Philipp Lamminger

@inproceedings{10.1117/12.3046222,
author = {Sazgar Burhan and Berenice Schulte and Madita G{\"o}b and Awanish Pratap Singh and Bayan Mustafa and Simon Lotz and Wolfgang Draxinger and Philipp Lamminger and Yasmeine Saker and Tim Eixmann and Martin Ahrens and Marvin Heimke and Tillmann Heinze and Thilo Wedel and Maik Rahlves and Mark Ellrichmann and Robert Huber},
title = {{Switchable lateral resolution real-time MHz-OCT rectoscopy for enhanced colorectal disease diagnosis}},
volume = {13305},
booktitle = {Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XXIX},
editor = {Rainer A. Leitgeb and Yoshiaki Yasuno},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {1330512},
abstract = {Endoscopic optical coherence tomography (OCT) offers in vivo live visualization of transmural structures with histological resolution, making it a valuable tool in medical imaging. In gastroenterology, OCT endoscopy is particularly advantageous for assessing rectal wall layers, providing superior axial and lateral resolution compared to conventional rectal endoscopic ultrasound. However, the large diameter and uneven colon surface present challenges for comprehensive imaging. Extending the OCT imaging range addresses this issue by enabling a thorough examination of the entire colon, facilitating the detection of surface polyps, tumors, and their infiltration depth. Once these regions of interest are identified, high-resolution imaging becomes essential for detailed evaluation. To meet these demands, this study integrates two different imaging modes, an extended-range mode, and a high-detail mode, within a rigid rectoscope. The extended-range mode enables visualization of deeper structures, while the high-detail mode enhances image quality for precise, contact-based assessments. The system allows seamless, real-time transitions between the modes using a 3.2MHz-OCT system and a fiber‑optic MEMS switch.},
keywords = {Optical Coherence Tomography, Megahertz OCT, Fourier Domain Mode Locking, Three-dimensional image acquisition, Rectal Imaging, Long-Range Imaging, Non-Invasive Diagnostic Imaging, Tumor Assessment},
year = {2025},
doi = {10.1117/12.3046222},
URL = {https://doi.org/10.1117/12.3046222}
}

@article{Kutscher:25,
author = {Tonio F. Kutscher and Christian Stock and Florian Sommer and Jonas Jurkevicius and Stefan Meyer and Moritz Wiggert and Philipp Lamminger and Sebastian Karpf},
journal = {Opt. Express},
keywords = {Erbium-doped fiber amplifiers; High speed imaging; Laser sources; Optical modulators; Optical parametric oscillators; Swept sources},
number = {5},
pages = {10637--10648},
publisher = {Optica Publishing Group},
title = {Broadband frequency-doubling of a swept-source laser from 1550 nm to 775 nm using a fan-out crystal and application in 2kHz LiDAR ranging},
volume = {33},
month = {Mar},
year = {2025},
url = {https://opg.optica.org/oe/abstract.cfm?URI=oe-33-5-10637},
doi = {10.1364/OE.541976},
abstract = {Swept-source lasers have achieved significant success in sensing, imaging and microscopy. A special type of these lasers is the Fourier-domain mode-locked (FDML) laser, which operates at sweep rates in the megahertz (MHz) range while maintaining high instantaneous monochromaticity. By combining an FDML with an electro optical modulator (EOM) and master oscillator power amplifier (MOPA), a fast wavelength-swept pulsed laser with pulse peak powers in the kilowatt range can be constructed. An extension from the typical near-infrared (NIR) spectral range into the visible (VIS) range could enable a much wider field of applications. A direct approach is not feasible due to the lack of a suitable amplifier medium for MOPAs. A proven alternative is frequency-doubling through phase matching or quasi-phase matching (QPM) from the NIR. However, efficient frequency-doubling of low to mid-power lasers requires longer crystal lengths, limiting the input spectral bandwidth and hence is typically not feasible for broadband swept-source lasers. To overcome this limitation, here we describe a new approach using a periodically poled lithium niobate (PPLN) crystal with a special fan-out QPM structure. Spatial separation of the spectrally distinct pulses using an optical grating is used to obtain ideal QPM conditions for all wavelengths. This new concept allows broadband frequency-doubling and thus the generation of efficient swept laser sources in the NIR and VIS range. In this study we present the frequency-doubling of a 1550 nm FDML-MOPA laser to 775 nm with a pulse peak power of up to 35 W and a spectral span of 10 nm around 775 nm. We show application in ultrafast time-stretch LiDAR with 3D acquisitions of 2000 scans per second. This new laser technology opens up new possibilities for high speed and high bandwidth imaging and spectroscopy.},
}

@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.},
}

@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.},
}

@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}
}

@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{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}}