Klein, A. Mlynek, W. Wieser, S. Lotz, C. Grill and R. Huber},
    title = {{High finesse tunable Fabry-Perot filters in Fourier-domain modelocked lasers}},
    volume = {11630},
    booktitle = {Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XXV},
    editor = {Joseph A. Izatt and James G. Fujimoto},
    organization = {International Society for Optics and Photonics},
    publisher = {SPIE},
    abstract = {We demonstrate that the coherence roll-off and dynamic range of OCT systems using Fourier-domain mode-locked (FDML) lasers can be significantly improved by a fiber Fabry-Perot tunable filter (FFP-TF) with a finesse of more than 3000, a more than fivefold improvement over previous designs. In contrast to previous work, standard resampling using a pre-acquired signal (as in SD-OCT) with no k-clocking is sufficient for 20 nm and 100 nm sweep range, significantly reducing the system complexity. 3D-OCT imaging at 20 cm imaging range is demonstrated.},
    keywords = {AG-Huber_FDML, AG-Huber_OCT, optical coherence tomography, FDML laser, swept source laser, high finesse, Fabry-Perot, MHz-OCT, OCT, tunable laser},
    year = {2021},
    URL = {hhttps://doi.org/10.1117/12.2583501}
    }
  • S. Lotz, C. Grill, M. Göb, W. Draxinger, J. P. Kolb and R. Huber: Characterization of the dynamics of an FDML laser during closed-loop cavity length control. in Fiber Lasers XVIII: Technology and Systems, no. 11665, pp. 236 - 241, SPIE, 2021
    BibTeX Link
    @inproceedings{LotzLASE2021,
    author = {S. Lotz, C. Grill, M. Göb, W. Draxinger, J. P. Kolb and R. Huber},
    title = {{Characterization of the dynamics of an FDML laser during closed-loop cavity length control}},
    volume = {11665},
    booktitle = {Fiber Lasers XVIII: Technology and Systems},
    editor = {Michalis N. Zervas},
    organization = {International Society for Optics and Photonics},
    publisher = {SPIE},
    pages = {236 -- 241},
    abstract = {In Fourier domain mode locked (FDML) lasers, extremely precise and stable matching of the filter tuning period and light circulation time in the cavity is essential for ultra-low noise operation. During the operation of FDML lasers, the ultra-low noise mode can be lost due to temperature drifts of the already temperature stabilized cavity resulting in increased intensity noise. Until now, the filter frequency is continuously regulated to match the changing light circulation time. However, this causes the filter frequency to constantly change by a few mHz and leads to synchronization issues in cases where a fixed filter frequency is desired. We present an actively cavity length controlled FDML laser and a robust and high precision feedback loop algorithm for maintaining ultra-low noise operation. Instead of adapting the filter frequency, the cavity length is adjusted by a motorized free space beam path to match the fixed filter frequency. The closed-loop system achieves a stability of ~0.18 mHz at a sweep repetition rate of ~418 kHz which corresponds to a ratio of 4×10<sup>-10</sup>. We investigate the coherence properties during the active cavity length adjustments and observe no noise increase compared to fixed cavity length. The cavity length control is fully functional and for the first time, offers the possibility to operate an FDML laser in sweet spot mode at a fixed frequency or phase locked to an external clock. This opens new possibilities for system integration of FDML lasers.},
    keywords = {AG-Huber_FDML, FDML, Fourier domain mode locking, laser beating, tunable laser, optical coherence tomography, OCT},
    year = {2021},
    URL = {hhttps://doi.org/10.1117/12.2578514}
    }
  • S. Lotz, C. Grill, M. Göb, W. Draxinger, J.P. Kolb and R. Huber: Cavity length control for Fourier domain mode locked (FDML) lasers with µm precision. Biomedical Optics Express, no. 12(5), pp. 2604-2616, 2021
    BibTeX Link
    @article{Lotz2021,
       author = {S. Lotz, C. Grill, M. Göb, W. Draxinger, J.P. Kolb and R. Huber},
       title = {Cavity length control for Fourier domain mode locked (FDML) lasers with µm precision},
       journal = {Biomedical Optics Express},
       volume = {12(5)},
       keywords={AG-Huber_FDML},
       pages = {2604-2616},
       url = {https://doi.org/10.1364/BOE.422898},
       year = {2021},
       type = {Journal Article}
    }
    

2020

  • C. Grill, S. Lotz, T. Blömker, D. Kastner, T. Pfeiffer, S. Karpf, M. Schmidt, W. Draxinger C. Jirauschek and R. Huber: Beating of two FDML lasers in real time. in Fiber Lasers XVII: Technology and Systems, no. 11260, pp. 132 - 138, SPIE, 2020
    BibTeX Link Datei
    @inproceedings{Grill2020,
    author = {C. {Grill}, S. {Lotz}, T. {Blömker}, D. {Kastner}, T. {Pfeiffer}, S. {Karpf}, M. {Schmidt}, W. {Draxinger}, C. 
     {Jirauschek} and R. {Huber}},
    title = {{Beating of two FDML lasers in real time}},
    volume = {11260},
    booktitle = {Fiber Lasers XVII: Technology and Systems},
    editor = {Liang Dong},
    organization = {International Society for Optics and Photonics},
    publisher = {SPIE},
    pages = {132 -- 138},
    keywords = {AG-Huber_FDML, FDML laser, fiber lasers, beat signal, OCT, Optical Coherence Tomography, Fourier domain mode locking},
    year = {2020},
    doi = {10.1117/12.2545794},
    
    }