@article{Eigenwillig:09,
author = {Christoph M. Eigenwillig and Wolfgang Wieser and Benjamin R. Biedermann and Robert Huber},
journal = {Opt. Lett.},
keywords = {Coherence imaging; Optical coherence tomography; Three-dimensional image acquisition; Lasers, tunable; Medical and biological imaging; Optical coherence tomography; Fourier domain mode locking; Laser operation; Laser sources; Laser systems; Mode locking; Optical coherence tomography},
number = {6},
pages = {725--727},
publisher = {Optica Publishing Group},
title = {Subharmonic Fourier domain mode locking},
volume = {34},
month = {Mar},
year = {2009},
url = {https://opg.optica.org/ol/abstract.cfm?URI=ol-34-6-725},
doi = {10.1364/OL.34.000725},
abstract = {We demonstrate a subharmonically Fourier domain mode-locked wavelength-swept laser source with a substantially reduced cavity fiber length. In contrast to a standard Fourier domain mode-locked configuration, light is recirculated repetitively in the delay line with the optical bandpass filter used as switch. The laser has a fundamental optical round trip frequency of 285 kHz and can be operated at integer fractions thereof (subharmonics). Sweep ranges up to 95 nm full width centred at 1317 nm are achieved at the 1/5th subharmonic. A maximum sensitivity of 116 dB and an axial resolution of 12 $\mu$m in air are measured at an average sweep power of 12 mW. A sensitivity roll-off of 11 dB over 4 mm and 25 dB over 10 mm is observed and optical coherence tomography imaging is demonstrated. Besides the advantage of a reduced fiber length, subharmonic Fourier domain mode locking (shFDML) enables simple scaling of the sweep speed by extracting light from the delay part of the resonator. A sweep rate of 570 kHz is achieved. Characteristic features of shFDML operation, such as power leakage during fly-back and cw breakthrough, are investigated.},
}

@inproceedings{10.1117/12.808555,
author = {Karol Karnowski and Michalina Gora and Bartlomiej Kaluzny and Robert Huber and Maciej Szkulmowski and Andrzej Kowalczyk and Maciej Wojtkowski},
title = {{Swept source OCT imaging of human anterior segment at 200 kHz}},
volume = {7163},
booktitle = {Ophthalmic Technologies XIX},
editor = {Fabrice Manns and Per G. S{\"o}derberg and Arthur Ho},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {716308},
abstract = {We present applicability of the high speed swept-source optical coherence tomography for in vivo imaging of the anterior segment of the human eye. Three dimensional imaging of the cornea with reduced motion artifacts is possible by using swept source with Fourier domain mode locking operating at 200kHz with 1300nm central wavelength. High imaging speeds allow for assessment of anterior and posterior corneal topography and generation of thickness and elevation maps.},
keywords = {Optical Coherence Tomography, Fourier domain detection methods, swept source OCT, anterior segment of the eye},
year = {2009},
doi = {10.1117/12.808555},
URL = {https://doi.org/10.1117/12.808555}
}

@Misc{HU_2009_Huber_b,
  Title                    = {{Fourier domain mode locking: new lasers for optical coherence tomography}},

  Author                   = {Huber, Robert},
  Year                     = {2009},

  Booktitle                = {SPIE Newsroom},
  Doi                      = {10.1117/2.1200901.1440},
  ISSN                     = {18182259},
keywords = {AG-Huber_FDML, AG-Huber_OCT},
  Url                      = {http://www.spie.org/x33321.xml}
}

@article{Klein:08,
author = {Thomas Klein and Wolfgang Wieser and Benjamin R. Biedermann and Christoph M. Eigenwillig and Gesa Palte and Robert Huber},
journal = {Opt. Lett.},
keywords = {Optical coherence tomography; Lasers, fiber; Lasers, Raman; Lasers, tunable; Optical coherence tomography; Laser operation; Mode locking; Optical coherence tomography; Optical components; Raman fiber lasers; Semiconductor lasers},
number = {23},
pages = {2815--2817},
publisher = {Optica Publishing Group},
title = {Raman-pumped Fourier-domain mode-locked laser: analysis of operation and application for optical coherence tomography},
volume = {33},
month = {Dec},
year = {2008},
url = {https://opg.optica.org/ol/abstract.cfm?URI=ol-33-23-2815},
doi = {10.1364/OL.33.002815},
abstract = {We demonstrate a Raman-pumped Fourier-domain mode-locked (FDML) fiber laser and optical coherence tomography imaging with this source. The wavelength sweep range of only 30 nm centered around 1550 nm results in limited axial resolution, hence a nonbiological sample is imaged. An output power of 1.9 mW was achieved at a sweep rate of 66 kHz and a maximum ranging depth of ~2.5 cm. Roll-off characteristics are found to be similar to FDML lasers with semiconductor optical amplifiers as gain media. The application of Raman gain also enables unperturbed cavity ring-down experiments in FDML lasers for the first time, providing direct access to the photon lifetime in the laser cavity. Good agreement with nonswept cw operation is proof of the stationary operation of FDML lasers.},
}

@article{10.1167/iovs.08-2127,
    author = {Srinivasan, Vivek J. and Adler, Desmond C. and Chen, Yueli and Gorczynska, Iwona and Huber, Robert and Duker, Jay S. and Schuman, Joel S. and Fujimoto, James G.},
    title = "{Ultrahigh-Speed Optical Coherence Tomography for Three-Dimensional and En Face Imaging of the Retina and Optic Nerve Head}",
    journal = {Investigative Ophthalmology & Visual Science},
    volume = {49},
    number = {11},
    pages = {5103-5110},
    year = {2008},
    month = {11},
    abstract = "{  purpose. To demonstrate ultrahigh-speed optical coherence tomography (OCT) imaging of the retina and optic nerve head at 249,000 axial scans per second and a wavelength of 1060 nm. To investigate methods for visualization of the retina, choroid, and optic nerve using high-density sampling enabled by improved imaging speed.  methods. A swept-source OCT retinal imaging system operating at a speed of 249,000 axial scans per second was developed. Imaging of the retina, choroid, and optic nerve were performed. Display methods such as speckle reduction, slicing along arbitrary planes, en face visualization of reflectance from specific retinal layers, and image compounding were investigated.  results. High-definition and three-dimensional (3D) imaging of the normal retina and optic nerve head were performed. Increased light penetration at 1060 nm enabled improved visualization of the choroid, lamina cribrosa, and sclera. OCT fundus images and 3D visualizations were generated with higher pixel density and less motion artifacts than standard spectral/Fourier domain OCT. En face images enabled visualization of the porous structure of the lamina cribrosa, nerve fiber layer, choroid, photoreceptors, RPE, and capillaries of the inner retina.  conclusions. Ultrahigh-speed OCT imaging of the retina and optic nerve head at 249,000 axial scans per second is possible. The improvement of ∼5 to 10× in imaging speed over commercial spectral/Fourier domain OCT technology enables higher density raster scan protocols and improved performance of en face visualization methods. The combination of the longer wavelength and ultrahigh imaging speed enables excellent visualization of the choroid, sclera, and lamina cribrosa. }",
    issn = {1552-5783},
    doi = {10.1167/iovs.08-2127},
    url = {https://doi.org/10.1167/iovs.08-2127},
    eprint = {https://arvojournals.org/arvo/content\_public/journal/iovs/932946/z7g01108005103.pdf},
}

@article{Biedermann:08,
author = {Benjamin R. Biedermann and Wolfgang Wieser and Christoph M. Eigenwillig and Gesa Palte and Desmond C. Adler and Vivek J. Srinivasan and James G. Fujimoto and Robert Huber},
journal = {Opt. Lett.},
keywords = {Coherence imaging; Optical coherence tomography; Three-dimensional image acquisition; Lasers, tunable; Medical and biological imaging; Optical coherence tomography; Analog to digital converters; Interference; Laser sources; Medical imaging; Mode locking; Optical coherence tomography},
number = {21},
pages = {2556--2558},
publisher = {Optica Publishing Group},
title = {Real time en face Fourier-domain optical coherence tomography with direct hardware frequency demodulation},
volume = {33},
month = {Nov},
year = {2008},
url = {https://opg.optica.org/ol/abstract.cfm?URI=ol-33-21-2556},
doi = {10.1364/OL.33.002556},
abstract = {We demonstrate en face swept source optical coherence tomography (ss-OCT) without requiring a Fourier transformation step. The electronic optical coherence tomography (OCT) interference signal from a k-space linear Fourier domain mode-locked laser is mixed with an adjustable local oscillator, yielding the analytic reflectance signal from one image depth for each frequency sweep of the laser. Furthermore, a method for arbitrarily shaping the spectral intensity profile of the laser is presented, without requiring the step of numerical apodization. In combination, these two techniques enable sampling of the in-phase and quadrature signal with a slow analog-to-digital converter and allow for real-time display of en face projections even for highest axial scan rates. Image data generated with this technique is compared to en face images extracted from a three-dimensional OCT data set. This technique can allow for real-time visualization of arbitrarily oriented en face planes for the purpose of alignment, registration, or operator-guided survey scans while simultaneously maintaining the full capability of high-speed volumetric ss-OCT functionality.},
}

@article{Eigenwillig:08,
author = {Christoph M. Eigenwillig and Benjamin R. Biedermann and Gesa Palte and Robert Huber},
journal = {Opt. Express},
keywords = {Optical coherence tomography; Three-dimensional image acquisition; Interferometry; Lasers, tunable; Medical and biological imaging; Optical coherence tomography; Image quality; Laser modes; Laser sources; Medical imaging; Mode locking; Swept lasers},
number = {12},
pages = {8916--8937},
publisher = {Optica Publishing Group},
title = {K-space linear Fourier domain mode locked laser and applications for optical coherence tomography},
volume = {16},
month = {Jun},
year = {2008},
url = {https://opg.optica.org/oe/abstract.cfm?URI=oe-16-12-8916},
doi = {10.1364/OE.16.008916},
abstract = {We report on a Fourier Domain Mode Locked (FDML) wavelength swept laser source with a highly linear time-frequency sweep characteristic and demonstrate OCT imaging without k-space resampling prior to Fourier transformation. A detailed theoretical framework is provided and different strategies how to determine the optimum drive waveform of the piezo-electrically actuated optical bandpass-filter in the FDML laser are discussed. An FDML laser with a relative optical frequency deviation $\Delta$$\nu$/$\nu$ smaller than 8{\textperiodcentered}10-5 over a 100 nm spectral bandwidth at 1300 nm is presented, enabling high resolution OCT over long ranging depths. Without numerical time-to-frequency resampling and without spectral apodization a sensitivity roll off of 4 dB over 2 mm, 12.5 dB over 4 mm and 26.5 dB over 1 cm at 3.5 {\textmu}s sweep duration and 106.6 dB maximum sensitivity at 9.2 mW average power is achieved. The axial resolution in air degrades from 14 to 21 {\textmu}m over 4 mm imaging depth. The compensation of unbalanced dispersion in the OCT sample arm by an adapted tuning characteristic of the source is demonstrated. Good stability of the system without feedback-control loops is observed over hours.},
}

@INPROCEEDINGS{4571888,
  author={Jirauschek, Christian and Eigenwillig, Christoph and Biedermann, Benjamin and Huber, Robert},
  booktitle={2008 Conference on Lasers and Electro-Optics and 2008 Conference on Quantum Electronics and Laser Science}, 
  title={Fourier domain mode locking theory}, 
  year={2008},
  volume={},
  number={},
  pages={1-2},
  abstract={We present a theoretical model for the recently developed Fourier domain mode locked (FDML) lasers. The good agreement with experiment provides valuable insights into the mechanism of FDML operation.},
  keywords={},
  doi={10.1109/CLEO.2008.4551638},
  ISSN={},
  month={May},}

@INPROCEEDINGS{4571261,
  author={Eigenwillig, Christoph and Biedermann, Benjamin and Huber, Robert},
  booktitle={2008 Conference on Lasers and Electro-Optics and 2008 Conference on Quantum Electronics and Laser Science}, 
  title={Optical coherence tomography imaging with k-space linear fourier domain mode locked lasers}, 
  year={2008},
  volume={},
  number={},
  pages={1-2},
  abstract={We report on a Fourier Domain Mode Locked wavelength swept laser source with a highly linear time-frequency sweep characteristic and demonstrate OCT imaging without k-space resampling prior to Fourier transformation with this source.},
  keywords={},
  doi={10.1109/CLEO.2008.4551011},
  ISSN={},
  month={May},}

@article{ANDREWS2008441,
title = {High-resolution optical coherence tomography imaging of the living kidney},
journal = {Laboratory Investigation},
volume = {88},
number = {4},
pages = {441-449},
year = {2008},
issn = {0023-6837},
doi = {https://doi.org/10.1038/labinvest.2008.4},
url = {https://www.sciencedirect.com/science/article/pii/S0023683722019158},
author = {Peter M Andrews and Yu Chen and Maristela L Onozato and Shu-Wei Huang and Desmond C Adler and Robert A Huber and James Jiang and Scott E Barry and Alex E Cable and James G Fujimoto},
keywords = {ischemia, kidney, optical coherence tomography (OCT), renal pathology, three-dimensional imaging, renal transplantation},
abstract = {Optical coherence tomography (OCT) is a rapidly emerging imaging modality that can provide non-invasive, cross-sectional, high-resolution images of tissue morphology in situ and in real-time. In the present series of studies, we used a high-speed OCT imaging system equipped with a frequency-swept laser light source (1.3 μm wavelength) to study living kidneys in situ. Adult, male Munich–Wistar rats were anesthetized, a laparotomy was performed and the living kidneys were exposed for in situ observation. We observed the kidneys prior to, during and following exposure to renal ischemia induced by clamping the renal artery. The effects of intravenous mannitol infusion (1.0 ml of 25%) prior to and during renal ischemia were also studied. Finally, living kidneys were flushed with a renal preservation solution, excised and observed while being stored at 0–4°C. Three-dimensional OCT data sets enabled visualization of the morphology of the uriniferous tubules and the renal corpuscles. When renal ischemia was induced, OCT revealed dramatic shrinkage of tubular lumens due to swelling of the lining epithelium. Three-dimensional visualization and volumetric rendering software provided an accurate evaluation of volumetric changes in tubular lumens in response to renal ischemia. Observations of kidneys flushed with a renal preservation solution and stored at 0–4°C also revealed progressive and significant loss of tubular integrity over time. Intravenous infusion of mannitol solution resulted in thinning of the tubular walls and an increase in the tubular lumen diameters. Mannitol infusion also prevented the cell swelling that otherwise resulted in shrinkage of proximal tubule lumens during ischemia. We conclude that OCT represents an exciting new approach to visualize, in real-time, pathological changes in the living kidney in a non-invasive fashion. Possible clinical applications are discussed.}
}

@inproceedings{10.1117/12.761850,
author = {Desmond C. Adler and Yu Chen and Robert Huber and Joseph Schmitt and James Connolly and James G. Fujimoto},
title = {{In vivo endomicroscopy using three-dimensional optical coherence tomography and Fourier domain mode locked lasers}},
volume = {6847},
booktitle = {Coherence Domain Optical Methods and Optical Coherence Tomography in Biomedicine XII},
editor = {Joseph A. Izatt and James G. Fujimoto and Valery V. Tuchin},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {684708},
abstract = {We report an endoscopic optical coherence tomography (OCT) system based on a Fourier Domain Mode Locked
(FDML) laser, a novel data acquisition (DAQ) system with optical frequency clocking, and a high-speed spiralscanning
fiber probe. The system is capable of acquiring three-dimensional (3D) in vivo datasets at 100,000 axial
lines/s and 50 frames/s, enabled by the high sweep rates of the FDML laser and the efficient data processing of
the DAQ system. This high imaging rate allows densely-sampled 3D datasets to be acquired, giving a resolvable
feature size of 9 &mgr;m x 20 &mgr;m x 7 &mgr;m (transverse x longitudinal x axial, XYZ). In vivo 3D endomicroscopy is
demonstrated in the rabbit colon, where individual colonic crypts are clearly visualized and measured. With
further improvements in DAQ technology, the imaging speed will be scalable to the hundreds of thousands of
axial lines/s supported by FDML lasers.},
keywords = {Optical coherence tomography, Endoscopic microscopy, Fourier Domain Mode Locked lasers, FDML, Three dimensional microscopy, In vivo microscopy, Biomedical optics, Swept source optical coherence tomography},
year = {2008},
doi = {10.1117/12.761850},
URL = {https://doi.org/10.1117/12.761850}
}

@article{Bajraszewski:08,
author = {Tomasz Bajraszewski and Maciej Wojtkowski and Maciej Szkulmowski and Anna Szkulmowska and Robert Huber and Andrzej Kowalczyk},
journal = {Opt. Express},
keywords = {Optical coherence tomography; Fabry-Perot; Image reconstruction techniques; Multiframe image processing ; Frequency combs; Medical imaging; Ophthalmic imaging; Optical coherence tomography; Swept sources; Three dimensional imaging},
number = {6},
pages = {4163--4176},
publisher = {Optica Publishing Group},
title = {Improved spectral optical coherence tomography using optical frequency comb},
volume = {16},
month = {Mar},
year = {2008},
url = {https://opg.optica.org/oe/abstract.cfm?URI=oe-16-6-4163},
doi = {10.1364/OE.16.004163},
abstract = {We identify and analyze factors influencing sensitivity drop-off in Spectral OCT and propose a system employing an Optical Frequency Comb (OFC) to verify this analysis. Spectral Optical Coherence Tomography using a method based on an optical frequency comb is demonstrated. Since the spectrum sampling function is determined by the comb rather than detector pixel distribution, this method allows to overcome limitations of high resolution Fourier-domain OCT techniques. Additionally, the presented technique also enables increased imaging range while preserving high axial resolution. High resolution cross-sectional images of biological samples obtained with the proposed technique are presented.},
}

@article{Adler:08,
author = {Desmond C. Adler and Shu-Wei Huang and Robert Huber and James G. Fujimoto},
journal = {Opt. Express},
keywords = {Optical coherence tomography; Phase measurement; Lasers, tunable; Nanomaterials; Laser beams; Medical imaging; Multimode lasers; Optical Doppler tomography; Phase modulation; Single mode lasers},
number = {7},
pages = {4376--4393},
publisher = {Optica Publishing Group},
title = {Photothermal detection of gold nanoparticles using phase-sensitive optical coherence tomography},
volume = {16},
month = {Mar},
year = {2008},
url = {https://opg.optica.org/oe/abstract.cfm?URI=oe-16-7-4376},
doi = {10.1364/OE.16.004376},
abstract = {The detection of a gold nanoparticle contrast agent is demonstrated using a photothermal modulation technique and phase sensitive optical coherence tomography (OCT). A focused beam from a laser diode at 808 nm is modulated at frequencies of 500 Hz--60 kHz while irradiating a solution containing nanoshells. Because the nanoshells are designed to have a high absorption coefficient at 808 nm, the laser beam induces small-scale localized temperature oscillations at the modulation frequency. These temperature oscillations result in optical path length changes that are detected by a phase-sensitive, swept source OCT system. The OCT system uses a double-buffered Fourier domain mode locked (FDML) laser operating at a center wavelength of 1315 nm and a sweep rate of 240 kHz. High contrast is observed between phantoms containing nanoshells and phantoms without nanoshells. This technique represents a new method for detecting gold nanoparticle contrast agents with excellent signal-to-noise performance at high speeds using OCT.},
}

@article{HU_2007_Adlera,
  Title                    = {Three-dimensional endomicroscopy using optical coherence tomography},
  Author                   = {Adler, Desmond C. and Chen, Yu and Huber, Robert and Schmitt, Joseph and Connolly, James and Fujimoto, James G.},
  Journal                  = {Nature Photonics},
  Year                     = {2007},
  Month                    = nov,
  Number                   = {12},
  Pages                    = {709--716},
  Volume                   = {1},
  Doi                      = {10.1038/nphoton.2007.228},
Timestamp                = {2014.11.20},
  ISSN                     = {1749-4885}
}

@article{Kranendonk:07,
author = {Laura A. Kranendonk and Xinliang An and Andrew W. Caswell and Randy E. Herold and Scott T. Sanders and Robert Huber and James G. Fujimoto and Yasuhiro Okura and Yasuhiro Urata},
journal = {Opt. Express},
keywords = {Spectrometers and spectroscopic instrumentation; Lasers, tunable; Spectroscopy, fluorescence and luminescence; Absorption; Spectroscopy, diode lasers; Spectroscopy, infrared; Fourier transform spectroscopy; Laser modes; Laser sources; Laser spectroscopy; Molecular spectra; Optical coherence tomography},
number = {23},
pages = {15115--15128},
publisher = {Optica Publishing Group},
title = {High speed engine gas thermometry by Fourier-domain mode-locked laser absorption spectroscopy},
volume = {15},
month = {Nov},
year = {2007},
url = {https://opg.optica.org/oe/abstract.cfm?URI=oe-15-23-15115},
doi = {10.1364/OE.15.015115},
abstract = {We present a novel method for low noise, high-speed, real-time spectroscopy to monitor molecular absorption spectra. The system is based on a rapidly swept, narrowband CW Fourier-domain mode-locked (FDML) laser source for spectral encoding in time and an optically time-multiplexed split-pulse data acquisition system for improved noise performance and sensitivity. An acquisition speed of $\sim$100 kHz, a spectral resolution better than 0.1 nm over a wavelength range of $\sim$1335--1373 nm and a relative noise level of $\sim$5 mOD ($\sim$1\% minimum detectable base-e absorbance) are achieved. The system is applied for crank-angle-resolved gas thermometry by H2O absorption spectroscopy in an engine motoring at 600 and 900 rpm with a precision of $\sim$1\%. Influences of various noise sources such as laser phase and intensity noise, trigger and synchronization jitter in the electronic detection system, and the accuracy of available H2O absorption databases are discussed.},
}

@article{Adler:07,
author = {Desmond C. Adler and Jens Stenger and Iwona Gorczynska and Henry Lie and Teri Hensick and Ron Spronk and Stephan Wolohojian and Narayan Khandekar and James Y. Jiang and Scott Barry and Alex E. Cable and Robert Huber and James G. Fujimoto},
journal = {Opt. Express},
keywords = {Optical coherence tomography; Photography; Three-dimensional image acquisition; Optical inspection; Lasers, tunable; Three-dimensional microscopy; Digital photography; Fourier domain mode locking; Image processing; Speckle interferometry; Three dimensional imaging; Three dimensional measurement},
number = {24},
pages = {15972--15986},
publisher = {Optica Publishing Group},
title = {Comparison of three-dimensional optical coherence tomography and high resolution photography for art conservation studies},
volume = {15},
month = {Nov},
year = {2007},
url = {https://opg.optica.org/oe/abstract.cfm?URI=oe-15-24-15972},
doi = {10.1364/OE.15.015972},
abstract = {Gold punchwork and underdrawing in Renaissance panel paintings are analyzed using both three-dimensional swept source/Fourier domain optical coherence tomography (3D-OCT) and high resolution digital photography. 3D-OCT can generate en face images with micrometer-scale resolutions at arbitrary sectioning depths, rejecting out-of-plane light by coherence gating. Therefore 3D-OCT is well suited for analyzing artwork where a surface layer obscures details of interest. 3D-OCT also enables cross-sectional imaging and quantitative measurement of 3D features such as punch depth, which is beneficial for analyzing the tools and techniques used to create works of art. High volumetric imaging speeds are enabled by the use of a Fourier domain mode locked (FDML) laser as the 3D-OCT light source. High resolution infrared (IR) digital photography is shown to be particularly useful for the analysis of underdrawing, where the materials used for the underdrawing and paint layers have significantly different IR absorption properties. In general, 3D-OCT provides a more flexible and comprehensive analysis of artwork than high resolution photography, but also requires more complex instrumentation and data analysis.},
}

@article{Huber:07,
author = {R. Huber and D. C. Adler and V. J. Srinivasan and J. G. Fujimoto},
journal = {Opt. Lett.},
keywords = {Optical coherence tomography; Lasers, tunable; Medical and biological imaging; Amplified spontaneous emission; Fourier domain mode locking; Image quality; Optical coherence tomography; Retina; Retina scanning},
number = {14},
pages = {2049--2051},
publisher = {Optica Publishing Group},
title = {Fourier domain mode locking at 1050 nm for ultra-high-speed optical coherence tomography of the human retina at 236,000 axial scans per second},
volume = {32},
month = {Jul},
year = {2007},
url = {https://opg.optica.org/ol/abstract.cfm?URI=ol-32-14-2049},
doi = {10.1364/OL.32.002049},
abstract = {A Fourier domain mode-locked (FDML) laser at 1050 nm for ultra-high-speed optical coherence tomography (OCT) imaging of the human retina is demonstrated. Achievable performance, physical limitations, design rules, and scaling principles for FDML operation and component choice in this wavelength range are discussed. The fiber-based FDML laser operates at a sweep rate of 236 kHz over a 63 nm tuning range, with 7 mW average output power. Ultra-high-speed retinal imaging is demonstrated at 236,000 axial scans per second. This represents a speed improvement of ~10{\texttimes} over typical high-speed OCT systems, paving the way for densely sampled volumetric data sets and new imaging protocols.},
}

@inproceedings{Huber:07,
author = {Robert Huber and Vivek J. Srinivasan and Desmond C. Adler and I. Gorczynska and James G. Fujimoto},
booktitle = {Conference on Lasers and Electro-Optics/Quantum Electronics and Laser Science Conference and Photonic Applications Systems Technologies},
journal = {Conference on Lasers and Electro-Optics/Quantum Electronics and Laser Science Conference and Photonic Applications Systems Technologies},
keywords = {General physics; General science; Fourier domain mode locking; Image quality; In vivo imaging; Laser sources; Ophthalmic imaging; Optical coherence tomography},
pages = {CThAA5},
publisher = {Optica Publishing Group},
title = {Fourier Domain Mode Locking (FDML) in the non-zero dispersion regime: A laser for ultrahigh-speed retinal OCT imaging at 236kHz line rate},
year = {2007},
url = {https://opg.optica.org/abstract.cfm?URI=CLEO-2007-CThAA5},
abstract = {Fourier Domain Mode Locking (FDML) in the 1070nm wavelength range is investigated. Problems, design rules and the performance of an FDML laser with a dispersive cavity are discussed. Retinal OCT imaging at 236kHz is demonstrated.},
}

@INPROCEEDINGS{4452406,
  author={Adler, Desmond C. and Huber, Robert and Fujimoto, James G.},
  booktitle={2007 Conference on Lasers and Electro-Optics (CLEO)}, 
  title={Optical Coherence Tomography Phase Microscopy Using Buffered Fourier Domain Mode Locked (FDML) Lasers at up to 370,000 Lines per Second}, 
  year={2007},
  volume={},
  number={},
  pages={1-2},
  abstract={Buffered FDML lasers are applied for phase-sensitive sub-nanometer OCT phase microscopy and dynamic surface displacement measurements at speeds up to 370,000 axial lines per second. Excellent phase stability is demonstrated at high speeds.},
  keywords={},
  doi={10.1109/CLEO.2007.4452406},
  ISSN={2160-9004},
  month={May},}

@article{Huang:07,
author = {Shu-Wei Huang and Aaron D. Aguirre and Robert A. Huber and Desmond C. Adler and James G. Fujimoto},
journal = {Opt. Express},
keywords = {Optical coherence tomography; Lasers, tunable; Medical and biological imaging; Confocal microscopy; Three-dimensional microscopy; Image quality; Laser sources; Mode locking; Optical delay lines; Swept sources; Three dimensional imaging},
number = {10},
pages = {6210--6217},
publisher = {Optica Publishing Group},
title = {Swept source optical coherence microscopy using a Fourier domain mode-locked laser},
volume = {15},
month = {May},
year = {2007},
url = {https://opg.optica.org/oe/abstract.cfm?URI=oe-15-10-6210},
doi = {10.1364/OE.15.006210},
abstract = {Swept source optical coherence microscopy (OCM) enables cellular resolution en face imaging as well as integration with optical coherence tomography (OCT) cross sectional imaging. A buffered Fourier domain mode-locked (FDML) laser light source provides high speed, three dimensional imaging. Image resolutions of 1.6 $\mu$m {\texttimes} 8 $\mu$m (transverse {\texttimes} axial) with a 220 $\mu$m {\texttimes} 220 $\mu$m field of view and sensitivity higher than 98 dB are achieved. Three dimensional cellular imaging is demonstrated in vivo in the Xenopus laevis tadpole and ex vivo in the rat kidney and human colon.},
}

@article{Jenkins:07,
author = {M. W. Jenkins and D. C. Adler and M. Gargesha and R. Huber and F. Rothenberg and J. Belding and M. Watanabe and D. L. Wilson and J. G. Fujimoto and A. M. Rollins},
journal = {Opt. Express},
keywords = {Three-dimensional image processing; Lasers; Medical and biological imaging; Optical coherence tomography; Developmental biology; Gated imaging; Imaging systems; Laser Doppler velocimetry; Laser modes; Mode locking},
number = {10},
pages = {6251--6267},
publisher = {Optica Publishing Group},
title = {Ultrahigh-speed optical coherence tomography imaging and visualization of the embryonic avian heart using a buffered Fourier Domain Mode Locked laser},
volume = {15},
month = {May},
year = {2007},
url = {https://opg.optica.org/oe/abstract.cfm?URI=oe-15-10-6251},
doi = {10.1364/OE.15.006251},
abstract = {The embryonic avian heart is an important model for studying cardiac developmental biology. The mechanisms that govern the development of a four-chambered heart from a peristaltic heart tube are largely unknown due in part to a lack of adequate imaging technology. Due to the small size and rapid motion of the living embryonic avian heart, an imaging system with high spatial and temporal resolution is required to study these models. Here, an optical coherence tomography (OCT) system using a buffered Fourier Domain Mode Locked (FDML) laser is applied for ultrahigh-speed non-invasive imaging of embryonic quail hearts at 100,000 axial scans per second. The high scan rate enables the acquisition of high temporal resolution 2D datasets (195 frames per second or 5.12 ms between frames) and 3D datasets (10 volumes per second). Spatio-temporal details of cardiac motion not resolvable using previous OCT technology are analyzed. Visualization and measurement techniques are developed to non-invasively observe and quantify cardiac motion throughout the brief period of systole (less than 50 msec) and diastole. This marks the first time that the preseptated embryonic avian heart has been imaged in 4D without the aid of gating and the first time it has been viewed in cross section during looping with extremely high temporal resolution, enabling the observation of morphological dynamics of the beating heart during systole.},
}

@article{Adler:07,
author = {Desmond C. Adler and Robert Huber and James G. Fujimoto},
journal = {Opt. Lett.},
keywords = {Optical coherence tomography; Phase measurement; Lasers, tunable; Amplified spontaneous emission; Laser sources; Mode locking; Optical coherence tomography; Phase measurement; Swept lasers},
number = {6},
pages = {626--628},
publisher = {Optica Publishing Group},
title = {Phase-sensitive optical coherence tomography at up to 370,000 lines per second using buffered Fourier domain mode-locked lasers},
volume = {32},
month = {Mar},
year = {2007},
url = {https://opg.optica.org/ol/abstract.cfm?URI=ol-32-6-626},
doi = {10.1364/OL.32.000626},
abstract = {Buffered Fourier domain mode-locked (FDML) lasers are demonstrated for dynamic phase-sensitive optical coherence tomography (OCT) and 3D OCT phase microscopy. Systems are operated at sweep speeds of 42, 117, and 370 kHz, and displacement sensitivities of 39, 52, and 102 pm are achieved, respectively. Sensitivities are comparable to spectrometer-based OCT phase microscopy systems, but much faster acquisition speeds are possible. An additional factor of sqrt 2 improvement in noise performance is observed for differential phase measurements, which is important for Doppler OCT. Dynamic measurements of piezoelectric transducer motion and static 3D OCT phase microscopy are demonstrated. Buffered FDML lasers provide excellent displacement sensitivities at extremely high sweep speeds.},
}

@inproceedings{10.1117/12.704084,
author = {Robert A. Huber and Desmond C. Adler and Vivek J. Srinivasan and Iwona M Gorczynska and James G. Fujimoto},
title = {{Fourier domain mode-locked (FDML) lasers at 1050 nm and 202,000 sweeps per second for OCT retinal imaging}},
volume = {6429},
booktitle = {Coherence Domain Optical Methods and Optical Coherence Tomography in Biomedicine XI},
editor = {James G. Fujimoto and Joseph A. Izatt and Valery V. Tuchin},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {642907},
abstract = {Retinal imaging ranks amongst the most important clinical applications for optical coherence
tomography (OCT) [1, 2]. The recent demonstration of increased sensitivity [3-6] in Fourier
Domain detection [7, 8] has opened the way for dramatically higher imaging speeds, up to axial
scan rates of several tens of kilohertz. However, these imaging speeds are still not sufficient for
high density 3D datasets and a further increase to several hundreds of kilohertz is necessary. In
this paper we demonstrate a swept laser source at 1050 nm with a sweep rate of 202 kHz. The
laser source provides ~10 mW average output power, up to 60 nm total sweep range and a
sensitivity roll off of less than 10 dB over 4 mm. In vivo 2D and 3D imaging of the human retina
at a record axial scan rate of 101 kHz is demonstrated. These results suggest that swept source
OCT has the potential to significantly outperform spectral/Fourier domain OCT for ophthalmic
imaging applications in the future.},
keywords = {tunable laser, optical coherence tomography, Fourier domain mode locking, swept source, OCT, FDML, retinal imaging, ophthalmic imaging},
year = {2007},
doi = {10.1117/12.704084},
URL = {https://doi.org/10.1117/12.704084}
}

@inproceedings{10.1117/12.704128,
author = {Desmond C. Adler and Robert Huber and James G. Fujimoto},
title = {{Phase-sensitive optical coherence tomography using buffered Fourier domain mode-locked lasers at up to 370,000 scans per second}},
volume = {6429},
booktitle = {Coherence Domain Optical Methods and Optical Coherence Tomography in Biomedicine XI},
editor = {James G. Fujimoto and Joseph A. Izatt and Valery V. Tuchin},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {64291L},
abstract = {Phase sensitive optical coherence tomography (OCT) can be used to obtain sub-nanometer
displacement measurements of biological and non-biological samples. This technique has many
applications, including detection of small amplitude surface motion, and high axial resolution OCT
phase microscopy. Doppler OCT is another type of phase sensitive imaging, where differential
phase measurements are used to detect fluid flow in biological specimens. For all types of phase
sensitive OCT, a light source with low phase noise is required in order to provide good
displacement sensitivity. High speed imaging is also necessary in order to minimize motion artifacts
and enable the detection of fast transient events. In this manuscript, buffered Fourier Domain Mode
Locked (FDML) lasers are demonstrated for ultrahigh-speed phase sensitive OCT detection. The
lasers are operated at sweep speeds of 42, 117, and 370 kHz, and displacement sensitivities of 39,
52, and 102 pm are achieved, respectively. These displacement sensitivities are comparable to
spectrometer-based phase sensitive OCT systems, but acquisition speeds 1.4 - 13x faster are
possible using buffered FDML lasers. An additional factor of √2 improvement in noise performance
is observed for differential phase measurements, which has important implications for Doppler
OCT. Dynamic measurements of rapid, small-amplitude piezoelectric transducer motion are
demonstrated. In general, buffered FDML lasers provide excellent displacement sensitivities at
extremely high sweep speeds for phase sensitive OCT measurements.},
keywords = {optical coherence tomography, OCT, optical coherence phase microscopy, swept source phase microscopy, doppler optical coherence tomography, frequency swept lasers, Fourier Domain Mode Locked lasers, FDML},
year = {2007},
doi = {10.1117/12.704128},
URL = {https://doi.org/10.1117/12.704128}
}

@article{Srinivasan:07,
author = {V. J. Srinivasan and R. Huber and I. Gorczynska and J. G. Fujimoto and J. Y. Jiang and P. Reisen and A. E. Cable},
journal = {Opt. Lett.},
keywords = {Optical coherence tomography; Lasers, tunable; Medical and biological imaging; Optical coherence tomography; Retina scanning; Semiconductor lasers; Semiconductor optical amplifiers; Spontaneous emission; Tunable lasers},
number = {4},
pages = {361--363},
publisher = {Optica Publishing Group},
title = {High-speed, high-resolution optical coherence tomography retinal imaging with a frequency-swept laser at 850 nm},
volume = {32},
month = {Feb},
year = {2007},
url = {https://opg.optica.org/ol/abstract.cfm?URI=ol-32-4-361},
doi = {10.1364/OL.32.000361},
abstract = {High-speed, high-resolution optical coherence tomography (OCT) imaging of the human retina is demonstrated using a frequency-swept laser at 850 nm. A compact external cavity semiconductor laser design, optimized for swept-source ophthalmic OCT, is described. The laser enables an effective 16 kHz sweep rate with \>10 mm coherence length and a tuning range of $\sim$35 nm full width at half-maximum, yielding an axial resolution of \<7 $\mu$m in tissue.},
}

@article{KRANENDONK2007783,
title = {Wavelength-agile H2O absorption spectrometer for thermometry of general combustion gases},
journal = {Proceedings of the Combustion Institute},
volume = {31},
number = {1},
pages = {783-790},
year = {2007},
issn = {1540-7489},
doi = {https://doi.org/10.1016/j.proci.2006.08.003},
url = {https://www.sciencedirect.com/science/article/pii/S1540748906002665},
author = {Laura A. Kranendonk and Robert Huber and James G. Fujimoto and Scott T. Sanders},
keywords = {Thermometry, Wavelength-agile, Absorption spectroscopy},
abstract = {Using a novel Fourier-domain mode-locking (FDML) laser scanning 1330–1380nm, we have developed a gas thermometer based on absorption spectroscopy that is appropriate for combustion gases at essentially arbitrary conditions. The path-integrated measurements are particularly useful in homogeneous environments, and here we present measurements in a controlled piston engine and a shock tube. Engine measurements demonstrate a RMS temperature precision of ±3% at 1500K and 200kHz bandwidth; the precision is improved dramatically by averaging. Initial shock tube measurements place the absolute accuracy of the thermometer within ∼2% to 1000K. The sensor performs best when significant H2O vapor is present, but requires only XH2OL>0.07cm at 300K, XH2OL>0.25cm at 1000K, or XH2OL>1.25cm at 3000K for 2% accurate thermometry, assuming a 4kHz measurement bandwidth (200kHz scans with 50 averages). The sensor also provides H2O mole fraction and shows potential for monitoring gas pressure based on the broadening of spectral features. To aid in designing other sensors based on high-temperature, high-pressure H2O absorption spectroscopy, a database of measured spectra is included.}
}

@article{Huber:06,
author = {Robert Huber and Desmond C. Adler and James G. Fujimoto},
journal = {Opt. Lett.},
keywords = {Optical coherence tomography; Lasers, tunable; Amplified spontaneous emission; Fourier domain mode locking; Image quality; Laser sources; Optical coherence tomography; Swept sources},
number = {20},
pages = {2975--2977},
publisher = {Optica Publishing Group},
title = {Buffered Fourier domain mode locking: unidirectional swept laser sources for optical coherence tomography imaging at 370,000 lines/s},
volume = {31},
month = {Oct},
year = {2006},
url = {https://opg.optica.org/ol/abstract.cfm?URI=ol-31-20-2975},
doi = {10.1364/OL.31.002975},
abstract = {We describe buffered Fourier domain mode locking (FDML), a technique for tailoring the output and multiplying the sweep rate of FDML lasers. Buffered FDML can be used to create unidirectional wavelength sweeps from the normal bidirectional sweeps in an FDML laser without sacrificing sweep rate. We also investigate the role of the laser source in dynamic range versus sensitivity performance in optical coherence tomography (OCT) imaging. Unidirectional sweep rates of 370 kHz over a 100 nm range at a center wavelength of 1300 nm are achieved. High-speed, swept-source OCT is demonstrated at record speeds of up to 370,000 axial scans per second.},
}

@article{LENZ2006255,
title = {First Steps of Retinal Photoisomerization in Proteorhodopsin},
journal = {Biophysical Journal},
volume = {91},
number = {1},
pages = {255-262},
year = {2006},
issn = {0006-3495},
doi = {https://doi.org/10.1529/biophysj.105.074690},
url = {https://www.sciencedirect.com/science/article/pii/S0006349506717258},
author = {Martin O. Lenz and Robert Huber and Bernhard Schmidt and Peter Gilch and Rolf Kalmbach and Martin Engelhard and Josef Wachtveitl},
abstract = {The early steps (<1ns) in the photocycle of the detergent solubilized proton pump proteorhodopsin are analyzed by ultrafast spectroscopic techniques. A comparison to the first primary events in reconstituted proteorhodopsin as well as to the well known archaeal proton pump bacteriorhodopsin is given. A dynamic Stokes shift observed in fs-time-resolved fluorescence experiments allows a direct observation of early motions on the excited state potential energy surface. The initial dynamics is dominated by sequentially emerging stretching (<150fs) and torsional (∼300fs) modes of the retinal. The different protonation states of the primary proton acceptor Asp-97 drastically affect the reaction rate and the overall quantum efficiencies of the isomerization reactions, mainly evidenced for time scales above 1ps. However, no major influence on the fast time scales (∼150fs) could be seen, indicating that the movement out of the Franck-Condon region is fairly robust to electrostatic changes in the retinal binding pocket. Based on fs-time-resolved absorption and fluorescence spectra, ground and exited state contributions can be disentangled and allow to construct a reaction model that consistently explains pH-dependent effects in solubilized and reconstituted proteorhodopsin.}
}

@INPROCEEDINGS{4627914,
  author={Huber, R. and Wojtkowski, M. and Fujimoto, J. G.},
  booktitle={2006 Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser Science Conference}, 
  title={Fourier Domain Mode Locking (FDML): Three-dimensional OCT imaging at 906 frames per second}, 
  year={2006},
  volume={},
  number={},
  pages={1-2},
  abstract={Fourier domain mode locking is a new operation regime of lasers. Highly chirped frequency swept waveforms rather than short pulses are generated. The mechanism and its application for ultrahigh-speed biomedical OCT imaging are discussed.},
  keywords={},
  doi={10.1109/CLEO.2006.4627914},
  ISSN={2160-9004},
  month={May},}

@article{Huber:06,
author = {R. Huber and M. Wojtkowski and J. G. Fujimoto},
journal = {Opt. Express},
keywords = {Optical coherence tomography; Lasers, tunable; Frequency modulated lasers; Full field optical coherence tomography; Laser operation; Light fields; Medical imaging; Mode locking},
number = {8},
pages = {3225--3237},
publisher = {Optica Publishing Group},
title = {Fourier Domain Mode Locking (FDML): A new laser operating regime and applications for optical coherence tomography},
volume = {14},
month = {Apr},
year = {2006},
url = {https://opg.optica.org/oe/abstract.cfm?URI=oe-14-8-3225},
doi = {10.1364/OE.14.003225},
abstract = {We demonstrate a new technique for frequency-swept laser operation--Fourier domain mode locking (FDML)--and its application for swept-source optical coherence tomography (OCT) imaging. FDML is analogous to active laser mode locking for short pulse generation, except that the spectrum rather than the amplitude of the light field is modulated. High-speed, narrowband optical frequency sweeps are generated with a repetition period equal to the fundamental or a harmonic of cavity round-trip time. An FDML laser is constructed using a long fiber ring cavity, a semiconductor optical amplifier, and a tunable fiber Fabry-Perot filter. Effective sweep rates of up to 290 kHz are demonstrated with a 105 nm tuning range at 1300 nm center wavelength. The average output power is 3 mW directly from the laser and 20 mW after post-amplification. Using the FDML laser for swept-source OCT, sensitivities of 108 dB are achieved and dynamic linewidths are narrow enough to enable imaging over a 7 mm depth with only a 7.5 dB decrease in sensitivity. We demonstrate swept-source OCT imaging with acquisition rates of up to 232,000 axial scans per second. This corresponds to 906 frames/second with 256 transverse pixel images, and 3.5 volumes/second with a 256{\texttimes}128{\texttimes}256 voxel element 3-D OCT data set. The FDML laser is ideal for swept-source OCT imaging, thus enabling high imaging speeds and large imaging depths.},
}