@article{Schmidt:20,
author = {Mark Schmidt and Tom Pfeiffer and Christin Grill and Robert Huber and Christian Jirauschek},
journal = {OSA Continuum},
keywords = {Doppler effect; Laser modes; Laser sources; Nonlinear effects; Stimulated Raman scattering; Vertical cavity surface emitting lasers},
number = {6},
pages = {1589--1607},
publisher = {Optica Publishing Group},
title = {Self-stabilization mechanism in ultra-stable Fourier domain mode-locked (FDML) lasers},
volume = {3},
month = {Jun},
year = {2020},
url = {https://opg.optica.org/osac/abstract.cfm?URI=osac-3-6-1589},
doi = {10.1364/OSAC.389972},
abstract = {Understanding the dynamics of Fourier domain mode-locked (FDML) lasers is crucial for determining physical coherence limits, and for finding new superior methods for experimental realization. In addition, the rich interplay of linear and nonlinear effects in a laser ring system is of great theoretical interest. Here we investigate the dynamics of a highly dispersion-compensated setup, where over a bandwidth of more than 100\&\#x2009;nm, a highly coherent output with nearly shot-noise-limited intensity fluctuations was experimentally demonstrated. This output is called the sweet-spot. We show by numerical simulation that a finite amount of residual dispersion in the fiber delay cavity of FDML lasers can be compensated by the group delay dispersion in the swept bandpass filter, such that the intensity trace exhibits no dips or high-frequency distortions, which are the main source of noise in the laser. In the same way, a small detuning from the ideal sweep filter frequency can be tolerated. Furthermore, we find that the filter\&\#x2019;s group delay dispersion improves the coherence properties of the laser, and acts as a self-stabilizing element in the cavity. Our theoretical model is validated against experimental data, showing that all relevant physical effects for the sweet-spot operating regime are included.},
}

@article{Kolb:18,
author = {Jan Philip Kolb and Tom Pfeiffer and Matthias Eibl and Hubertus Hakert and Robert Huber},
journal = {Biomed. Opt. Express},
keywords = {Medical optics instrumentation; Lasers, fiber; Medical and biological imaging; Ophthalmic optics and devices ; Optical coherence tomography; Adaptive optics; Image quality; In vivo imaging; Mode locking; Ophthalmic imaging; Three dimensional imaging},
number = {1},
pages = {120--130},
publisher = {Optica Publishing Group},
title = {High-resolution retinal swept source optical coherence tomography with an ultra-wideband Fourier-domain mode-locked laser at MHz A-scan rates},
volume = {9},
month = {Jan},
year = {2018},
url = {https://opg.optica.org/boe/abstract.cfm?URI=boe-9-1-120},
doi = {10.1364/BOE.9.000120},
abstract = {We present a new 1060 nm Fourier domain mode locked laser (FDML laser) with a record 143 nm sweep bandwidth at 2\&\#x2219;\&\#x202F;417 kHz\&\#x202F; $=$ \&\#x202F;834 kHz and 120 nm at 1.67 MHz, respectively. We show that not only the bandwidth alone, but also the shape of the spectrum is critical for the resulting axial resolution, because of the specific wavelength-dependent absorption of the vitreous. The theoretical limit of our setup lies at 5.9 \&\#x00B5;m axial resolution. In vivo MHz-OCT imaging of human retina is performed and the image quality is compared to the previous results acquired with 70 nm sweep range, as well as to existing spectral domain OCT data with 2.1 \&\#x00B5;m axial resolution from literature. We identify benefits of the higher resolution, for example the improved visualization of small blood vessels in the retina besides several others.},
}

@inproceedings{10.1117/12.2287484,
author = {Tom Pfeiffer and Wolfgang Draxinger and Christin Grill and Robert Huber},
title = {{Long-range live 3D-OCT at different spectral zoom levels}},
volume = {10416},
booktitle = {Optical Coherence Imaging Techniques and Imaging in Scattering Media II},
editor = {Maciej Wojtkowski and Stephen A. Boppart and Wang-Yuhl Oh},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {104160L},
abstract = {We demonstrate that the 3.2 MHz a-scan rate and the improved coherence of our new low noise FDML laser enables live 3D-OCT with different spectral zooms and up to 10 cm of imaging range.},
keywords = {Optical coherence tomography, Fourier Domain Mode Locking, FDML, OCT},
year = {2017},
doi = {10.1117/12.2287484},
URL = {https://doi.org/10.1117/12.2287484}
}

@inproceedings{10.1117/12.2286854,
author = {Jan Philip Kolb and Julian Klee and Tom Pfeiffer and Robert Huber},
title = {{1060nm FDML laser with centimeter coherence length and 1.67 MHz sweep rate for full eye length and retinal ultra-widefield OCT}},
volume = {10416},
booktitle = {Optical Coherence Imaging Techniques and Imaging in Scattering Media II},
editor = {Maciej Wojtkowski and Stephen A. Boppart and Wang-Yuhl Oh},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {104160J},
abstract = {We present a new design of a 1060nm Fourier Domain Mode Locked-Laser (FDML-Laser) that combines 1.67 MHz A-scan rate with a centimeter scale coherence length. The extended coherence length is achieved by synchronizing the cavity roundtrip time over the 75 nm sweep with a relative accuracy of 10<sup>-7</sup>. We will show that this requires careful combination of multiple fiber types in the cavity with a gradient heated chirped Fiber Bragg grating.},
keywords = {optical coherence tomograhy, OCT, tunable laser, Fourier domain mode locking, FDML, MHz OCT},
year = {2017},
doi = {10.1117/12.2286854},
URL = {https://doi.org/10.1117/12.2286854}
}

@article{Klein:17,
author = {Thomas Klein and Robert Huber},
journal = {Biomed. Opt. Express},
keywords = {Imaging systems; Optical coherence tomography; Lasers and laser optics; Lasers, tunable; Optical coherence tomography; Full field optical coherence tomography; High speed imaging; Image quality; Imaging systems; Light wavelength; X ray imaging},
number = {2},
pages = {828--859},
publisher = {Optica Publishing Group},
title = {High-speed OCT light sources and systems \[Invited\]},
volume = {8},
month = {Feb},
year = {2017},
url = {https://opg.optica.org/boe/abstract.cfm?URI=boe-8-2-828},
doi = {10.1364/BOE.8.000828},
abstract = {Imaging speed is one of the most important parameters that define the performance of optical coherence tomography (OCT) systems. During the last two decades, OCT speed has increased by over three orders of magnitude. New developments in wavelength-swept lasers have repeatedly been crucial for this development. In this review, we discuss the historical evolution and current state of the art of high-speed OCT systems, with focus on wavelength swept light sources and swept source OCT systems.},
}

@inproceedings{10.1117/12.2254792,
author = {Tom Pfeiffer and Wolfgang Draxinger and Wolfgang Wieser and Thomas Klein and Markus Petermann and Robert Huber},
title = {{Analysis of FDML lasers with meter range coherence}},
volume = {10053},
booktitle = {Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XXI},
editor = {James G. Fujimoto and Joseph A. Izatt and Valery V. Tuchin},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {100531T},
abstract = {FDML lasers provide sweep rates in the MHz range at wide optical bandwidths, making them ideal sources for high
speed OCT. Recently, at lower speed, ultralong-range swept-source OCT has been demonstrated using a tunable
vertical cavity surface emitting laser (VCSEL) and also using a Vernier-tunable laser. These sources provide relatively
high sweep rates and meter range coherence lengths. In order to achieve similar coherence, we developed an extremely
well dispersion compensated Fourier Domain Mode Locked (FDML) laser, running at 3.2 MHz sweep rate and 120 nm
spectral bandwidth. We demonstrate that this laser offers meter range coherence and enables volumetric long range OCT
of moving objects.},
keywords = {Optical coherence tomography, OCT, tunable laser, Fourier domain mode locking, FDML, MHz OCT},
year = {2017},
doi = {10.1117/12.2254792},
URL = {https://doi.org/10.1117/12.2254792}
}

@inproceedings{10.1117/12.2214758,
author = {Jan Philip Kolb and Thomas Klein and Matthias Eibl and Tom Pfeiffer and Wolfgang Wieser and Robert Huber},
title = {{Megahertz FDML laser with up to 143nm sweep range for ultrahigh resolution OCT at 1050nm}},
volume = {9697},
booktitle = {Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XX},
editor = {Joseph A. Izatt and James G. Fujimoto and Valery V. Tuchin},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {969703},
abstract = {We present a new design of a Fourier Domain Mode Locked laser (FDML laser), which provides a new record in sweep
range at ~1μm center wavelength: At the fundamental sweep rate of 2x417 kHz we reach 143nm bandwidth and 120nm
with 4x buffering at 1.67MHz sweep rate. The latter configuration of our system is characterized: The FWHM of the
point spread function (PSF) of a mirror is 5.6μm (in tissue). Human in vivo retinal imaging is performed with the MHz
laser showing more details in vascular structures. Here we could measure an axial resolution of 6.0μm by determining
the FWHM of specular reflex in the image. Additionally, challenges related to such a high sweep bandwidth such as
water absorption are investigated.},
keywords = {Optical coherence tomography, OCT, tunable laser, Fourier domain mode locking, FDML, MHz OCT},
year = {2016},
doi = {10.1117/12.2214758},
URL = {https://doi.org/10.1117/12.2214758}
}

@inproceedings{10.1117/12.2183768,
author = {Jan Philip Kolb and Thomas Klein and Wolfgang Wieser and Wolfgang Draxinger and Robert Huber},
title = {{High definition in vivo retinal volumetric video rate OCT at 0.6 Giga-voxels per second}},
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 = {95410Z},
abstract = {We present full volumetric high speed OCT imaging of the retina with multiple settings varying in volume size and volume rate. The volume size ranges from 255x255 A-scans to 160x40 A-scans with 450 samples per depth scan with volume rates varying between 20.8 V/s for the largest volumes to 195.2 V/s for the smallest. The system is based on a 1060nm Fourier domain mode locked (FDML) laser with 1.6MHz line rate. Scanning along the fast axis is performed with a 2.7 kHz or 4.3 kHz resonant scanner operated in bidirectional scanning mode, while a standard galvo scanner is used for the slow axis. The performance is analyzed with respect to various potential applications, like intraoperative OCT.},
keywords = {Optical coherence tomography, OCT, tunable laser, Fourier domain mode locking, FDML, MHz-OCT},
year = {2015},
doi = {10.1117/12.2183768},
URL = {https://doi.org/10.1117/12.2183768}
}

@inproceedings{10.1117/12.2183431,
author = {Wolfgang Wieser and Thomas Klein and Wolfgang Draxinger and Robert Huber},
title = {{Fully automated 1.5 MHz FDML laser with more than 100mW output power at 1310 nm}},
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 = {954116},
abstract = {While FDML lasers with MHz sweep speeds have been presented five years ago, these devices have required manual control for startup and operation. Here, we present a fully self-starting and continuously regulated FDML laser with a sweep rate of 1.5 MHz. The laser operates over a sweep range of 115 nm centered at 1315 nm, and provides very high average output power of more than 100 mW. We characterize the laser performance, roll-off, coherence length and investigate the wavelength and phase stability of the laser output under changing environmental conditions. The high output power allows optical coherence tomography (OCT) imaging with an OCT sensitivity of 108 dB at 1.5 MHz.},
keywords = {OCT, optical coherence tomography, swept laser, wavelength-swept laser, fiber laser, MHz-OCT, Fourier-domain mode-locking, FDML},
year = {2015},
doi = {10.1117/12.2183431},
URL = {https://doi.org/10.1117/12.2183431}
}

@article{Jirauschek:15,
author = {Christian Jirauschek and Robert Huber},
journal = {Biomed. Opt. Express},
keywords = {Laser theory; Lasers, tunable; Optical coherence tomography; Vertical cavity surface emitting lasers; Distributed Bragg reflectors; Laser light; Laser sources; Quantum well lasers; Swept lasers; Vertical cavity surface emitting lasers},
number = {7},
pages = {2448--2465},
publisher = {Optica Publishing Group},
title = {Wavelength shifting of intra-cavity photons: Adiabatic wavelength tuning in rapidly wavelength-swept lasers},
volume = {6},
month = {Jul},
year = {2015},
url = {https://opg.optica.org/boe/abstract.cfm?URI=boe-6-7-2448},
doi = {10.1364/BOE.6.002448},
abstract = {We analyze the physics behind the newest generation of rapidly wavelength tunable sources for optical coherence tomography (OCT), retaining a single longitudinal cavity mode during operation without repeated build up of lasing. In this context, we theoretically investigate the currently existing concepts of rapidly wavelength-swept lasers based on tuning of the cavity length or refractive index, leading to an altered optical path length inside the resonator. Specifically, we consider vertical-cavity surface-emitting lasers (VCSELs) with microelectromechanical system (MEMS) mirrors as well as Fourier domain mode-locked (FDML) and Vernier-tuned distributed Bragg reflector (VT-DBR) lasers. Based on heuristic arguments and exact analytical solutions of Maxwell's equations for a fundamental laser resonator model, we show that adiabatic wavelength tuning is achieved, i.e., hopping between cavity modes associated with a repeated build up of lasing is avoided, and the photon number is conserved. As a consequence, no fundamental limit exists for the wavelength tuning speed, in principle enabling wide-range wavelength sweeps at arbitrary tuning speeds with narrow instantaneous linewidth.},
}

@article{Huber:15,
author = {Robert Huber},
journal = {Opt. Photon. News},
keywords = {Image processing; Optical coherence tomography; Lasers, tunable; Medical optics and biotechnology; Optical coherence tomography; Image processing; Imaging techniques; Line scan cameras; Medical imaging; Optical coherence tomography; Three dimensional imaging},
number = {6},
pages = {32--39},
publisher = {Optica Publishing Group},
title = {4-D Real-Time Optical Coherence Tomography},
volume = {26},
month = {Jun},
year = {2015},
url = {https://www.optica-opn.org/abstract.cfm?URI=opn-26-6-32},
doi = {10.1364/OPN.26.6.000032},
abstract = {Advances in OCT techniques, combined with the processing power of moderncomputer hardware, are adding a new dimension---time---to a familiar 3-D imaging method.The result could be new applications in research and the biomedicalclinic.},
}

@article{Jirauschek:15,
author = {Christian Jirauschek and Robert Huber},
journal = {Opt. Lett.},
keywords = {Laser theory; Lasers, tunable; Optical coherence tomography; Birefringence; Polarization; Pulses; Cross phase modulation; Mode locking; Optical components; Picosecond pulses; Polarization mode dispersion; Pulse generation},
number = {10},
pages = {2385--2388},
publisher = {Optica Publishing Group},
title = {Modeling and analysis of polarization effects in Fourier domain mode-locked lasers},
volume = {40},
month = {May},
year = {2015},
url = {https://opg.optica.org/ol/abstract.cfm?URI=ol-40-10-2385},
doi = {10.1364/OL.40.002385},
abstract = {We develop a theoretical model for Fourier domain mode-locked (FDML) lasers in a non-polarization-maintaining configuration, which is the most widely used type of FDML source. This theoretical approach is applied to analyze a widely wavelength-swept FDML setup, as used for picosecond pulse generation by temporal compression of the sweeps. We demonstrate that good agreement between simulation and experiment can only be obtained by including polarization effects due to fiber bending birefringence, polarization mode dispersion, and cross-phase modulation into the theoretical model. Notably, the polarization dynamics are shown to have a beneficial effect on the instantaneous linewidth, resulting in improved coherence and thus compressibility of the wavelength-swept FDML output.},
}

@inproceedings{10.1117/12.2214788,
author = {Tom Pfeiffer and Wolfgang Wieser and Thomas Klein and Markus Petermann and Jan-Phillip Kolb and Matthias Eibl and Robert Huber},
title = {{Flexible A-scan rate MHz OCT: computational downscaling by coherent averaging}},
volume = {9697},
booktitle = {Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XX},
editor = {Joseph A. Izatt and James G. Fujimoto and Valery V. Tuchin},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {96970S},
abstract = {In order to realize fast OCT-systems with adjustable line rate, we investigate averaging of image data from an FDML based
MHz-OCT-system. The line rate can be reduced in software and traded in for increased system sensitivity and image
quality. We compare coherent and incoherent averaging to effectively scale down the system speed of a 3.2 MHz FDML
OCT system to around 100 kHz in postprocessing. We demonstrate that coherent averaging is possible with MHz systems
without special interferometer designs or digital phase stabilisation. We show OCT images of a human finger knuckle joint
in vivo with very high quality and deep penetration.},
keywords = {Optical coherence tomography, OCT, Fourier domain mode locking, FDML, MHz OCT, averaging, tunable laser},
year = {2016},
doi = {10.1117/12.2214788},
URL = {https://doi.org/10.1117/12.2214788}
}

@inproceedings{10.1117/12.2077659,
author = {Jan Philip Kolb and Philipp Schwarz and Thomas Klein and Wolfgang Wieser and Robert Huber},
title = {{Dual parametric compounding approach for speckle reduction in OCT}},
volume = {9312},
booktitle = {Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XIX},
editor = {James G. Fujimoto and Joseph A. Izatt and Valery V. Tuchin},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {93123G},
abstract = {OCT as a coherent imaging technique inherently suffers from speckle. We present a new dual parametric compounding approach to reduce speckle. The approach is to acquire several OCT volumes with different numerical apertures (NAs). Then in post processing, a first spatial compounding step is performed by averaging of adjacent B-frames. In a second step data from the different volume is averaged. Retinal imaging data comparing this idea with standard spatial compounding is presented and analyzed and necessary parameters such as the required variation of the NA and number of different NAs are discussed},
keywords = {Optical coherence tomography, OCT, tunable laser, Fourier domain mode lockng, FDML, MHz OCT},
year = {2015},
doi = {10.1117/12.2077659},
URL = {https://doi.org/10.1117/12.2077659}
}

@inproceedings{10.1117/12.2077147,
author = {Jan Philip Kolb and Thomas Klein and Wolfgang Wieser and Wolfgang Draxinger and Robert Huber},
title = {{Full volumetric video rate OCT of the posterior eye with up to 195.2 volumes/s}},
volume = {9312},
booktitle = {Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XIX},
editor = {James G. Fujimoto and Joseph A. Izatt and Valery V. Tuchin},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {931202},
abstract = {Full volumetric high speed OCT imaging of the retina with multiple settings varying in volume size and volume rate is
presented. The volume size ranges from 255x255 A-scans to 160x40 A-scans with 450 samples per depth scan. The
volume rates vary between 20.8 V/s for the largest volumes to 195.2 V/s for the smallest. The system is based on a
1060nm Fourier domain mode locked (FDML) laser with 1.6MHz line rate. Scanning along the fast axis is performed
with a 2.7 kHz or 4.3 kHz resonant scanner operated in bidirectional scanning mode, while a standard galvo scanner is
used for the slow axis. The performance is analyzed with respect to various potential applications, like intraoperative
OCT.},
keywords = {Optical coherence tomography, OCT, tunable laser, Fourier domain mode lockng, FDML, MHz OCT},
year = {2015},
doi = {10.1117/12.2077147},
URL = {https://doi.org/10.1117/12.2077147}
}

@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_Wieser_b,
  Title                    = {{A 4-D OCT Engine with 1 GVoxel/s}},
  Author                   = {Wieser, Wolfgang and Draxinger, Wolfgang and Klein, Thomas and Karpf, Sebastian and Pfeiffer, Tom and Huber, Robert},
  Journal                  = {Optics and Photonics News},
  Year                     = {2014},

  Month                    = dec,
  Number                   = {12},
  Pages                    = {36 },
  Volume                   = {25},
keywords = {AG-Huber_FDML, AG-Huber_OCT},

  Publisher                = {OSA},
  Url                      = { http://www.osa-opn.org/home/articles/volume_25/december_2014/extras/a_4-d_oct_engine_with_1_gvoxel_s/#.VcH21Pl5raw}
}

@Article{HU_2013_Eigenwillig_b,
  Title                    = {{Picosecond pulses from wavelength-swept continuous-wave Fourier domain mode-locked lasers}},
  Author                   = {Eigenwillig, Christoph M and Wieser, Wolfgang and Todor, Sebastian and Biedermann, Benjamin R and Klein, Thomas and Jirauschek, Christian and Huber, Robert},
  Journal                  = {Nature communications},
  Year                     = {2013},
  Month                    = jan,
  Pages                    = {1848--1855},
  Volume                   = {4},
  Doi                      = {10.1038/ncomms2870},
  ISSN                     = {2041-1723},
keywords = {AG-Huber_FDML, AG-Huber_OCT},
  Url                      = {http://www.nature.com/ncomms/journal/v4/n5/abs/ncomms2870.html}
}

@INPROCEEDINGS{6801076,
  author={Eigenwillig, Christoph M. and Todor, Sebastian and Wieser, Wolfgang and Biedermann, Benjamin R. and Klein, Thomas and Jirauschek, Christian and Huber, Robert},
  booktitle={2013 Conference on Lasers & Electro-Optics Europe & International Quantum Electronics Conference CLEO EUROPE/IQEC}, 
  title={Picosecond pulses from a Fourier domain mode locked (FDML) laser}, 
  year={2013},
  volume={},
  number={},
  pages={1-1},
  doi={10.1109/CLEOE-IQEC.2013.6801076}}

@article{10.1117/1.JBO.18.2.026008,
author = {Teresa Torzicky and Sebastian Marschall and Michael Pircher and Bernhard Baumann and Marco Bonesi and Stefan Zotter and Erich G{\"o}tzinger and Wolfgang Trasischker and Thomas Klein and Wolfgang Wieser and Benjamin R. Biedermann and Robert A. Huber and Peter E. Andersen and Christoph K. Hitzenberger},
title = {{Retinal polarization-sensitive optical coherence tomography at 1060 nm with 350 kHz A-scan rate using an Fourier domain mode locked laser}},
volume = {18},
journal = {Journal of Biomedical Optics},
number = {2},
publisher = {SPIE},
pages = {026008},
abstract = {We present a novel, high-speed, polarization-sensitive, optical coherence tomography set-up for retinal imaging operating at a central wavelength of 1060 nm which was tested for in vivo imaging in healthy human volunteers. We use the system in combination with a Fourier domain mode locked laser with active spectral shaping which enables the use of forward and backward sweep in order to double the imaging speed without a buffering stage. With this approach and with a custom designed data acquisition system, we show polarization-sensitive imaging with an A-scan rate of 350 kHz. The acquired three-dimensional data sets of healthy human volunteers show different polarization characteristics in the eye, such as depolarization in the retinal pigment epithelium and birefringence in retinal nerve fiber layer and sclera. The increased speed allows imaging of large volumes with reduced motion artifacts. Moreover, averaging several two-dimensional frames allows the generation of high-definition B-scans without the use of an eye-tracking system. The increased penetration depth of the system, which is caused by the longer probing beam wavelength, is beneficial for imaging choroidal and scleral structures and allows automated segmentation of these layers based on their polarization characteristics.},
keywords = {Optical coherence tomography, Polarization, Birefringence, Imaging systems, Data acquisition, Image segmentation, Modulation, Mode locking, 3D acquisition, Retinal scanning},
year = {2013},
doi = {10.1117/1.JBO.18.2.026008},
URL = {https://doi.org/10.1117/1.JBO.18.2.026008}
}

@article{Bonesi:12,
author = {Marco Bonesi and Harald Sattmann and Teresa Torzicky and Stefan Zotter and Bernhard Baumann and Michael Pircher and Erich G\"{o}tzinger and Christoph Eigenwillig and Wolfgang Wieser and Robert Huber and Christoph K. Hitzenberger},
journal = {Biomed. Opt. Express},
keywords = {Optical coherence tomography; Optical diagnostics for medicine; Polarization-selective devices; High speed imaging; Image quality; Laser modes; Mode locking; Single mode fibers; Three dimensional imaging},
number = {11},
pages = {2987--3000},
publisher = {Optica Publishing Group},
title = {High-speed polarization sensitive optical coherence tomography scan engine based on Fourier domain mode locked laser},
volume = {3},
month = {Nov},
year = {2012},
url = {https://opg.optica.org/boe/abstract.cfm?URI=boe-3-11-2987},
doi = {10.1364/BOE.3.002987},
abstract = {We report on a new swept source polarization sensitive optical coherence tomography scan engine that is based on polarization maintaining (PM) fiber technology. The light source is a Fourier domain mode locked laser with a PM cavity that operates in the 1300 nm wavelength regime. It is equipped with a PM buffer stage that doubles the fundamental sweep frequency of 54.5 kHz. The fiberization allows coupling of the scan engine to different delivery probes. In a first demonstration, we use the system for imaging human skin at an A-scan rate of 109 kHz. The system illuminates the sample with circularly polarized light and measures reflectivity, retardation, optic axis orientation, and Stokes vectors simultaneously. Furthermore, depolarization can be quantified by calculating the degree of polarization uniformity (DOPU). The high scanning speed of the system enables dense sampling in both, the x- and y-direction, which provides the opportunity to use 3D evaluation windows for DOPU calculation. This improves the spatial resolution of DOPU images considerably.},
}

@article{Blatter:12,
author = {Cedric Blatter and Branislav Grajciar and Pu Zou and Wolfgang Wieser and Aart-Jan Verhoef and Robert Huber and Rainer A. Leitgeb},
journal = {Opt. Lett.},
keywords = {Optical coherence tomography; Optical coherence tomography; Photoacoustic imaging; Interferometric imaging ; Photoacoustics ; In vivo imaging; Interferometry; Linewidth; Medical imaging; Optical coherence tomography; Swept sources},
number = {21},
pages = {4368--4370},
publisher = {Optica Publishing Group},
title = {Intrasweep phase-sensitive optical coherence tomography for noncontact optical photoacoustic imaging},
volume = {37},
month = {Nov},
year = {2012},
url = {https://opg.optica.org/ol/abstract.cfm?URI=ol-37-21-4368},
doi = {10.1364/OL.37.004368},
abstract = {We introduce a method to extract the photoacoustic (PA) signal from the phase time evolution of an optical coherence tomography (OCT) swept source spectral sweep. This all-optical detection is achieved in a noncontact fashion directly on the sample surface by using its specular reflection. High-speed measurement and referencing allow for close to shot noise limited phase-sensitive detection. It offers a simple way to perform OCT and PA imaging by sharing the same system components.},
}

@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{10.1117/12.922313,
author = {Sebastian Marschall and Teresa Torzicky and Thomas Klein and Wolfgang Wieser and Michael Pircher and Erich G{\"o}tzinger and Stefan Zotter and Marco Bonesi and Benjamin Biedermann and Christian Pedersen and Robert Huber and Christoph Hitzenberger and Peter Andersen},
title = {{High-speed polarization-sensitive OCT at 1060 nm using a Fourier domain mode-locked swept source}},
volume = {8427},
booktitle = {Biophotonics: Photonic Solutions for Better Health Care III},
editor = {J{\"u}rgen Popp and Wolfgang Drexler and Valery V. Tuchin and Dennis L. Matthews},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {84271D},
abstract = {Optical coherence tomography (OCT) in the 1060nm range is interesting for in vivo imaging of the human
posterior eye segment (retina, choroid, sclera), as it permits a long penetration depth. Complementary to
structural images, polarization-sensitive OCT (PS-OCT) images visualize birefringent, polarization-maintaining
or depolarizing areas within the sample. This information can be used to distinguish retinal layers and structures
with different polarization properties. High imaging speed is crucial for imaging ocular structures in vivo in order
to minimize motion artifacts while acquiring sufficiently large datasets. Here, we demonstrate PS-OCT imaging
at 350 kHz A-scan rate using a two-channel PS-OCT system in conjunction with a Fourier domain mode-locked
laser. The light source spectrum spans up to 100nm around the water absorption minimum at 1060 nm. By
modulating the laser pump current, we can optimize the spectrum and achieve a depth resolution of 9 μm in air
(6.5 μm in tissue). We acquired retinal images in vivo with high resolution and deep penetration into choroid and
sclera, and features like the depolarizing RPE or an increasing phase retardation at the chorio-scleral interface
are clearly visualized.},
keywords = {optical coherence tomography, polarization-sensitive OCT, swept source, Fourier domain mode-locking, 1060 nm},
year = {2012},
doi = {10.1117/12.922313},
URL = {https://doi.org/10.1117/12.922313}
}

@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.},
}