@article{Todor:12,
author = {Sebastian Todor and Benjamin Biedermann and Robert Huber and Christian Jirauschek},
journal = {J. Opt. Soc. Am. B},
keywords = {Laser theory; Lasers, tunable; Optical coherence tomography; Mode locking; Numerical simulation; Optical amplifiers; Power spectra; Swept lasers; Tunable lasers},
number = {4},
pages = {656--664},
publisher = {Optica Publishing Group},
title = {Balance of physical effects causing stationary operation of Fourier domain mode-locked lasers},
volume = {29},
month = {Apr},
year = {2012},
url = {https://opg.optica.org/josab/abstract.cfm?URI=josab-29-4-656},
doi = {10.1364/JOSAB.29.000656},
abstract = {We present a detailed analysis of the optical field dynamics in a Fourier domain mode-locked (FDML) laser. We employ a numerical simulation based on the FDML evolution equation, describing the propagation of the optical light field. The temporal evolution of the instantaneous power spectrum at different points in the laser cavity is investigated. The results are carefully validated against experimental data, yielding good agreement. Deeper insight is gained into the role of the physical effects governing FDML dynamics, such as gain recovery and linewidth enhancement in the semiconductor optical amplifier, dispersion and self-phase modulation in the optical fiber, and the sweep filter action.},
}

@Article{HU_2012_Wieser_a,
  Title                    = {{Chromatic polarization effects of swept waveforms in FDML lasers and fiber spools}},
  Author                   = {Wieser, Wolfgang and Palte, Gesa and Eigenwillig, Christoph M and Biedermann, Benjamin R and Pfeiffer, Tom and Huber, Robert},
  Journal                  = {Optics express},
  Year                     = {2012},

  Month                    = apr,
  Number                   = {9},
  Pages                    = {9819--32},
  Volume                   = {20},

  Doi                      = {10.1364/OE.20.009819},
  ISSN                     = {1094-4087},
keywords = {AG-Huber_FDML, AG-Huber_OCT},
  Url                      = {http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-20-9-9819\&id=231991}
}

@inproceedings{10.1117/12.906148,
author = {Sebastian Marschall and Thomas Klein and Wolfgang Wieser and Teresa Torzicky and Michael Pircher and Benjamin R. Biedermann and Christian Pedersen and Christoph K. Hitzenberger and Robert Huber and Peter E. Andersen},
title = {{Broadband Fourier domain mode-locked laser for optical coherence tomography at 1060 nm}},
volume = {8213},
booktitle = {Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XVI},
editor = {Joseph A. Izatt and James G. Fujimoto and Valery V. Tuchin},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {82130R},
abstract = {Optical coherence tomography (OCT) in the 1060nm range is interesting for in vivo imaging of the human
posterior eye segment (retina, choroid, sclera) due to low absorption in water and deep penetration into the
tissue. Rapidly tunable light sources, such as Fourier domain mode-locked (FDML) lasers, enable acquisition
of densely sampled three-dimensional datasets covering a wide field of view. However, semiconductor optical
amplifiers (SOAs)-the typical laser gain media for swept sources-for the 1060nm band could until recently
only provide relatively low output power and bandwidth. We have implemented an FDML laser using a new SOA
featuring broad gain bandwidth and high output power. The output spectrum coincides with the wavelength
range of minimal water absorption, making the light source ideal for OCT imaging of the posterior eye segment.
With a moderate SOA current (270 mA) we achieve up to 100nm total sweep range and 12 μm depth resolution
in air. By modulating the current, we can optimize the output spectrum and thereby improve the resolution to
9 μm in air (~6.5 μm in tissue). The average output power is higher than 20mW. Both sweep directions show
similar performance; hence, both can be used for OCT imaging. This enables an A-scan rate of 350 kHz without
buffering the light source output.},
keywords = {optical coherence tomography, tunable laser, swept source, Fourier domain mode-locking, broadband semiconductor optical amplifier},
year = {2012},
doi = {10.1117/12.906148},
URL = {https://doi.org/10.1117/12.906148}
}

@inproceedings{10.1117/12.908798,
author = {Thomas Klein and Wolfgang Wieser and Raphael Andr{\'e} and Tom Pfeiffer and Christoph M. Eigenwillig and Robert Huber},
title = {{Multi-MHz FDML OCT: snapshot retinal imaging at 6.7 million axial-scans per second}},
volume = {8213},
booktitle = {Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XVI},
editor = {Joseph A. Izatt and James G. Fujimoto and Valery V. Tuchin},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {82131E},
abstract = {We demonstrate the acquisition of densely sampled wide-field 3D OCT datasets of the human retina in 0.3s. This
performance is achieved with a multi-MHz Fourier domain mode-locked (FDML) laser source operating at 1050nm. A two-beam
setup doubles the 3.35MHz laser sweep rate to 6.7MHz, which is 16x faster than results achieved with any non-FDML
source used for retinal OCT. We discuss two main benefits of these high line rates: First, large datasets over an ultra-wide
field of view can be acquired with a low probability of distortions. Second, even if eye movements occur, now the scan rate
is high enough to directly correct even the fastest saccades without loss of information.},
keywords = {Optical coherence tomography, OCT, MHz OCT, Fourier-domain mode-locking, FDML, retinal imaging},
year = {2012},
doi = {10.1117/12.908798},
URL = {https://doi.org/10.1117/12.908798}
}

@inproceedings{10.1117/12.909830,
author = {Cedric Blatter and Branislav Grajciar and Robert Huber and Rainer A. Leitgeb},
title = {{Deep skin structural and microcirculation imaging with extended-focus OCT}},
volume = {8207},
booktitle = {Photonic Therapeutics and Diagnostics VIII},
editor = {Anita Mahadevan-Jansen and E. Duco Jansen and Andreas Mandelis and Kenton W. Gregory M.D. and Guillermo J. Tearney M.D. and Laura Marcu and Nikiforos Kollias and Bernard Choi and Haishan Zeng and Melissa J. Suter and Stephen Lam and Matthew Brenner and Hyun Wook Kang and Bodo E. Knudsen M.D. and Henry Hirschberg M.D. and Steen Madsen and Brian Jet-Fei Wong M.D. and Justus F. Ilgner M.D. and Krzysztof Izdebski},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {82070B},
abstract = {We present an extended focus OCT system for dermatologic applications that maintains high lateral resolution over a
large depth range by using Bessel beam illumination. More, Bessel beams exhibit a self-reconstruction property that is
particularly useful to avoid shadowing from surface structures such as hairs. High lateral resolution and high-speed
measurement, thanks to a rapidly tuning swept source, allows not only for imaging of small skin structures in depth but
also for comprehensive visualization of the small capillary network within the human skin in-vivo. We use this
information for studying temporal vaso-responses to hypothermia. In contrast to other perfusion imaging methods such
as laser Doppler imaging (LDI), OCT gives specific access to vascular responses in different vascular beds in depth.},
keywords = {Optical Coherence Tomography, FDML Swept Source, Extended focus, Bessel beam, Self-reconstruction property, Microcirculation imaging, Vasomechanics},
year = {2012},
doi = {10.1117/12.909830},
URL = {https://doi.org/10.1117/12.909830}
}

@inproceedings{10.1117/12.908148,
author = {Desmond C. Adler and Wolfgang Wieser and Francois Trepanier and Joseph M. Schmitt and Robert A. Huber},
title = {{Coherence length extension of Fourier domain mode locked lasers}},
volume = {8213},
booktitle = {Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XVI},
editor = {Joseph A. Izatt and James G. Fujimoto and Valery V. Tuchin},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {82130O},
abstract = {Fourier domain mode locked (FDML) lasers provide high sweep rates, broad tuning ranges, and high output powers for
optical coherence tomography (OCT) systems. However, presently-known FDML lasers at 1300 nm have relatively
short coherence lengths, limiting the size of samples that can be imaged. Furthermore, FDML lasers produce only one
useable sweep direction. We report FDML coherence length extension by incorporating advanced dispersion
compensation modules (DCMs). DCMs eliminate group velocity dispersion in the cavity, doubling coherence lengths
and ensuring uniform axial resolution over the imaging range. Additionally, forward and backward sweeps are nearly
identical, removing the need for external buffering stages.},
keywords = {Fourier domain mode locked lasers, FDML, swept source, optical coherence tomography, dispersion compensation},
year = {2012},
doi = {10.1117/12.908148},
URL = {https://doi.org/10.1117/12.908148}
}

@Article{HU_2012_Klein_a,
  Title                    = {{OPTICAL COHERENCE TOMOGRAPHY/HIGH-SPEED BIOMEDICAL IMAGING: No speed limit: The multi-megahertz approach to optical coherence tomography}},
  Author                   = {Klein, Thomas and Wieser, Wolfgang and Huber, Robert},
  Journal                  = {BioOptics World},
  Year                     = {2012},
  Number                   = {1},
  Pages                    = {28--32},
  Volume                   = {5},
keywords = {AG-Huber_FDML, AG-Huber_OCT},
  Doi                      = {http://www.bioopticsworld.com/articles/print/volume-5/issue-1/features/the-multi-megahertz-approach-to-optical-coherence-tomography.html},
  Url                      = {http://www.bioopticsworld.com/articles/print/volume-5/issue-1/features/the-multi-megahertz-approach-to-optical-coherence-tomography.html}
}

@article{https://doi.org/10.1002/jbio.201000104,
author = {Eigenwillig, Christoph M. and Klein, Thomas and Wieser, Wolfgang and Biedermann, Benjamin R. and Huber, Robert},
title = {Wavelength swept amplified spontaneous emission source for high speed retinal optical coherence tomography at 1060 nm},
journal = {Journal of Biophotonics},
volume = {4},
number = {7-8},
pages = {552-558},
keywords = {optical coherence tomography, tunable lasers, optical frequency domain imaging, ophthalmology},
doi = {https://doi.org/10.1002/jbio.201000104},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/jbio.201000104},
eprint = {https://onlinelibrary.wiley.com/doi/pdf/10.1002/jbio.201000104},
abstract = {Abstract The wavelength swept amplified spontaneous emission (ASE) source presented in this paper is an alternative approach to realize a light source for high speed swept source optical coherence tomography (OCT). ASE alternately passes a cascade of different optical gain elements and tunable optical bandpass filters. In this work we show for the first time a wavelength swept ASE source in the 1060 nm wavelength range, enabling high speed retinal OCT imaging. We demonstrate ultra-rapid retinal OCT at a line rate of 170 kHz, a record sweep rate at 1060 nm of 340 kHz with 70 nm full sweep width, enabling an axial resolution of 11 μm. Two different implementations of the source are characterized and compared to each other. The last gain element is either a semiconductor optical amplifier or an Ytterbium-doped fibre amplifier enabling high average output power of >40 mW. Various biophotonic imaging examples provide a wide range of quality benchmarks achievable with such sources. (© 2011 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim)},
year = {2011}
}

@article{Adler:11,
author = {Desmond C. Adler and Wolfgang Wieser and Francois Trepanier and Joseph M. Schmitt and Robert A. Huber},
journal = {Opt. Express},
keywords = {Optical coherence tomography; Lasers, tunable; Medical optics and biotechnology; Dispersion compensation devices ; Fiber Bragg gratings ; Laser modes; Laser sources; Mode locking; Optical delay lines; Swept lasers; Tunable lasers},
number = {21},
pages = {20930--20939},
publisher = {Optica Publishing Group},
title = {Extended coherence length Fourier domain mode locked lasers at 1310 nm},
volume = {19},
month = {Oct},
year = {2011},
url = {https://opg.optica.org/oe/abstract.cfm?URI=oe-19-21-20930},
doi = {10.1364/OE.19.020930},
abstract = {Fourier domain mode locked (FDML) lasers are excellent tunable laser sources for frequency domain optical coherence tomography (FD-OCT) systems due to their combination of high sweep rates, large tuning ranges, and high output powers. However, conventional FDML lasers provide coherence lengths of only 4--10 mm, limiting their use in demanding applications such as intravascular OCT where coherence lengths of \>20 mm are required for optimal imaging of large blood vessels. Furthermore, like most swept lasers, conventional FDML lasers produce only one useable sweep direction per tunable filter drive cycle, halving the effective sweep rate of the laser compared to the filter drive frequency. Here, we demonstrate a new class of FDML laser incorporating broadband dispersion compensation near 1310 nm. Elimination of chromatic dispersion in the FDML cavity results in the generation of forward (short to long wavelength) and backward (long to short wavelength) sweeps with substantially identical properties and coherence lengths of \>21 mm. This advance enables long-range, high-speed FD-OCT imaging without the need for optical buffering stages, significantly reducing laser cost and complexity.},
}

@inproceedings{Klein:11,
author = {Thomas Klein and Wolfgang Wieser and Benjamin R. Biedermann and Christoph M. Eigenwillig and Robert Huber},
booktitle = {CLEO:2011 - Laser Applications to Photonic Applications},
journal = {CLEO:2011 - Laser Applications to Photonic Applications},
keywords = {Optical coherence tomography; Lasers, tunable; Image quality; Imaging techniques; Laser modes; Medical imaging; Mode locking; Optical coherence tomography},
pages = {CWB1},
publisher = {Optica Publishing Group},
title = {FDML laser for megahertz retinal OCT imaging},
year = {2011},
url = {https://opg.optica.org/abstract.cfm?URI=CLEO_SI-2011-CWB1},
doi = {10.1364/CLEO_SI.2011.CWB1},
abstract = {A novel Fourier-domain mode locked (FDML) laser design is presented, yielding the highest wavelength sweep speed reported so far around 1050nm. This enables retinal imaging over a ~70{\textdegree} ultra-wide field of view.},
}

@inproceedings{10.1117/12.889669,
author = {Cedric Blatter and Branislav Grajciar and Christoph M. Eigenwillig and Wolfgang Wieser and Benjamin R. Biedermann and Robert Huber and Rainer A. Leitgeb},
title = {{High-speed functional OCT with self-reconstructive Bessel illumination at 1300 nm}},
volume = {8091},
booktitle = {Optical Coherence Tomography and Coherence Techniques V},
editor = {Rainer A. Leitgeb and Brett E. Bouma},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {809104},
abstract = {We present a Bessel beam illumination FDOCT setup with FDML buffered swept source at 1300nm. An extended focus
is achieved due to the Bessel beam that preserves its lateral extend over a large depth range. Decoupling the illumination
from the Gaussian detection improves the sensitivity as compared to double passing the ring filter and enables dark field
imaging. Dark field imaging is useful to avoid strong reflexes from the sample's surface that adversely affect the
sensitivity due to the limited dynamic range of high-speed 8bit acquisition cards. Furthermore, Bessel beams exhibit a
self-reconstruction property that allows imaging even behind obstacles such as hairs on skin.
Densely sampled volumes of skin in-vivo with high lateral resolution are acquired at up to 440kHz A-Scan rate. In
addition the possibility of contrasting capillaries with high sensitivity is shown, using inter-B-scan speckle variance
analysis. High-speed imaging is of crucial importance for imaging small details since sample motion artifacts are
reduced and high sampling can be maintained while increasing the B-Scan rate.},
keywords = {Extended focus, Bessel beam, Self-reconstructive illumination, Dark field imaging, Dermatology, Microcirculation imaging, FDML, Swept Source},
year = {2011},
doi = {10.1117/12.889669},
URL = {https://doi.org/10.1117/12.889669}
}

@article{Todor:11,
author = {Sebastian Todor and Benjamin Biedermann and Wolfgang Wieser and Robert Huber and Christian Jirauschek},
journal = {Opt. Express},
keywords = {Laser theory; Lasers, tunable; Optical coherence tomography; Linewidth; Laser sources; Mode locking; Power spectra; Semiconductor lasers; Swept lasers; Tunable lasers},
number = {9},
pages = {8802--8807},
publisher = {Optica Publishing Group},
title = {Instantaneous lineshape analysis of Fourier domain mode-locked lasers},
volume = {19},
month = {Apr},
year = {2011},
url = {https://opg.optica.org/oe/abstract.cfm?URI=oe-19-9-8802},
doi = {10.1364/OE.19.008802},
abstract = {We present a theoretical and experimental analysis of the instantaneous lineshape of Fourier domain mode-locked (FDML) lasers, yielding good agreement. The simulations are performed employing a recently introduced model for FDML operation. Linewidths around 10 GHz are found, which is significantly below the sweep filter bandwidth. The effect of detuning between the sweep filter drive frequency and cavity roundtrip time is studied revealing features that cannot be resolved in the experiment, and shifting of the instantaneous power spectrum against the sweep filter center frequency is analyzed. We show that, in contrast to most other semiconductor based lasers, the instantaneous linewidth is governed neither by external noise sources nor by amplified spontaneous emission, but it is directly determined by the complex FDML dynamics.},
}

@article{Klein:11,
author = {Thomas Klein and Wolfgang Wieser and Christoph M. Eigenwillig and Benjamin R. Biedermann and Robert Huber},
journal = {Opt. Express},
keywords = {Optical coherence tomography; Lasers, tunable; Imaging systems; Ophthalmology; Optical coherence tomography; Retina scanning ; Fiber lasers; Image processing; Image quality; Mode locking; Ophthalmic imaging; Three dimensional imaging},
number = {4},
pages = {3044--3062},
publisher = {Optica Publishing Group},
title = {Megahertz OCT for ultrawide-field retinal imaging with a 1050nm Fourier domain mode-locked laser},
volume = {19},
month = {Feb},
year = {2011},
url = {https://opg.optica.org/oe/abstract.cfm?URI=oe-19-4-3044},
doi = {10.1364/OE.19.003044},
abstract = {We demonstrate ultrahigh speed swept source retinal OCT imaging using a Fourier domain mode locked (FDML) laser. The laser uses a combination of a semiconductor optical amplifier and an ytterbium doped fiber amplifier to provide more than 50mW output power. The 1050nm FDML laser uses standard telecom fiber for the km long delay line instead of two orders of magnitude more expensive real single mode fiber. We investigate the influence of this ``oligo-mode'' fiber on the FDML laser performance. Two design configurations with 684,400 and 1,368,700 axial scans per second are investigated, 25x and 50x faster than current commercial instruments and more than 4x faster than previous single spot ophthalmic results. These high speeds enable the acquisition of densely sampled ultrawide-field data sets of the retina within a few seconds. Ultrawide-field data consisting of 1900 x 1900 A-scans with ~70{\textdegree} degrees angle of view are acquired within only 3 and 6 seconds using the different setups. Such OCT data sets, more than double as large as previously reported, are collapsed to a 4 megapixel high definition fundus image. We achieve good penetration into the choroid by hardware spectral shaping of the laser output. The axial resolution in tissue is 12{\textmu}m (684kHz) and 19{\textmu}m (1.37MHz). A series of new data processing and imaging extraction protocols, enabled by the ultrawide-field isotropic data sets, are presented. Dense isotropic sampling enables both, cross-sectional images along arbitrary coordinates and depth-resolved en-face fundus images. Additionally, we investigate how isotropic averaging compares to the averaging of cross-sections along the slow axis.},
}

@article{Wieser:10,
author = {Wolfgang Wieser and Benjamin R. Biedermann and Thomas Klein and Christoph M. Eigenwillig and Robert Huber},
journal = {Opt. Photon. News},
keywords = {General; Analog to digital converters; Crystallography; Image quality; Optical coherence tomography; Real time imaging; Three dimensional imaging},
number = {12},
pages = {28--28},
publisher = {Optica Publishing Group},
title = {High-Quality 3-D Imaging withMultimegahertz OCT},
volume = {21},
month = {Dec},
year = {2010},
url = {https://www.optica-opn.org/abstract.cfm?URI=opn-21-12-28},
doi = {10.1364/OPN.21.12.000028},
abstract = {We have developed interferometric systems to measure nanosize structures and freeze their motion in time. Researchers have also suggested a method to extract both phase and amplitude information for crystallography.},
}

@article{Biedermann:10,
author = {Benjamin R. Biedermann and Wolfgang Wieser and Christoph M. Eigenwillig and Thomas Klein and Robert Huber},
journal = {Opt. Lett.},
keywords = {Optical coherence tomography; Lasers, tunable; Electrooptical modulators; Fourier transforms; Laser light; Laser sources; Optical coherence tomography; Swept lasers},
number = {22},
pages = {3733--3735},
publisher = {Optica Publishing Group},
title = {Direct measurement of the instantaneous linewidth of rapidly wavelength-swept lasers},
volume = {35},
month = {Nov},
year = {2010},
url = {https://opg.optica.org/ol/abstract.cfm?URI=ol-35-22-3733},
doi = {10.1364/OL.35.003733},
abstract = {The instantaneous linewidth of rapidly wavelength-swept laser sources as used for optical coherence tomography (OCT) is of crucial interest for a deeper understanding of physical effects involved in their operation. Swept lasers for OCT, typically sweeping over ~15 THz in ~10$\mu$s, have linewidths of several gigahertz. The high optical-frequency sweep speed makes it impossible to measure the instantaneous spectrum with standard methods. Hence, up to now, experimental access to the instantaneous linewidth was rather indirect by the inverse Fourier transform of the coherence decay. In this Letter, we present a method by fast synchronous time gating and extraction of a ``snapshot'' of the instantaneous spectrum with an electro-optic modulator, which can subsequently be measured with an optical spectrum analyzer. This new method is analyzed in detail, and systematic artifacts, such as sideband generation due to the modulation and residual wavelength uncertainty due to the sweeping operation, are quantified. The method is checked for consistency with results from the common, more indirect measurement via coherence properties.},
}

@article{Marschall:10,
author = {Sebastian Marschall and Thomas Klein and Wolfgang Wieser and Benjamin R. Biedermann and Kevin Hsu and Kim P. Hansen and Bernd Sumpf and Karl-Heinz Hasler and G\"{o}tz Erbert and Ole B. Jensen and Christian Pedersen and Robert Huber and Peter E. Andersen},
journal = {Opt. Express},
keywords = {Optical coherence tomography; Lasers, tunable; Semiconductor lasers; Semiconductor optical amplifiers; Dispersion; High speed imaging; Laser light; Optical delay lines; Optical fibers; Optical standards; Swept sources},
number = {15},
pages = {15820--15831},
publisher = {Optica Publishing Group},
title = {Fourier domain mode-locked swept source at 1050 nm based on a tapered amplifier},
volume = {18},
month = {Jul},
year = {2010},
url = {https://opg.optica.org/oe/abstract.cfm?URI=oe-18-15-15820},
doi = {10.1364/OE.18.015820},
abstract = {While swept source optical coherence tomography (OCT) in the 1050 nm range is promising for retinal imaging, there are certain challenges. Conventional semiconductor gain media have limited output power, and the performance of high-speed Fourier domain mode-locked (FDML) lasers suffers from chromatic dispersion in standard optical fiber. We developed a novel light source with a tapered amplifier as gain medium, and investigated the FDML performance comparing two fiber delay lines with different dispersion properties. We introduced an additional gain element into the resonator, and thereby achieved stable FDML operation, exploiting the full bandwidth of the tapered amplifier despite high dispersion. The light source operates at a repetition rate of 116 kHz with an effective average output power in excess of 30 mW. With a total sweep range of 70 nm, we achieved an axial resolution of 15 {\textmu}m in air (~11 {\textmu}m in tissue) in OCT measurements. As our work shows, tapered amplifiers are suitable gain media for swept sources at 1050 nm with increased output power, while high gain counteracts dispersion effects in an FDML laser.},
}

@article{Wieser:10,
author = {Wolfgang Wieser and Benjamin R. Biedermann and Thomas Klein and Christoph M. Eigenwillig and Robert Huber},
journal = {Opt. Express},
keywords = {Optical coherence tomography; Three-dimensional image acquisition; Lasers, tunable; Optical coherence tomography; Biological imaging; High speed imaging; Image processing algorithms; Image quality; Point spread function; Three dimensional imaging},
number = {14},
pages = {14685--14704},
publisher = {Optica Publishing Group},
title = {Multi-Megahertz OCT: High quality 3D imaging at 20 million A-scans and 4.5 GVoxels per second},
volume = {18},
month = {Jul},
year = {2010},
url = {https://opg.optica.org/oe/abstract.cfm?URI=oe-18-14-14685},
doi = {10.1364/OE.18.014685},
abstract = {We present ultra high speed optical coherence tomography (OCT) with multi-megahertz line rates and investigate the achievable image quality. The presented system is a swept source OCT setup using a Fourier domain mode locked (FDML) laser. Three different FDML-based swept laser sources with sweep rates of 1, 2.6 and 5.2MHz are compared. Imaging with 4 spots in parallel quadruples the effective speed, enabling depth scan rates as high as 20.8 million lines per second. Each setup provides at least 98dB sensitivity and ~10{\textmu}m resolution in tissue. High quality 2D and 3D imaging of biological samples is demonstrated at full scan speed. A discussion about how to best specify OCT imaging speed is included. The connection between voxel rate, line rate, frame rate and hardware performance of the OCT setup such as sample rate, analog bandwidth, coherence length, acquisition dead-time and scanner duty cycle is provided. Finally, suitable averaging protocols to further increase image quality are discussed.},
}

@inproceedings{10.1117/12.854238,
author = {Sebastian Marschall and Thomas Klein and Wolfgang Wieser and Benjamin Biedermann and Kevin Hsu and Bernd Sumpf and Karl-Heinz Hasler and G{\"o}tz Erbert and Ole B. Jensen and Christian Pedersen and Robert Huber and Peter E. Andersen},
title = {{High-power FDML laser for swept source-OCT at 1060 nm}},
volume = {7715},
booktitle = {Biophotonics: Photonic Solutions for Better Health Care II},
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 = {77150B},
abstract = {We present a novel frequency-swept light source working at 1060nm that utilizes a tapered amplifier as gain
medium. These devices feature significantly higher saturation power than conventional semiconductor optical
amplifiers and can thus improve the limited output power of swept sources in this wavelength range. We
demonstrate that a tapered amplifier can be integrated into a 
fiber-based swept source and allows for high-speed
FDML operation. The developed light source operates at a sweep rate of 116kHz with an effective average
output power in excess of 30mW. With a total sweep range of 70 nm an axial resolution of 15 μm in air (~11μm
in tissue) for OCT applications can be achieved.},
keywords = {optical coherence tomography, swept source, tunable laser, tapered amplifier, fourier domain mode-locking},
year = {2010},
doi = {10.1117/12.854238},
URL = {https://doi.org/10.1117/12.854238}
}

@inproceedings{Todor:10,
author = {Sebastian Todor and Christian Jirauschek and Benjamin Biedermann and Robert Huber},
booktitle = {Conference on Lasers and Electro-Optics 2010},
journal = {Conference on Lasers and Electro-Optics 2010},
keywords = {Lasers and laser optics; Laser theory; Lasers, tunable; Laser light; Laser operation; Mode locking; Optical amplifiers; Self phase modulation; Tunable lasers},
pages = {CMW7},
publisher = {Optica Publishing Group},
title = {Linewidth Optimization of Fourier Domain Mode-Locked Lasers},
year = {2010},
url = {https://opg.optica.org/abstract.cfm?URI=CLEO-2010-CMW7},
doi = {10.1364/CLEO.2010.CMW7},
abstract = {We theoretically and experimentally investigate the instantaneous linewidth of Fourier domain mode-locked lasers, yielding good agreement. Based on simulations, strategies are discussed to drastically reduce the laser linewidth.},
}

@inproceedings{10.1117/12.842011,
author = {Sebastian Marschall and Thomas Klein and Wolfgang Wieser and Benjamin Biedermann and Kevin Hsu and Bernd Sumpf and Karl-Heinz Hasler and G{\"o}tz Erbert and Ole B. Jensen and Christian Pedersen and Robert Huber and Peter E. Andersen},
title = {{FDML swept source at 1060 nm using a tapered amplifier}},
volume = {7554},
booktitle = {Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XIV},
editor = {Joseph A. Izatt and James G. Fujimoto and Valery V. Tuchin},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {75541H},
abstract = {We present a novel frequency-swept light source working at 1060nm that utilizes a tapered amplifier as gain
medium. These devices feature significantly higher saturation power than conventional semiconductor optical
amplifiers and can thus improve the limited output power of swept sources in this wavelength range. We
demonstrate that a tapered amplifier can be integrated into a fiber-based swept source and allows for high-speed
FDML operation. The developed light source operates at a sweep rate of 116kHz with an effective average
output power in excess of 30mW. With a total sweep range of 70 nm an axial resolution of 15 μm in air (~11μm in tissue) for OCT applications can be achieved.},
keywords = {optical coherence tomography, swept source, tunable laser, tapered amplifier, fourier domain mode-locking},
year = {2010},
doi = {10.1117/12.842011},
URL = {https://doi.org/10.1117/12.842011}
}

@article{Jirauschek:09,
author = {Christian Jirauschek and Benjamin Biedermann and Robert Huber},
journal = {Opt. Express},
keywords = {Laser theory; Lasers, tunable; Optical coherence tomography; Fourier domain mode locking; Laser modes; Laser sources; Mode locking; Optical amplifiers; Spontaneous emission},
number = {26},
pages = {24013--24019},
publisher = {Optica Publishing Group},
title = {A theoretical description of Fourier domain mode locked lasers},
volume = {17},
month = {Dec},
year = {2009},
url = {https://opg.optica.org/oe/abstract.cfm?URI=oe-17-26-24013},
doi = {10.1364/OE.17.024013},
abstract = {The first theoretical model of Fourier domain mode locking operation is presented. A specially tailored dynamic equation in a moving spectral reference frame is derived, enabling efficient numerical treatment, despite the broad laser spectrum and the extremely long cavity. The excellent agreement of the presented theory with experiment over a wide range of operation parameters enables a quantitative assessment of the relevant physical effects, such as the spectral loss modulation and gain saturation dynamics, amplified spontaneous emission, linewidth enhancement, and self-phase modulation.},
}

@article{Wieser:09,
author = {Wolfgang Wieser and Benjamin R. Biedermann and Thomas Klein and Christoph M. Eigenwillig and Robert Huber},
journal = {Opt. Express},
keywords = {Fiber characterization; Fiber properties; Fibers, single-mode; Optical communications; Lasers, tunable; Dispersion; Optical standards and testing; Lasers, fiber; Fiber optic amplifiers; Laser modes; Laser sources; Mode locking; Optical networks; Thermal effects},
number = {25},
pages = {22871--22878},
publisher = {Optica Publishing Group},
title = {Ultra-rapid dispersion measurement in optical fibers},
volume = {17},
month = {Dec},
year = {2009},
url = {https://opg.optica.org/oe/abstract.cfm?URI=oe-17-25-22871},
doi = {10.1364/OE.17.022871},
abstract = {We present a novel method to measure the chromatic dispersion of fibers with lengths of several kilometers. The technique is based on a rapidly swept Fourier domain mode locked laser driven at 50kHz repetition rate. Amplitude modulation with 400MHz and phase analysis yield the dispersion values over a 130nm continuous wavelength tuning range covering C and L band. The high acquisition speed of 10{\textmu}s for individual wavelength-resolved traces $\Delta$t($\lambda$) can reduce effects caused by thermal drift and acoustic vibrations. It enables real-time monitoring with update rates \>100Hz even when averaging several hundred acquisitions for improved accuracy.},
}

@INPROCEEDINGS{5343314,
  author={Huber, Robert},
  booktitle={2009 IEEE LEOS Annual Meeting Conference Proceedings}, 
  title={Advances in Fourier domain OCT}, 
  year={2009},
  volume={},
  number={},
  pages={201-202},
  abstract={In optical coherence tomography, the introduction of so called ldquoFrequency Domainrdquo techniques, i.e. spectrally resolved detection, had a dramatic impact on these biomedical imaging systems. The current status and future developments will be discussed.},
  keywords={},
  doi={10.1109/LEOS.2009.5343314},
  ISSN={1092-8081},
  month={Oct},}

@article{Eigenwillig:09,
author = {Christoph M. Eigenwillig and Benjamin R. Biedermann and Wolfgang Wieser and Robert Huber},
journal = {Opt. Express},
keywords = {Noise in imaging systems; Optical coherence tomography; Fabry-Perot; Filters; Interferometry; Lasers, tunable; Fiber Bragg grating sensors; Image quality; Light properties; Light sources; Medical imaging; Mode locking},
number = {21},
pages = {18794--18807},
publisher = {Optica Publishing Group},
title = {Wavelength swept amplified spontaneous emission source},
volume = {17},
month = {Oct},
year = {2009},
url = {https://opg.optica.org/oe/abstract.cfm?URI=oe-17-21-18794},
doi = {10.1364/OE.17.018794},
abstract = {We present a new, alternative approach to realize a wavelength swept light source with no fundamental limit to sweep speed. Amplified spontaneous emission (ASE) light alternately passes a cascade of optical gain elements and tunable optical bandpass filters. We show that for high sweep speeds, the control signal for the different filters has to be applied with a defined, precise phase delay on the order of nanoseconds, to compensate for the light propagation time between the filters and ensure optimum operation. At a center wavelength of 1300 nm sweep rates of 10 kHz, 100 kHz and 340 kHz over a sweep range of 100 nm full width and an average power of 50 mW are demonstrated. For application in optical coherence tomography (OCT), an axial resolution of 12 {\textmu}m (air), a sensitivity of 120 dB (50 mW) and a dynamic range of 50 dB are achieved and OCT imaging is demonstrated. Performance parameters like coherence properties and relative intensity noise (RIN) are quantified, discussed and compared to the performance of Fourier Domain Mode Locked (FDML) lasers. Physical models for the observed difference in performance are provided.},
}

@article{Leonhardt:09,
author = {Rainer Leonhardt and Benjamin R. Biedermann and Wolfgang Wieser and Robert Huber},
journal = {Opt. Express},
keywords = {Fiber optics amplifiers and oscillators; Fibers, erbium; Lasers, tunable; Nonlinear optics, fibers; Nonlinear optics, four-wave mixing; Wavelength conversion devices ; Four wave mixing; Fourier domain mode locking; Laser sources; Optical coherence tomography; Optical frequency conversion; Semiconductor optical amplifiers},
number = {19},
pages = {16801--16808},
publisher = {Optica Publishing Group},
title = {Nonlinear optical frequency conversion of an amplified Fourier Domain Mode Locked (FDML) laser},
volume = {17},
month = {Sep},
year = {2009},
url = {https://opg.optica.org/oe/abstract.cfm?URI=oe-17-19-16801},
doi = {10.1364/OE.17.016801},
abstract = {We report on the highly efficient non-linear optical frequency conversion of the wavelength swept output from a Fourier Domain Mode Locked (FDML) laser. Different concepts for power scaling of FDML lasers by post-amplification with active fibers are presented. A two-stage post-amplification of an FDML laser with an amplification factor of 300 up to a peak power of 1.5 W is used to supply sufficient power levels for non-linear conversion. Using a single-mode dispersion shifted fiber (DSF), we convert this amplified output that covers the region between 1541 nm and 1545 nm to a wavelength range from 1572 nm to 1663 nm via modulation instability (MI). For this four wave mixing process we observe an efficiency of ~40\%. The anti-Stokes signal between 1435 nm and 1516 nm was observed with lower conversion efficiency. In addition to shifting the wavelength, the effect of MI also enables a substantial increase in the wavelength sweep rate of the FDML laser by a factor of ~50 to 0.55 nm/ns.},
}