Simon Lotz

Doktorand / PhD Student


Universität zu Lübeck
Institut für Biomedizinische Optik

Maria-Goeppert-Str. 1
23562 Lübeck
Gebäude MFC 1, Raum 2.19

Email:
Phone:
+49 451 3101 3229
Fax:
+49 451 3101 3233



Publications

2022

  • M. Klufts, S. Lotz, M. Bashir, S. Karpf and R. Huber: Ultra-high-accuracy chromatic dispersion measurement in optical fibers. in Optical Components and Materials XIX, no. 11997, pp. 146 - 152, SPIE, 2022
    BibTeX Link
    @inproceedings{Klufts2022,
    author = {M. Klufts, S. Lotz, M. Bashir, S. Karpf and R. Huber},
    title = {{Ultra-high-accuracy chromatic dispersion measurement in optical fibers}},
    volume = {11997},
    booktitle = {Optical Components and Materials XIX},
    editor = {Shibin Jiang and Michel J. F. Digonnet},
    organization = {International Society for Optics and Photonics},
    publisher = {SPIE},
    pages = {146 -- 152},
    keywords = {AG-Huber_FDML, Dispersion measurement, Chromatic dispersion, fiber dispersion measurement, optical component characterization, tunable laser, FDML},
    year = {2022},
    
    url = {https://zenodo.org/record/6406367#.YkcF3TWxX8A},
    }
    
  • M. Göb, S. Burhan, S. Lotz and R. Huber: Towards ultra-large area vascular contrast skin imaging using multi-MHz-OCT. in Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XXVI, no. 11948, pp. 27 - 31, SPIE, 2022
    BibTeX Link
    @inproceedings{Goeb2022BiOS,
    author = {M. Göb, S. Burhan, S. Lotz and R. Huber},
    title = {{Towards ultra-large area vascular contrast skin imaging using multi-MHz-OCT}},
    volume = {11948},
    booktitle = {Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XXVI},
    editor = {Joseph A. Izatt and James G. Fujimoto},
    organization = {International Society for Optics and Photonics},
    publisher = {SPIE},
    pages = {27 -- 31},
    keywords = {AG-Huber_FDML, AG-Huber_OCT, Optical Coherence Tomography, Fourier Domain Mode Locking, FDML, Optical Coherence Angiography, OCTA, Medical optics and biotechnology, Medical imaging, Three-dimensional image acquisition, Scanners, Microscopy},
    year = {2022},
    doi = {10.1117/12.2612171},
    }
  • M. Göb, T. Pfeiffer, W. Draxinger, S. Lotz, J.P. Kolb and R. Huber: Continuous spectral zooming for in vivo live 4D-OCT with MHz A-scan rates and long coherence. Biomed. Opt. Express, no. 13, pp. 713-727, OSA, Feb, 2022
    BibTeX Link
    @article{Goeb2022,
    author = {M. G\"{o}b, T. Pfeiffer,  W. Draxinger, S. Lotz, J.P. Kolb and R. Huber},
    journal = {Biomed. Opt. Express},
    keywords = {AG-Huber_OCT;AG-Huber_FDML; High speed imaging; Image processing; Image quality; In vivo imaging; Range imaging; Vertical cavity surface emitting lasers},
    number = {2},
    pages = {713--727},
    publisher = {OSA},
    title = {Continuous spectral zooming for in vivo live 4D-OCT with MHz A-scan rates and long coherence},
    volume = {13},
    month = {Feb},
    year = {2022},
    doi = {10.1364/BOE.448353},
    abstract = {We present continuous three-dimensional spectral zooming in live 4D-OCT using a home-built FDML based OCT system with 3.28 MHz A-scan rate. Improved coherence characteristics of the FDML laser allow for imaging ranges up to 10 cm. For the axial spectral zoom feature, we switch between high resolution and long imaging range by adjusting the sweep range of our laser. We present a new imaging setup allowing for synchronized adjustments of the imaging range and lateral field of view during live OCT imaging. For this, a novel inline recalibration algorithm was implemented that enables numerical k-linearization of the raw OCT fringes for every frame instead of every volume. This is realized by acquiring recalibration data within the dead time of the raster scan at the turning points of the fast axis scanner. We demonstrate in vivo OCT images of fingers and hands at different resolution modes and show real three-dimensional zooming during live 4D-OCT. A three-dimensional spectral zooming feature for live 4D-OCT is expected to be a useful tool for a wide range of biomedical, scientific and research applications, especially in OCT guided surgery.},
    }
    
    

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},
    
    }