@article{https://doi.org/10.1002/smll.202401472,
author = {Karpf, Sebastian and Glöckner Burmeister, Nina and Dubreil, Laurence and Ghosh, Shayantani and Hollandi, Reka and Pichon, Julien and Leroux, Isabelle and Henkel, Alessandra and Lutz, Valerie and Jurkevičius, Jonas and Latshaw, Alexandra and Kilin, Vasyl and Kutscher, Tonio and Wiggert, Moritz and Saavedra-Villanueva, Oscar and Vogel, Alfred and Huber, Robert A. and Horvath, Peter and Rouger, Karl and Bonacina, Luigi},
title = {Harmonic Imaging of Stem Cells in Whole Blood at GHz Pixel Rate},
journal = {Small},
volume = {n/a},
number = {n/a},
pages = {2401472},
keywords = {fiber lasers, harmonic imaging, multiphoton microscopy, nanoparticles, regenerative medicine, SHG, SLIDE},
doi = {https://doi.org/10.1002/smll.202401472},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/smll.202401472},
eprint = {https://onlinelibrary.wiley.com/doi/pdf/10.1002/smll.202401472},
abstract = {Abstract The pre-clinical validation of cell therapies requires monitoring the biodistribution of transplanted cells in tissues of host organisms. Real-time detection of these cells in the circulatory system and identification of their aggregation state is a crucial piece of information, but necessitates deep penetration and fast imaging with high selectivity, subcellular resolution, and high throughput. In this study, multiphoton-based in-flow detection of human stem cells in whole, unfiltered blood is demonstrated in a microfluidic channel. The approach relies on a multiphoton microscope with diffractive scanning in the direction perpendicular to the flow via a rapidly wavelength-swept laser. Stem cells are labeled with metal oxide harmonic nanoparticles. Thanks to their strong and quasi-instantaneous second harmonic generation (SHG), an imaging rate in excess of 10 000 frames per second is achieved with pixel dwell times of 1 ns, a duration shorter than typical fluorescence lifetimes yet compatible with SHG. Through automated cell identification and segmentation, morphological features of each individual detected event are extracted and cell aggregates are distinguished from isolated cells. This combination of high-speed multiphoton microscopy and high-sensitivity SHG nanoparticle labeling in turbid media promises the detection of rare cells in the bloodstream for assessing novel cell-based therapies.}
}

@INPROCEEDINGS{10232141,
  author={Lamminger, Philipp and Hakert, Hubertus and Lotz, Simon and Kolb, Jan Philip and Kutscher, Tonio and Karpf, Sebastian and Huber, Robert},
  booktitle={2023 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)}, 
  title={Four-Wave Mixing Fast Wavelength Sweeping FDML Laser with kW Peak Power at 900 nm and 1300 nm}, 
  year={2023},
  volume={},
  number={},
  pages={1-1},
  doi={10.1109/CLEO/Europe-EQEC57999.2023.10232141}}

@article{Lamminger:23,
author = {Philipp Lamminger and Hubertus Hakert and Simon Lotz and Jan Philip Kolb and Tonio Kutscher and Sebastian Karpf and Robert Huber},
journal = {Opt. Lett.},
keywords = {Green fluorescent protein; Laser beam combining; Laser crystals; Laser imaging; Optical amplifiers; Photonic crystal lasers},
number = {14},
pages = {3713--3716},
publisher = {Optica Publishing Group},
title = {Four-wave mixing seeded by a rapid wavelength-sweeping FDML laser for nonlinear imaging at 900 nm and 1300 nm},
volume = {48},
month = {Jul},
year = {2023},
url = {https://opg.optica.org/ol/abstract.cfm?URI=ol-48-14-3713},
doi = {10.1364/OL.488181},
abstract = {Four-wave mixing (FWM) enables the generation and amplification of light in spectral regions where suitable fiber gain media are unavailable. The 1300 nm and 900 nm regions are of especially high interest for time-encoded (TICO) stimulated Raman scattering microscopy and spectro-temporal laser imaging by diffracted excitation (SLIDE) two-photon microscopy. We present a new, to the best of our knowledge, FWM setup where we shift the power of a home-built fully fiber-based master oscillator power amplifier (MOPA) at 1064 nm to the 1300-nm region of a rapidly wavelength-sweeping Fourier domain mode-locked (FDML) laser in a photonic crystal fiber (PCF) creating pulses in the 900-nm region. The resulting 900-nm light can be wavelength swept over 54 nm and has up to 2.5 kW (0.2 {\textmu}J) peak power and a narrow instantaneous spectral linewidth of 70 pm. The arbitrary pulse patterns of the MOPA and the fast wavelength tuning of the FDML laser (419 kHz) allow it to rapidly tune the FWM light enabling new and faster TICO-Raman microscopy, SLIDE imaging, and other applications.},
}

@inproceedings{10.1117/12.2649663,
author = {Philipp Lamminger and Hubertus Hakert and Simon Lotz and Jan Philip Kolb and Tonio Kutscher and Sebastian Karpf and Robert Huber},
title = {{900 nm swept source FDML laser with kW peak power}},
volume = {12400},
booktitle = {Fiber Lasers XX: Technology and Systems},
editor = {V.  R. Supradeepa},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {124001I},
abstract = {A wavelength agile 900 nm 2.5 kW peak power fiber laser is created by four-wave mixing (FWM) in a photonic crystal fiber (PCF), while amplifying a 1300 nm Fourier-domain mode-locked (FDML) laser. The FWM process is pumped by a home-built 1064 nm master oscillator power amplifier (MOPA) laser and seeded by a home-built 1300 nm FDML laser, generating high power pulses at wavelengths, where amplification by active fiber media is difficult. The 900 nm pulses have a spectral linewidth of 70 pm, are tunable over 54 nm and have electronic pulse-to-pulse tuning capability. These pulses can be used for nonlinear imaging like two-photon or coherent anti-Stokes Raman microscopy (CARS) microscopy including spectro-temporal laser imaging by diffracted excitation (SLIDE) and time-encoded (Tico) stimulated Raman microscopy.},
keywords = {Fourier domain mode locking,  FDML, Raman, two photon microscopy, SLIDE, 900 nm, fiber laser, photonic crystal fiber, swept source},
year = {2023},
doi = {10.1117/12.2649663},
URL = {https://doi.org/10.1117/12.2649663}
}

@article{STRAUCH2023e210,
title = {Accelerating intraoperative tumor histology with sectioning-free multiphoton microscopy},
journal = {European Journal of Surgical Oncology},
volume = {49},
number = {2},
pages = {e210},
year = {2023},
issn = {0748-7983},
doi = {https://doi.org/10.1016/j.ejso.2022.11.575},
url = {https://www.sciencedirect.com/science/article/pii/S0748798322013245},
author = {Matthias Strauch and Jan Philip Kolb and Christian Rose and Nadine Merg and Jennifer Hundt and Christiane Kümpers and Sven Perner and Sebastian Karpf and Robert Huber}
}

@article{Meyer:23,
author = {Stefan Meyer and Tonio F. Kutscher and Philipp Lamminger and Florian Sommer and Sebastian Karpf},
journal = {Opt. Continuum},
keywords = {Femtosecond pulses; Fluorescence lifetime imaging; Phase modulation; Picosecond pulses; Single mode lasers; Ultrashort pulses},
number = {11},
pages = {2298--2307},
publisher = {Optica Publishing Group},
title = {Leveraging the periodic interference condition in electro-optic modulators for picosecond pulse generation},
volume = {2},
month = {Nov},
year = {2023},
url = {https://opg.optica.org/optcon/abstract.cfm?URI=optcon-2-11-2298},
doi = {10.1364/OPTCON.500969},
abstract = {Ultra-short optical pulses in the femtosecond and picosecond regime are typically generated using mode-locked lasers. However, in mode-locking, the pulse repetition rate is fundamentally linked to the cavity length of the laser, making it difficult to synchronize these laser pulses to other light sources. Here, we apply a pulse-on-demand approach to picosecond pulse generation with an electro-optic intensity modulator (EOM). The high, 40 GHz bandwidth of the EOM enables low picosecond pulses, however it shifts the problem of pulse generation to the electronic pulses, requiring high bandwidth electronics. In this study, we present an electro-optic operation, leveraging the periodic interference condition of intensity EOMs by operating it with rising edges at twice its V$\pi$ voltage. Utilizing this method, pulse durations as short as 10.9 ps were achieved by employing a 35 ps edge from an arbitrary waveform generator. The pulses were measured directly on a high-speed oscilloscope as well as indirectly through the spectral broadening of the generated optical pulses. We employ this approach to show arbitrary pulse length generation by applying step functions with only one V$\pi$ voltage, thus permitting direct pulse-on-demand generation of pulses with arbitrary pulse length, shape and repetition rate for applications in spectroscopy, sensing and nonlinear imaging.},
}

@article{Kutscher:23,
author = {Tonio F. Kutscher and Philipp Lamminger and Anton Gruber and Christina Leonhardt and Annika Hunold and Robert A. Huber and Sebastian Karpf},
journal = {Opt. Lett.},
keywords = {Erbium-doped fiber amplifiers; Laser imaging; Laser sources; Lidar; Multiphoton microscopy; Picosecond pulses},
number = {23},
pages = {6096--6099},
publisher = {Optica Publishing Group},
title = {Pulsed swept-source FDML-MOPA laser with kilowatt picosecond pulses around 1550 nm},
volume = {48},
month = {Dec},
year = {2023},
url = {https://opg.optica.org/ol/abstract.cfm?URI=ol-48-23-6096},
doi = {10.1364/OL.500943},
abstract = {Swept-source lasers are versatile light sources for spectroscopy, imaging, and microscopy. Swept-source-powered multiphoton microscopy can achieve high-speed, inertia-free point scanning with MHz line-scan rates. The recently introduced spectro-temporal laser imaging by diffractive excitation (SLIDE) technique employs swept-source lasers to achieve kilohertz imaging rates by using a swept-source laser in combination with a diffraction grating for point scanning. Multiphoton microscopy at a longer wavelength, especially in the shortwave infrared (SWIR) region, can have advantages in deep tissue penetration or applications in light detection and ranging (LiDAR). Here we present a swept-source laser around 1550 nm providing high-speed wavelength agility and high peak power pulses for nonlinear excitation. The swept-source laser is a Fourier-domain mode-locked (FDML) laser operating at 326 kHz sweep rate. For high peak powers, the continuous wave (cw) output is pulse modulated to short picosecond pulses and amplified using erbium-doped fiber amplifiers (EDFAs) to peak powers of several kilowatts. This FDML-master oscillator power amplifier (FDML-MOPA) setup uses reliable, low-cost fiber components. As proof-of-principle measurement, we show third-harmonic generation (THG) using harmonic nanoparticles at the 10 MHz pulse excitation rate. This new, to the best of our knowledge, laser source provides unique performance parameters for applications in nonlinear microscopy, spectroscopy, and ranging.},
}

@inproceedings{10.1117/12.2670881,
author = {Dirk Theisen-Kunde and Florian Sommer and Veit Danicke and Lion Sch{\"u}tzeck and Stefan Meyer and Christopher Kren and Maximilian Rixius and Sebastian Karpf},
title = {{Small footprint SLIDE demonstrator for 40Hz volume rate multiphoton microscopy}},
volume = {12630},
booktitle = {Advances in Microscopic Imaging IV},
editor = {Emmanuel Beaurepaire and Adela Ben-Yakar and YongKeun Park},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {126300Q},
keywords = {multiphoton microscopy, flow cytometry, Fourier Domain Mode Locked Laser, SLIDE, kHz- Imaging},
year = {2023},
doi = {10.1117/12.2670881},
URL = {https://doi.org/10.1117/12.2670881}
}

@article{Grill2022,
  doi = {10.1038/s42005-022-00960-w},
  year = {2022},
  publisher = {Springer Science and Business Media {LLC}},
  volume = {{5}},
  number = {{1}},
  author = {C. Grill, T. Bl\"{o}mker, M. Schmidt, D. Kastner, T. Pfeiffer, J.P. Kolb, W. Draxinger, S. Karpf, C. Jirauschek and R. Huber},
  title = {Towards phase-stabilized Fourier domain mode-locked frequency combs},
  journal = {{Communications Physics}},
keywords={AG-Huber_FDML, FDML, Fourier domain mode locking, phase, frequency comb, coherence, beating}
}

@inproceedings{10.1117/12.2608773,
author = {M. Klufts and S. Lotz and M. Bashir and 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 = {119970L},
abstract = {The chromatic dispersion in optical fibers is a key property for applications where a broadband light source is used and the timing of each individual wavelength is crucial. Counteracting the timing offset introduced by the fiber is a challenge in many applications especially in mode locked lasers. The dispersion parameters need to be measured with high precision. The length of the fiber, the temperature, and the used wavelength will highly impact the amount of dispersion and the accuracy of the measurement. We developed an ultra-high-accuracy dispersion measurement setup at 1080 ± 50 nm considering all the parameters that may influence the measurement. It is based on a home-built wavelength tunable laser where the output is modulated by an electro-optical modulator connected to a 24 GSamples/s arbitrary waveform generator to a complex pattern consisting of pulses and a 4 GHz sine wave. After passing through the fiber the signal is measured with an 80 GSamples/s real time oscilloscope. The fiber’s temperature is controlled to allow for reproducible measurements over several days and we achieve timing measurement accuracies down to ~200 fs. We also present the performance of the setup at ~850 nm. We will discuss and quantify all effects which can negatively impact the system accuracy and we will report on more cost-effective options using lower performance equipment.},
keywords = {Dispersion measurement, Chromatic dispersion, fiber dispersion measurement, optical component characterization, tunable laser, FDML},
year = {2022},
doi = {10.1117/12.2608773},
URL = {https://doi.org/10.1117/12.2608773}
}

@article{Hakert2021,
   author = {H. Hakert, M. Eibl, M. Tillich, R.Pries, G. Hüttmann, R. Brinkmann, B. Wollenberg, K-L. Bruchhage, S. Karpf and R. Huber},
   title = {Time-encoded stimulated Raman scattering microscopy of tumorous human pharynx tissue in the fingerprint region from 1500–1800  cm-1},
   journal = {Optics Letters},
   volume = {46(14)},
   number = {14},
   pages = {3456-3459},
keywords = {AG-Huber_NL, Clinical applications, Master oscillator power amplifiers, Optical coherence tomography, Raman scattering, Stimulated Raman scattering, Stimulated scattering},
   DOI = {https://doi.org/10.1364/OL.424726},
   year = {2021},
   type = {Journal Article}
}

@inproceedings{Grill2021,
author = {C. Grill, T. Blömker, M. Schmidt, D. Kastner, T. Pfeiffer, J.P. Kolb, W. Draxinger, S. Karpf, C. Jirauschek and R. Huber},
title = {{A detailed analysis of the coherence and field properties of an FDML laser by time resolved beat signal measurements}},
volume = {11665},
booktitle = {Fiber Lasers XVIII: Technology and Systems},
editor = {Michalis N. Zervas},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {242 -- 247},
keywords = {AG-Huber_FDML, Fourier domain mode locking, FDML laser, laser beating , tunable laser, optical coherence tomography, OCT},
year = {2021},
URL = {hhttps://doi.org/10.1117/12.2578293}
}

@Conference{Lamminger2021,
  author    = {P. Lamminger, M. Loop, J. Klee, D. Weng, J.P. Kolb, M. Strauch, S. Karpf and R. Huber},
  booktitle = {Multimodal Biomedical Imaging XVI},
  title     = {Combination of two-photon microscopy and optical coherence tomography with fully fiber-based lasers for future endoscopic setups},
  year      = {2021},
  publisher = {SPIE},
  doi       = {10.1117/12.2578679},
  keywords  = {AG-Huber_NL, AG-Huber_OCT},
}

@inproceedings{RN5318,
   author = {Strauch, M;Kolb, J P;Draxinger, W;Popp, A-K;Wacker, M;Merg, N;Hundt, J;Karpf, S and Huber, R},
   title = {Sectioning-free virtual H&E histology with fiber-based two-photon microscopy},
   booktitle = {SPIE BiOS},
   publisher = {SPIE},
   volume = {11648},
Year = {2021},
   DOI = {https://doi.org/10.1117/12.2578334},
   url = {https://doi.org/10.1117/12.2578334},
   type = {Conference Proceedings}
}

@Conference{Strauch2021b,
  author    = {M. Strauch, J.P. Kolb, C. Rose, N. Merg, J. Hundt, C. Kümpers, S. Perner, S. Karpf and R. Hubert},
  booktitle = {Virtuelle Pathologietage},
  title     = {Comparison of Sectioning-free Multiphoton Histology to H&E FFPE imaging},
  year      = {2021},
  keywords  = {AG-Huber_NL},
}

@Conference{Strauch2021,
  author    = {M. Strauch, J.P. Kolb, C. Rose, N. Merg, J. Hundt, C. Kümpers, S. Perner, S. Karpf and R. Huber},
  booktitle = {33rd Congress of the ESP},
  title     = {Quick sectioning-free H&E imaging of bulk tissue using multiphoton microscopy},
  year      = {2021},
  keywords  = {AG-Huber_NL},
}

@article{Pfeiffer:20,
author = {T. Pfeiffer, M. G\"{o}b, W. Draxinger, S. Karpf, J.P. Kolb and R. Huber},
journal = {Biomed. Opt. Express},
keywords = {AG-Huber_OCT; High speed imaging; Image quality; Optical coherence tomography; Swept lasers; Swept sources; Systems design},
number = {11},
pages = {6799--6811},
publisher = {OSA},
title = {Flexible A-scan rate MHz-OCT: efficient computational downscaling by coherent averaging},
volume = {11},
month = {Nov},
year = {2020},
doi = {10.1364/BOE.402477},
abstract = {In order to realize adjustable A-scan rates of fast optical coherence tomography (OCT) systems, we investigate averaging of OCT image data acquired with a MHz-OCT system based on a Fourier Domain Mode Locked (FDML) laser. Increased system sensitivity and image quality can be achieved with the same system at the cost of lower imaging speed. Effectively, the A-scan rate can be reduced in software by a freely selectable factor. We demonstrate a detailed technical layout of the strategies necessary to achieve efficient coherent averaging. Since there are many new challenges specific to coherent averaging in swept source MHz-OCT, we analyze them point by point and describe the appropriate solutions. We prove that coherent averaging is possible at MHz OCT-speed without special interferometer designs or digital phase stabilization. We find, that in our system up to \&\#x223C;100x coherent averaging is possible while achieving a sensitivity increase close to the ideal values. This corresponds to a speed reduction from 3.3 MHz to 33 kHz and a sensitivity gain of 20 dB. We show an imaging comparison between coherent and magnitude averaging of a human finger knuckle joint in vivo with 121\&\#x00A0;dB sensitivity for the coherent case. Further, the benefits of computational downscaling in low sensitivity MHz-OCT systems are analyzed.},
}

@InProceedings{Strauch2020,
  author    = {M. Strauch, J.P. Kolb, D. Weng, M. Wacker, W. Draxinger, N. Merg, J. Hundt, S. Karpf and R. Huber},
  booktitle = {104. Jahrestagung der Deutschen Gesellschaft fuer Pathologie},
  title     = {Two-photon microscopy for sectioning-free virtual {H&E} imaging},
URL = {https://www.pathologie-dgp.de/media/Dgp/user_upload/Verhandlungsband_2020_final__kompr._.pdf},
  year      = {2020},
  keywords  = {AG-Huber_NL},
}

@InProceedings{Strauch2020a,
  author    = {M. Strauch, J.P. Kolb, N. Merg, J. Hundt, S. Karpf and R. Huber},
  booktitle = {32nd Congress of the ESP and XXXIII International Congress of the IAP},
  title     = {Evaluation of two-photon fluorescence microscopy for sectioning-free {H&E} imaging of different tissues},
  year      = {2020},
  keywords  = {AG-Huber_NL},
}

@INPROCEEDINGS{8872571,
  author={Weng, Daniel and Hakert, Hubertus and Blömker, Torben and Kolb, Jan Philip and Strauch, Matthias and Eibl, Matthias and Lamminger, Philipp and Karpf, Sebastian and Huber, Robert},
  booktitle={2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)}, 
  title={Sub-Nanosecond Pulsed Fiber Laser for 532nm Two-Photon Excitation Fluorescence (TPEF) Microscopy of UV Transitions}, 
  year={2019},
  volume={},
  number={},
  pages={1-1},
  abstract={Summary form only given. Two-photon microscopy is a powerful technique for in vivo imaging, due to its high penetration depth and axial sectioning. Usually excitation wavelengths in the near infrared are used. However, most fluorescence techniques for live cell imaging require labeling with exogenous fluorophores. It has been shown that shorter wavelengths can be used to excite the autofluorescence of endogenous proteins, e.g. tryptophan. Recently we demonstrated a fully fiber-based laser source built around a directly modulated, ytterbium amplified 1064 nm laser diode with sub-nanosecond pulses for two-photon imaging [2]. The overall system enables to capture high-speed fluorescence lifetime imaging (FLIM) with single pulse excitation. Here, we extend the spectral range of this laser source by frequency doubling it to 532nm to achieve two-photon excited fluorescence microscopy (TPM) in the ultraviolett (UV) range to harness endogenous autofluorescence. In this presentation we explore first TPM results of tryptophan to investigate signal levels and fi delity before transitioning to biological tissues. It has been shown that TPM of endogenous tryptophan can be used to visualize immune system activity in vivo. Our laser source could be a cheap, flexible and fiber-based alternative to the OPO-based Ti:Sa Lasers currently employed. The basic concept of our design is to shift the wavelength of the pulsed fiber-based master oscillator power amplifier (MOPA) by second-harmonic generation (SHG) using phase-matching in a KTP crystal. This generates a coherent output at 532nm at a maximal peak power of 500W. We achieved a maximum conversion efficiency of about 17%. After the SHG module, the 532nm light is coupled into a single-mode fiber and delivered to a home built microscope. A 40x microscope objective is used to excite the sample and epi-collect the fluorescence. The fluorescence is recorded on a UV-enhanced photomultiplier tube (PMT). For a proof of concept measurement, crystalized tryptophan was imaged. Here we show signals of pure tryptophan, with laser parameters of 1MHz repetition rate and 100ps pulse duration. We used spectral bandpass fi lters in order to detect only fluorescence signal, however, from crystalized tryptophan we observed an unexpected short lifetime. We have recently shown that we can shift our laser output from 1064nm to longer wavelengths. By shifting to 1180nm and frequency doubling to 590nm a more efficient fluorescence excitation of tryptophan can be achieved. In the future we aim at in vivo imaging with our setup.},
  keywords={},
  doi={10.1109/CLEOE-EQEC.2019.8872571},
  ISSN={},
  month={June}}

@inproceedings{10.1117/12.2507866,
author = {Jan Philip Kolb and Daniel Weng and Hubertus Hakert and Matthias Eibl and Wolfgang Draxinger and Tobias Meyer and Thomas Gottschall and Ralf  Brinkmann and Reginald Birngruber and J{\"u}rgen Popp and Jens Limpert and Sebastian Nino Karpf and Robert Huber},
title = {{Virtual HE histology by fiber-based picosecond two-photon microscopy}},
volume = {10882},
booktitle = {Multiphoton Microscopy in the Biomedical Sciences XIX},
editor = {Ammasi Periasamy and Peter T. C. So and Karsten K{\"o}nig},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {108822F},
abstract = {Two-Photon Microscopy (TPM) can provide three-dimensional morphological and functional contrast in vivo. Through proper staining, TPM can be utilized to create virtual, HE equivalent images and thus can improve throughput in histology-based applications. We previously reported on a new light source for TPM that employs a compact and robust fiber-amplified, directly modulated laser. This laser is pulse-to-pulse wavelength switchable between 1064 nm, 1122 nm, and 1186 nm with an adjustable pulse duration from 50ps to 5ns and arbitrary repetition rates up to 1MHz at kW-peak powers. Despite the longer pulse duration, it can achieve similar average signal levels compared to fs-setups by lowering the repetition rate to achieve similar cw and peak power levels. The longer pulses lead to a larger number of photons per pulse, which yields single shot fluorescence lifetime measurements (FLIM) by applying a fast 4 GSamples/s digitizer. In the previous setup, the wavelengths were limited to 1064 nm and longer. Here, we use four wave mixing in a non-linear photonic crystal fiber to expand the wavelength range down to 940 nm. This wavelength is highly suitable for imaging green fluorescent proteins in neurosciences and stains such as acridine orange (AO), eosin yellow (EY) and sulforhodamine 101 (SR101) used for histology applications. In a more compact setup, we also show virtual HE histological imaging using a direct 1030 nm fiber MOPA.},
keywords = {Multiphoton Microscopy, Four Wave Mixing, FWM, Histology, Laser, Non Linear Microscopy, Two Photon Microscopy, JenLab Young Investigator Award},
year = {2019},
doi = {10.1117/12.2507866},
URL = {https://doi.org/10.1117/12.2507866}
}

@article{karpf2019-2,
   author = {Karpf, S and Jalali, B},
   title = {Frequency-doubled FDML-MOPA laser in the visible},
   journal = {Opt Lett 44(24)},
   keywords = {},
   pages = {5913-5916},
   DOI = {10.1364/OL.44.005913},
   
   year = {2019},
   type = {Journal Article}
}

@InProceedings{Strauch2019,
  author    = {Strauch, Matthias and Kolb, Jan Philip and Weng, Daniel and Wacker, Melanie and Draxinger, Wolfgang and Karpf, Sebastian and Huber, Robert},
  booktitle = {31st Congress of the ESP},
  title     = {Sectioning-Free Virtual H&E Imaging of Tissue Samples with Two-Photon Microscopy},
  year      = {2019},
  keywords  = {AG-Huber_NL},
}

@article{Karpf2019,
   author = {Karpf, S and Jalali, B },
   title = {Fourier-domain mode-locked laser combined with a master-oscillator power amplifier architecture},
   journal = {J Opt Lett},
   URL = {https://doi.org/10.1364/OL.44.001952},
   pages = {1952-1955},
   ISSN = {1539-4794},
   year = {2019},
 keywords = {},
   type = {Journal Article}
}

@article{Eibl2018,
  doi = {10.1364/boe.9.006273},
  url = {https://doi.org/10.1364/boe.9.006273},
  year = {2018},
  month = nov,
  publisher = {The Optical Society},
  volume = {9},
  number = {12},
  pages = {6273},
  author = {Matthias Eibl and Daniel Weng and Hubertus Hakert and Jan Philip Kolb and Tom Pfeiffer and Jennifer E. Hundt and Robert Huber and Sebastian Karpf},
  title = {Wavelength agile multi-photon microscopy with a fiber amplified diode laser},
  journal = {Biomedical Optics Express}
}

@article{Eibl:17,
author = {Matthias Eibl and Sebastian Karpf and Hubertus Hakert and Torben Bl\"{o}mker and Jan Philip Kolb and Christian Jirauschek and Robert Huber},
journal = {Opt. Lett.},
keywords = {Lasers, fiber; Lasers, Raman; Nonlinear optics, four-wave mixing; Scattering, stimulated Raman; Lasers, ytterbium ; Fiber lasers; Master oscillator power amplifiers; Nanosecond pulses; Raman scattering; Stimulated Brillouin scattering; Wavelength conversion},
number = {21},
pages = {4406--4409},
publisher = {Optica Publishing Group},
title = {Pulse-to-pulse wavelength switching of a nanosecond fiber laser by four-wave mixing seeded stimulated Raman amplification},
volume = {42},
month = {Nov},
year = {2017},
url = {https://opg.optica.org/ol/abstract.cfm?URI=ol-42-21-4406},
doi = {10.1364/OL.42.004406},
abstract = {We report on a multi-color fiber laser based on four-wave mixing (FWM) and stimulated Raman scattering (SRS), delivering rapidly wavelength switchable narrowband output at 1064, 1122, and 1186\&\#x00A0;nm. High-power pulses from a nanosecond pulsed fiber master oscillator power amplifier at 1064\&\#x00A0;nm are combined with 1122\&\#x00A0;nm of seed light for Raman amplification at the first Stokes order in a standard single-mode fiber. With increasing power, we observe a narrowband spectral component at 1186\&\#x00A0;nm, without any additional seed or resonator at this wavelength. We analyze this occurrence of a narrowband second Stokes order both experimentally and theoretically and suggest it is a result of FWM seeding of the SRS amplification in the fiber. We demonstrate that the wavelength shifting can be controlled electronically within microseconds for very rapid and even pulse-to-pulse wavelength changes. This wavelength conversion method can extend the spectral coverage of single-wavelength fiber lasers for biomedical imaging.},
}

@inproceedings{10.1117/12.2286035,
author = {Matthias Eibl and Sebastian Karpf and Hubertus Hakert and Daniel Weng and Tom Pfeiffer and Jan Philip Kolb and Robert Huber},
title = {{Single pulse two-photon fluorescence lifetime imaging (SP-FLIM) with MHz pixel rate and an all fiber based setup }},
volume = {10414},
booktitle = {Advances in Microscopic Imaging},
editor = {Emmanuel Beaurepaire and Francesco Saverio Pavone and Peter T. C. So},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {1041403},
abstract = {Newly developed microscopy methods have the goal to give researches in bio-molecular science a better understanding of processes ongoing on a cellular level. Especially two-photon excited fluorescence (TPEF) microscopy is a readily applied and widespread modality. Compared to one photon fluorescence imaging, it is possible to image not only the surface but also deeper lying structures. Together with fluorescence lifetime imaging (FLIM), which provides information on the chemical composition of a specimen, deeper insights on a molecular level can be gained. However, the need for elaborate light sources for TPEF and speed limitations for FLIM hinder an even wider application. In this contribution, we present a way to overcome this limitations by combining a robust and inexpensive fiber laser for nonlinear excitation with a fast analog digitization method for rapid FLIM imaging. The applied sub nanosecond pulsed laser source is perfectly suited for fiber delivery as typically limiting non-linear effects like self-phase or cross-phase modulation (SPM, XPM) are negligible. Furthermore, compared to the typically applied femtosecond pulses, our longer pulses produce much more fluorescence photons per single shot. In this paper, we show that this higher number of fluorescence photons per pulse combined with a high analog bandwidth detection makes it possible to not only use a single pulse per pixel for TPEF imaging but also to resolve the exponential time decay for FLIM. To evaluate our system, we acquired FLIM images of a dye solution with single exponential behavior to assess the accuracy of our lifetime determination and also FLIM images of a plant stem at a pixel rate of 1 MHz to show the speed performance of our single pulse two-photon FLIM (SP-FLIM) system.},
keywords = {Nonlinear microscopy, Fluorescence microscopy, Fiber optics imaging, Lifetime-based sensing, Lasers, fiber, Nonlinear optics, fibers},
year = {2017},
doi = {10.1117/12.2286035},
URL = {https://doi.org/10.1117/12.2286035}
}

@inproceedings{10.1117/12.2287947,
author = {Hubertus Hakert and Matthias Eibl and Sebastian Karpf and Robert Huber},
title = {{Sparse-sampling with time-encoded (TICO) stimulated Raman scattering for fast image acquisition}},
volume = {10414},
booktitle = {Advances in Microscopic Imaging},
editor = {Emmanuel Beaurepaire and Francesco Saverio Pavone and Peter T. C. So},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {1041408},
abstract = {Modern biomedical imaging modalities aim to provide researchers a multimodal contrast for a deeper insight into a
specimen under investigation. A very promising technique is stimulated Raman scattering (SRS) microscopy, which can
unveil the chemical composition of a sample with a very high specificity. Although the signal intensities are enhanced
manifold to achieve a faster acquisition of images if compared to standard Raman microscopy, there is a trade-off between
specificity and acquisition speed. Commonly used SRS concepts either probe only very few Raman transitions as the
tuning of the applied laser sources is complicated or record whole spectra with a spectrometer based setup. While the first
approach is fast, it reduces the specificity and the spectrometer approach records whole spectra -with energy differences
where no Raman information is present-, which limits the acquisition speed. Therefore, we present a new approach based
on the TICO-Raman concept, which we call sparse-sampling. The TICO-sparse-sampling setup is fully electronically
controllable and allows probing of only the characteristic peaks of a Raman spectrum instead of always acquiring a whole
spectrum. By reducing the spectral points to the relevant peaks, the acquisition time can be greatly reduced compared to a
uniformly, equidistantly sampled Raman spectrum while the specificity and the signal to noise ratio (SNR) are maintained.
Furthermore, all laser sources are completely fiber based. The synchronized detection enables a full resolution of the
Raman signal, whereas the analogue and digital balancing allows shot noise limited detection. First imaging results with
polystyrene (PS) and polymethylmethacrylate (PMMA) beads confirm the advantages of TICO sparse-sampling. We
achieved a pixel dwell time as low as 35 μs for an image differentiating both species. The mechanical properties of the
applied voice coil stage for scanning the sample currently limits even faster acquisition.},
keywords = {nonlinear microscopy, fiber optics imaging, stimulated raman scattering microscopy, time encoded, sparse sampling, Raman spectroscopy , Fourier Domain Mode Locked Laser, FDML, Lasers, fiber},
year = {2017},
doi = {10.1117/12.2287947},
URL = {https://doi.org/10.1117/12.2287947}
}

@article{Karpf2017,
   author = {Karpf, Sebastian and Eibl, Matthias and Wieser, Wolfgang and Klein, Thomas and Huber, Robert},
   title = {Shot-Noise Limited Time-Encoded Raman Spectroscopy},
   journal = {Journal of Spectroscopy},
   volume = {2017},
   pages = {1-6},
   url = {https://doi.org/10.1155/2017/9253475},
   year = {2017},
keywords = {AG-Huber_NL},
   type = {Journal Article}
}

@inproceedings{10.1117/12.2251965,
author = {Matthias Eibl and Sebastian Karpf and Hubertus Hakert and Daniel Weng and Torben Bl{\"o}mker and Robert Huber},
title = {{Pulse-to-pulse wavelength switching of diode based fiber laser for multi-color multi-photon imaging}},
volume = {10083},
booktitle = {Fiber Lasers XIV: Technology and Systems},
editor = {Craig A. Robin and Ingmar Hartl},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {100831C},
abstract = {We present an entirely fiber based laser source for non-linear imaging with a novel approach for multi-color excitation. The high power output of an actively modulated and amplified picosecond fiber laser at 1064 nm is shifted to longer wavelengths by a combination of four-wave mixing and stimulated Raman scattering. By combining different fiber types and lengths, we control the non-linear wavelength conversion in the delivery fiber itself and can switch between 1064 nm, 1122 nm, and 1186 nm on-the-fly by tuning the pump power of the fiber amplifier and modulate the seed diodes. This is a promising way to enhance the applicability of short pulsed laser diodes for bio-molecular non-linear imaging by reducing the spectral limitations of such sources. In comparison to our previous work [1, 2], we show for the first time two-photon imaging with the shifted wavelengths and we demonstrate pulse-to-pulse switching between the different wavelengths without changing the configuration.},
keywords = {stimulated raman scattering, two-photon imaging, fiber amplifier, four-wave-mixing, wavelength conversion, non-linear imaging},
year = {2017},
doi = {10.1117/12.2251965},
URL = {https://doi.org/10.1117/12.2251965}
}

@inproceedings{10.1117/12.2250831,
author = {Matthias Eibl and Sebastian Karpf and Hubertus Hakert and Daniel Weng and Robert Huber},
title = {{Two-photon-excited fluorescence (TPEF) and fluorescence lifetime imaging (FLIM) with sub-nanosecond pulses and a high analog bandwidth signal detection}},
volume = {10069},
booktitle = {Multiphoton Microscopy in the Biomedical Sciences XVII},
editor = {Ammasi Periasamy and Peter T. C. So and Karsten K{\"o}nig and Xiaoliang S. Xie},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {100691F},
abstract = {Two-photon excited fluorescence (TPEF) microscopy and fluorescence lifetime imaging (FLIM) are powerful imaging techniques in bio-molecular science. The need for elaborate light sources for TPEF and speed limitations for FLIM, however, hinder an even wider application. We present a way to overcome this limitations by combining a robust and inexpensive fiber laser for nonlinear excitation with a fast analog digitization method for rapid FLIM imaging. The applied sub nanosecond pulsed laser source is synchronized to a high analog bandwidth signal detection for single shot TPEF- and single shot FLIM imaging. The actively modulated pulses at 1064nm from the fiber laser are adjustable from 50ps to 5ns with kW of peak power. At a typically applied pulse lengths and repetition rates, the duty cycle is comparable to typically used femtosecond pulses and thus the peak power is also comparable at same cw-power. Hence, both types of excitation should yield the same number of fluorescence photons per time on average when used for TPEF imaging. However, in the 100ps configuration, a thousand times more fluorescence photons are generated per pulse. In this paper, we now show that the higher number of fluorescence photons per pulse combined with a high analog bandwidth detection makes it possible to not only use a single pulse per pixel for TPEF imaging but also to resolve the exponential time decay for FLIM. To evaluate the performance of our system, we acquired FLIM images of a Convallaria sample with pixel rates of 1 MHz where the lifetime information is directly measured with a fast real time digitizer. With the presented results, we show that longer pulses in the many-10ps to nanosecond regime can be readily applied for TPEF imaging and enable new imaging modalities like single pulse FLIM.},
keywords = {FLIM, TPEF, fiber laser, endoscope, MOPA, Nonlinear microscopy, Fluorescence microscopy, Lifetime-based sensing},
year = {2017},
doi = {10.1117/12.2250831},
URL = {https://doi.org/10.1117/12.2250831}
}

@article{Eibl:17,
author = {Matthias Eibl and Sebastian Karpf and Daniel Weng and Hubertus Hakert and Tom Pfeiffer and Jan Philip Kolb and Robert Huber},
journal = {Biomed. Opt. Express},
keywords = {Fiber optics imaging; Nonlinear optics, fibers; Lasers, fiber; Lifetime-based sensing; Fluorescence microscopy; Nonlinear microscopy; Fourier domain mode locking; Image quality; Imaging techniques; Laser sources; Pulsed fiber lasers; Three dimensional sensing},
number = {7},
pages = {3132--3142},
publisher = {Optica Publishing Group},
title = {Single pulse two photon fluorescence lifetime imaging (SP-FLIM) with MHz pixel rate},
volume = {8},
month = {Jul},
year = {2017},
url = {https://opg.optica.org/boe/abstract.cfm?URI=boe-8-7-3132},
doi = {10.1364/BOE.8.003132},
abstract = {Two-photon-excited fluorescence lifetime imaging microscopy (FLIM) is a chemically specific 3-D sensing modality providing valuable information about the microstructure, composition and function of a sample. However, a more widespread application of this technique is hindered by the need for a sophisticated ultra-short pulse laser source and by speed limitations of current FLIM detection systems. To overcome these limitations, we combined a robust sub-nanosecond fiber laser as the excitation source with high analog bandwidth detection. Due to the long pulse length in our configuration, more fluorescence photons are generated per pulse, which allows us to derive the lifetime with a single excitation pulse only. In this paper, we show high quality FLIM images acquired at a pixel rate of 1 MHz. This approach is a promising candidate for an easy-to-use and benchtop FLIM system to make this technique available to a wider research community.},
}

@article{Karpf:16,
author = {Sebastian Karpf and Matthias Eibl and Benjamin Sauer and Fred Reinholz and Gereon H\"{u}ttmann and Robert Huber},
journal = {Biomed. Opt. Express},
keywords = {Fiber optics imaging; Nonlinear optics, fibers; Lasers, fiber; Fluorescence microscopy; Nonlinear microscopy; Femtosecond pulses; In vivo imaging; Laser sources; Nanosecond pulses; Optical systems; Ultrafast lasers},
number = {7},
pages = {2432--2440},
publisher = {Optica Publishing Group},
title = {Two-photon microscopy using fiber-based nanosecond excitation},
volume = {7},
month = {Jul},
year = {2016},
url = {https://opg.optica.org/boe/abstract.cfm?URI=boe-7-7-2432},
doi = {10.1364/BOE.7.002432},
abstract = {Two-photon excitation fluorescence (TPEF) microscopy is a powerful technique for sensitive tissue imaging at depths of up to 1000 micrometers. However, due to the shallow penetration, for in vivo imaging of internal organs in patients beam delivery by an endoscope is crucial. Until today, this is hindered by linear and non-linear pulse broadening of the femtosecond pulses in the optical fibers of the endoscopes. Here we present an endoscope-ready, fiber-based TPEF microscope, using nanosecond pulses at low repetition rates instead of femtosecond pulses. These nanosecond pulses lack most of the problems connected with femtosecond pulses but are equally suited for TPEF imaging. We derive and demonstrate that at given cw-power the TPEF signal only depends on the duty cycle of the laser source. Due to the higher pulse energy at the same peak power we can also demonstrate single shot two-photon fluorescence lifetime measurements.},
}

@inproceedings{10.1117/12.2183822,
author = {Matthias Eibl and Sebastian Karpf and Wolfgang Wieser and Thomas Klein and Robert Huber},
title = {{Hyperspectral stimulated Raman microscopy with two fiber laser sources}},
volume = {9536},
booktitle = {Advanced Microscopy Techniques IV; and Neurophotonics II},
editor = {Emmanuel Beaurepaire and Peter T. C. So and Francesco Pavone and Elizabeth M. Hillman},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {953604},
abstract = {A fast all fiber based setup for stimulated Raman microscopy based on a rapidly wavelength swept cw-laser is presented. The applied Fourier domain mode locked (FDML) laser is a fiber ring laser, providing a continuously changing wavelength output over time. This fast swept source allows us to rapidly change the wavelength and, thereby the energy difference with respect to a single color pump laser. The pump laser is a master oscillator power amplifier based on a fiber amplified laser diode and a Raman shifter. By controlled variation of the relative timing between probe and pump laser with an arbitrary waveform generator, the Raman signals are encoded in time and they are directly acquired with a synchronized, fast analog-to-digital converter. This setup is capable of acquiring rapidly high resolution spectra (up to 0.5 cm<sup>-1</sup>) with shot noise limited sensitivity over a broadband (750 cm<sup>-1</sup> to 3150 cm<sup>-1</sup>) spectral region. Here, we show the performance of this system for imaging in the CH-stretch region around 3000 cm<sup>-1</sup> and in the fingerprint region around 1600 cm<sup>-1</sup>. We present hyperspectral images of a plant stem slice with molecular contrast of lignin and a lipid representative as well as images of PS (polystyrene) and PMMA (poly(methyl methacrylate) beads with an acquisition speed of 18 &mu;s per spectral point.},
keywords = {stimulated Raman, multiphoton, microscopy, coherent Raman, fiber laser, FDML, TICO, hyperspectral},
year = {2015},
doi = {10.1117/12.2183822},
URL = {https://doi.org/10.1117/12.2183822}
}

@inproceedings{10.1117/12.2183854,
author = {Sebastian Karpf and Matthias Eibl and Robert Huber},
title = {{Nanosecond two-photon excitation fluorescence imaging with a multi color fiber MOPA laser}},
volume = {9536},
booktitle = {Advanced Microscopy Techniques IV; and Neurophotonics II},
editor = {Emmanuel Beaurepaire and Peter T. C. So and Francesco Pavone and Elizabeth M. Hillman},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {953616},
abstract = {A system is presented that uses a fiber based Master Oscillator Power Amplifier (MOPA) with nanosecond-range pulses for two-photon excitation fluorescence (TPEF) imaging. The robust laser in the extended near infrared is based on an actively modulated electro-optical modulator (EOM), enabling free synchronization of the pulses to any other light source or detection unit. Pulses with a freely programmable duration between 0.4 and 10 ns are generated and then amplified to up to kilowatts of peak power with ytterbium doped fiber amplifiers (YDFA). Since we achieve peak power and duty cycles comparable to standard femto- and picosecond setups, the TPEF signal levels are similar, but realized with a robust and inexpensive fiber-based setup. The delivery fiber is further used as an optional, electronically controllable Raman shifter to effectively shift the 1064 nm light to 1122 nm and to 1186 nm. This allows imaging of a manifold of fluorophores, like e.g. TexasRed, mCherry, mRaspberry and many more. We show TPEF imaging of the autofluorescence of plant leaves of moss and algae, acquired in epi-direction. This modular laser unit can be integrated into existing systems as either a fiber-based, alignment free excitation laser or an extension for multi-modal imaging.},
keywords = {multi-photon imaging, TPEF, MOPA, TPA, fiber laser, Raman shifter, non-linear imaging, multi-modal imaging},
year = {2015},
doi = {10.1117/12.2183854},
URL = {https://doi.org/10.1117/12.2183854}
}

@inproceedings{10.1117/12.2183859,
author = {Sebastian Karpf and Matthias Eibl and Wolfgang Wieser and Thomas Klein and Robert Huber},
title = {{Time-encoded Raman scattering (TICO-Raman) with Fourier domain mode locked (FDML) lasers}},
volume = {9541},
booktitle = {Optical Coherence Imaging Techniques and Imaging in Scattering Media},
editor = {Brett E. Bouma and Maciej Wojtkowski},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {95410F},
abstract = {We present a new concept for performing stimulated Raman spectroscopy and microscopy by employing rapidly wavelength swept Fourier Domain Mode locked (FDML) lasers [1]. FDML lasers are known for fastest imaging in swept-source optical coherence tomography [2, 3]. We employ this continuous and repetitive wavelength sweep to generate broadband, high resolution stimulated Raman spectra with a new, time-encoded (TICO) concept [4]. This allows for encoding and detecting the stimulated Raman gain on the FDML laser intensity directly in time. Therefore we use actively modulated pump lasers, which are electronically synchronized to the FDML laser, in combination with a fast analog-to-digital converter (ADC) at 1.8 GSamples/s. We present hyperspectral Raman images with color-coded, molecular contrast.},
keywords = {swept lasers, FDML, TICO-Raman, fiber lasers, stimulated Raman microscopy, Raman spectroscopy, molecular contrast, multi-modal imaging},
year = {2015},
doi = {10.1117/12.2183859},
URL = {https://doi.org/10.1117/12.2183859}
}

@Article{HU_2015_Karpf_a,
  Title                    = {A Time-Encoded Technique for fibre-based hyperspectral broadband stimulated Raman microscopy},
  Author                   = {Karpf, Sebastian and Eibl, Matthias and Wieser, Wolfgang and Klein, Thomas and Huber, Robert},
  Journal                  = {Nature Communications},
  Year                     = {2015},
  Volume = {6},
  pages = {6784 1--6},
keywords = {AG-Huber_NL},
  Doi                      = {10.1038/ncomms7784}
}

@article{Wieser:14,
author = {Wolfgang Wieser and Wolfgang Draxinger and Thomas Klein and Sebastian Karpf and Tom Pfeiffer and Robert Huber},
journal = {Biomed. Opt. Express},
keywords = {Optical coherence tomography; Lasers, tunable; Optical coherence tomography; Endoscopic imaging; Full field optical coherence tomography; Functional imaging; Image quality; Ophthalmic imaging; Vertical cavity surface emitting lasers},
number = {9},
pages = {2963--2977},
publisher = {Optica Publishing Group},
title = {High definition live 3D-OCT in vivo: design and evaluation of a 4D OCT engine with 1 GVoxel/s},
volume = {5},
month = {Sep},
year = {2014},
url = {https://opg.optica.org/boe/abstract.cfm?URI=boe-5-9-2963},
doi = {10.1364/BOE.5.002963},
abstract = {We present a 1300 nm OCT system for volumetric real-time live OCT acquisition and visualization at 1 billion volume elements per second. All technological challenges and problems associated with such high scanning speed are discussed in detail as well as the solutions. In one configuration, the system acquires, processes and visualizes 26 volumes per second where each volume consists of 320 x 320 depth scans and each depth scan has 400 usable pixels. This is the fastest real-time OCT to date in terms of voxel rate. A 51 Hz volume rate is realized with half the frame number. In both configurations the speed can be sustained indefinitely. The OCT system uses a 1310 nm Fourier domain mode locked (FDML) laser operated at 3.2 MHz sweep rate. Data acquisition is performed with two dedicated digitizer cards, each running at 2.5 GS/s, hosted in a single desktop computer. Live real-time data processing and visualization are realized with custom developed software on an NVidia GTX 690 dual graphics processing unit (GPU) card. To evaluate potential future applications of such a system, we present volumetric videos captured at 26 and 51 Hz of planktonic crustaceans and skin.},
}

@Article{HU_2014_Karpf_a,
  Title                    = {{Time-Encoded Raman: Fiber-based, hyperspectral, broadband stimulated Raman microscopy}},
  Author                   = {Karpf, Sebastian and Eibl, Matthias and Wieser, Wolfgang and Klein, Thomas and Huber, Robert},
  journal = {ArXiv e-prints},
  Year                     = {2014},
  Archiveprefix            = {arXiv},
  Arxivid                  = {1405.4181},
  Eprint                   = {1405.4181},
keywords = {AG-Huber_NL},
  Url                      = {http://arxiv.org/abs/1405.4181}
}

@inproceedings{Eibl:14,
author = {Matthias Eibl and Sebastian Karpf and Wolfgang Wieser and Thomas Klein and Robert Huber},
booktitle = {CLEO: 2014},
journal = {CLEO: 2014},
keywords = {Lasers, tunable; Scattering, stimulated Raman; Spectroscopy, Raman; Laser light; Laser sources; Master oscillator power amplifiers; Raman spectroscopy; Self phase modulation; Stimulated Raman scattering},
pages = {ATu3P.4},
publisher = {Optica Publishing Group},
title = {Broadband, High Resolution Stimulated Raman Spectroscopy with Rapidly Wavelength Swept cw-Lasers},
year = {2014},
url = {https://opg.optica.org/abstract.cfm?URI=CLEO_AT-2014-ATu3P.4},
doi = {10.1364/CLEO_AT.2014.ATu3P.4},
abstract = {A fast all fiber based setup for stimulated Raman spectroscopy with a rapidly wavelength swept cw-laser is presented. It enables flexible acquisition of broadband (750 cm{\textminus}1 to 3150 cm{\textminus}1) spectra with high resolution (0.5 cm{\textminus}1).},
}

@inproceedings{Karpf:14,
author = {Sebastian Karpf and Matthias Eibl and Wolfgang Wieser and Thomas Klein and Robert Huber},
booktitle = {CLEO: 2014},
journal = {CLEO: 2014},
keywords = {Lasers, tunable; Scattering, stimulated Raman; Raman microscopy; Biological imaging; Medical imaging; Optical coherence tomography; Raman microscopy; Raman scattering; Swept lasers},
pages = {SM3P.3},
publisher = {Optica Publishing Group},
title = {Hyperspectral Stimulated Raman Microscopy with Fiber-based, Rapidly Wavelength Swept cw-Lasers},
year = {2014},
url = {https://opg.optica.org/abstract.cfm?URI=CLEO_SI-2014-SM3P.3},
doi = {10.1364/CLEO_SI.2014.SM3P.3},
abstract = {A hyperspectral stimulated Raman microscopy system using rapidly wavelength swept lasers is presented. Imaging of biological samples with shot noise limited detection is demonstrated with the fiber based setup.},
}

@inproceedings{Karpf:13,
author = {Sebastian Karpf and Matthias Eibl and Wolfgang Wieser and Thomas Klein and Robert Huber},
booktitle = {CLEO: 2013},
journal = {CLEO: 2013},
keywords = {Lasers, fiber; Scattering, stimulated Raman; Spectroscopy, Raman; Fourier domain mode locking; Lasers; Optical coherence tomography; Raman lasers; Raman spectroscopy; Swept lasers},
pages = {CTu2H.5},
publisher = {Optica Publishing Group},
title = {FDML Raman: High Speed, High Resolution Stimulated Raman Spectroscopy with Rapidly Wavelength Swept Lasers},
year = {2013},
url = {https://opg.optica.org/abstract.cfm?URI=CLEO_SI-2013-CTu2H.5},
doi = {10.1364/CLEO_SI.2013.CTu2H.5},
abstract = {An all fiber based system for high speed, high resolution Raman sensing is presented. The system is based on a wavelength swept Fourier Domain Mode Locked (FDML) laser for the detection of the Raman signal.},
}

@INPROCEEDINGS{6801995,
  author={Karpf, Sebastian and Eibl, Matthias and Wieser, Wolfgang and Klein, Thomas and Huber, Robert},
  booktitle={2013 Conference on Lasers & Electro-Optics Europe & International Quantum Electronics Conference CLEO EUROPE/IQEC}, 
  title={FDML Raman: New high resolution SRS with ultra broadband spectral coverage}, 
  year={2013},
  volume={},
  number={},
  pages={1-1},
  doi={10.1109/CLEOE-IQEC.2013.6801995}}

@article{Wieser:12,
author = {Wolfgang Wieser and Thomas Klein and Desmond C. Adler and Francois Tr\'{e}panier and Christoph M. Eigenwillig and Sebastian Karpf and Joseph M. Schmitt and Robert Huber},
journal = {Biomed. Opt. Express},
keywords = {Optical coherence tomography; Lasers, tunable; Optical coherence tomography; Amplified spontaneous emission; Crystalline lens; Gastrointestinal imaging; High speed imaging; Image quality; Three dimensional imaging},
number = {10},
pages = {2647--2657},
publisher = {Optica Publishing Group},
title = {Extended coherence length megahertz FDML and its application for anterior segment imaging},
volume = {3},
month = {Oct},
year = {2012},
url = {https://opg.optica.org/boe/abstract.cfm?URI=boe-3-10-2647},
doi = {10.1364/BOE.3.002647},
abstract = {We present a 1300 nm Fourier domain mode locked (FDML) laser for optical coherence tomography (OCT) that combines both, a high 1.6 MHz wavelength sweep rate and an ultra-long instantaneous coherence length for rapid volumetric deep field imaging. By reducing the dispersion in the fiber delay line of the FDML laser, the instantaneous coherence length and hence the available imaging range is approximately quadrupled compared to previously published MHz-FDML setups, the imaging speed is increased by a factor of 16 compared to previous extended coherence length results. We present a detailed characterization of the FDML laser performance. We demonstrate for the first time MHz-OCT imaging of the anterior segment of the human eye. The OCT system provides enough imaging depth to cover the whole range from the top surface of the cornea down to the crystalline lens.},
}

@inproceedings{Wieser:12,
author = {Wolfgang Wieser and Thomas Klein and Desmond C. Adler and Francois Tr\'{e}panier and Sebastian Karpf and Christoph M Eigenwillig and Joseph M. Schmitt and Robert Huber},
booktitle = {Conference on Lasers and Electro-Optics 2012},
journal = {Conference on Lasers and Electro-Optics 2012},
keywords = {Optical coherence tomography; Lasers, tunable; Optical coherence tomography; Fiber Bragg gratings; Fourier domain mode locking; Image quality; Laser modes; Mode locking; Optical coherence tomography},
pages = {JTh3J.2},
publisher = {Optica Publishing Group},
title = {Dispersion Compensated Megahertz FDML Laser for Imaging of the Anterior Segment},
year = {2012},
url = {https://opg.optica.org/abstract.cfm?URI=CLEO_AT-2012-JTh3J.2},
doi = {10.1364/CLEO_AT.2012.JTh3J.2},
abstract = {We present a Fourier domain mode locked laser at 1.6 MHz scan rate with greatly improved coherence length by reducing the laser cavity dispersion and the application of this laser in optical coherence tomography.},
}