Dr. David J. M. Stothard Profile

Dr. David J. M. Stothard

Head of Lasers and Laser Systems at Fraunhofer Ctr for Applied Photonics

SPIE Involvement:

Author

Publications (17)

Proceedings Article | 8 March 2023 Presentation + Paper

Highly-compact and power-scalable transition-metal-doped single-frequency lasers

Alexander Lagatsky, Gerald Bonner, Peter Schlosser, David J. Stothard, Loyd McKnight

Proceedings Volume 12399, 123990G (2023) https://doi.org/10.1117/12.2645876

KEYWORDS: Semiconductor lasers, Alexandrite lasers, Laser resonators, Output couplers, Laser crystals, Crystals, Laser frequency, Quantum systems, Laser systems engineering, Sapphire lasers

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Proceedings Article | 30 May 2022 Presentation + Paper

Stand-off explosive sensing and imaging with scanning dual-comb spectrometer

John Macarthur, Jakob Hayden, Matthew Warden, Christopher Carson, David Stothard, Raphael Horvath, Florian Eigenmann, Markus Geiser, Vasili Savitski

Proceedings Volume 12116, 1211604 (2022) https://doi.org/10.1117/12.2616668

KEYWORDS: Scanning, Spectroscopy, Absorption, FT-IR spectroscopy, Explosives, Backscatter, Reflection

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Proceedings Article | 30 May 2022 Presentation

Long-range, range-resolved detection of H2 using single-photon ‘quantum’ Raman: a condition monitoring tool for long-term storage of nuclear materials

David J. Stothard, Matthew Warden, Roman Spesyvtsev, Ellis Kelly, John Leck, Alexander Allen, Jon Squire, Stephen Hepworth, Simon Malone, Jo Tunney, Frank Allison, David Armstrong, David Li, Loyd McKnight

Proceedings Volume PC12116, PC1211608 (2022) https://doi.org/10.1117/12.2621423

KEYWORDS: Hydrogen, Single photon detectors, Raman spectroscopy, Absorption, Ultraviolet radiation, Sensors, Packaging, Laser applications, Inspection, Hydrogen production

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Proceedings Article | 30 May 2022 Presentation

Combined deep-UV induced fluorescence multispectral imaging and resonance-Raman: a dual modality approach for rapid location and identification of in-theatre biological contaminants

David J. Stothard, John Leck, Marek Michalowski, Paul Murray, Stephen Marshall, Kelly Curtis, Chris Howle, William Brooks, Michael Foster

Proceedings Volume PC12116, PC1211609 (2022) https://doi.org/10.1117/12.2621607

KEYWORDS: Raman spectroscopy, Luminescence, Deep ultraviolet, Multispectral imaging, Contamination, Spectroscopy, Spatial resolution, Sensors, Scene classification, Heterodyning

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Proceedings Article | 30 May 2022 Presentation

GaN laser diodes for quantum sensing, optical atomic clocks, and quantum computing

Stephen Najda, Piotr Perlin, Tadek Suski, Szymon Stanczyk, Mike Leszczynski, Dario Schiavon, Thomas Slight, Steffan Gwyn, Scott Watson, Anthony Kelly, Martin Knapp, Mohsin Haji, David J. Stothard

Proceedings Volume PC12093, PC1209302 (2022) https://doi.org/10.1117/12.2612039

KEYWORDS: Quantum computing, Semiconductor lasers, Gallium nitride, Atomic clocks, Quantum optics, Optical sensing, Strontium, Sensors, Quantum clocks, Laser systems engineering

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Proceedings Article | 12 April 2021 Presentation + Paper

Routes to enabling Raman detection of in-theatre biological contaminants over extended range: spatial heterodyne spectroscopy, time-resolved Raman measurements, and the march towards the deep-UV

David J. Stothard, Matthew Warden, Michael Foster, William Brooks

Proceedings Volume 11749, 117490B (2021) https://doi.org/10.1117/12.2590277

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Proceedings Article | 17 May 2019 Paper

Quantum cascade laser-based trace detection of gases in the deep-infrared region using phase fluctuation optical heterodyne spectroscopy

Jack Thomas, Adam Polak, David J. Stothard

Proceedings Volume 11010, 1101014 (2019) https://doi.org/10.1117/12.2521038

KEYWORDS: Quantum cascade lasers, Absorption, Spectroscopy, Laser spectroscopy, Heterodyning, Optical spectroscopy, Gases, Interferometers, Tunable lasers, Infrared detectors

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Proceedings Article | 29 May 2018 Paper

Towards a compact, portable, handheld device for contactless real-time standoff detection of hazardous substances

Christopher Carson, John Macarthur, Matthew Warden, David Stothard, Lorenz Butschek, Stefan Hugger, Jan-Philip Jarvis, Marko Haertelt, Ralf Ostendorf, Andre Merten, Markus Schwarzenberg, Jan Grahmann, Marcin Ratajczyk

Proceedings Volume 10624, 106240F (2018) https://doi.org/10.1117/12.2305711

KEYWORDS: Sensors, Microopto electromechanical systems, Quantum cascade lasers, Standoff detection, Mid-IR, Explosives

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Proceedings Article | 16 May 2018 Presentation + Paper

Optical parametric oscillator-based trace detection of gases in the mid-infrared region using phase-fluctuation optical heterodyne spectroscopy

Jack Thomas, Adam Polak, Gerald Bonner, Sandra Enderle, Malcolm Dunn, David J. M. Stothard

Proceedings Volume 10629, 106290V (2018) https://doi.org/10.1117/12.2305736

KEYWORDS: Absorption, Modulation, Interferometers, Mid-IR, Gases, Spectroscopy, Sensors, Optical parametric oscillators, Temperature metrology, Interference (communication)

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Proceedings Article | 16 May 2018 Paper

Enhanced photoacoustic spectroscopy sensitivity through intra-cavity OPO excitation

Adam Polak, David J. Stothard

Proceedings Volume 10629, 106291D (2018) https://doi.org/10.1117/12.2305737

KEYWORDS: Optical parametric oscillators, Photoacoustic spectroscopy, Absorption, Diodes, Explosives detection, Explosives, Crystals, Semiconductor lasers

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SPIE Journal Paper | 12 September 2017 Open Access

Microoptoelectromechanical systems-based external cavity quantum cascade lasers for real-time spectroscopy

Lorenz Butschek, Stefan Hugger, Jan Jarvis, Marko Haertelt, André Merten, Markus Schwarzenberg, Jan Grahmann, David Stothard, Matthew Warden, Christopher Carson, John Macarthur, Frank Fuchs, Ralf Ostendorf, Joachim Wagner

OE, Vol. 57, Issue 01, 011010, (September 2017) https://doi.org/10.1117/12.10.1117/1.OE.57.1.011010

KEYWORDS: Microopto electromechanical systems, Quantum cascade lasers, Spectroscopy, Scanners, Coating, Laser sources, Silicon, Mid-IR, FT-IR spectroscopy, Sensors

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Proceedings Article | 16 February 2017 Presentation + Paper

AlGaInN laser-diode technology for optical clocks and atom interferometry

S. Najda, P. Perlin, T. Suski, L. Marona, S. Stanczyk, M. Leszczyński, P. Wisniewski, R. Czernecki, G. Targowski, C. Carson, D. Stothard, L. McKnight

Proceedings Volume 10104, 101041L (2017) https://doi.org/10.1117/12.2250322

KEYWORDS: Optical clocks, Chemical species, Interferometry, Semiconductor lasers, Laser applications, Gallium nitride, Gallium, Indium, Quantum wells, Laser development

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Proceedings Article | 30 October 2012 Paper

Stand-off spectroscopy for the detection of chemical warfare agents

Rhea Clewes, Chris Howle, David J. Stothard, Malcolm Dunn, Gordon Robertson, William Miller, Graeme Malcolm, Gareth Maker, Rick Cox, Brad Williams, Matt Russell

Proceedings Volume 8546, 85460X (2012) https://doi.org/10.1117/12.974574

KEYWORDS: Raman spectroscopy, Photons, Imaging systems, Sensors, Spectroscopy, Liquids, Blistering agents, Optical parametric oscillators, Crystals

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The most desirable configuration for detection of toxic chemicals utilises the maximum distance between detector and hazard. This approach minimises the contamination of equipment or personnel. Where the target chemical is an involatile liquid, indirect detection of the liquid contamination is made difficult by inherently low vapour pressure. In this instance, direct detection of the chemical hazard is the best approach. Recent technology developments have allowed spectroscopic systems to provide multiple options for the stand-off detection of involatile chemical warfare agents (CWAs). Two different stand-off spectroscopic systems, based upon IR absorption and Raman spectroscopic techniques are described here. The Negative Contrast Imager (NCI) is based upon an optical parametric oscillator (OPO) source comprising a Q-switched intracavity MgO:PPLN crystal. This crystal has a fanned grating design and wavelength tuning is achieved by translating the PPLN crystal within the 1064 nm pump beam. This approach enables the production of shortwave and midwave IR radiation (1.5 – 1.8 μm and 2.6 – 3.8 μm, respectively), which is scanned across the scene of interest. Target materials that have an absorption feature commensurate with the wavelength of incoming radiation reduce the intensity of returned signal, resulting in dark pixels in the acquired image. This method enables location and classification of the target material. Stand-off Raman spectroscopy allows target chemicals to be identified at range through comparison of the acquired signature relative to a spectral database. In this work, we used a Raman system based upon a 1047 nm Nd:YLF laser source and a proprietary InGaAsP camera system. Utilisation of a longer excitation wavelength than most conventional stand-off detection systems (e.g. 532 or 785 nm) enables reduction of fluorescence from both the surface and the deposited chemicals, thereby revealing the Raman spectrum. NCI and Raman spectroscopy are able to detect CWAs on surfaces at distances of 2 – 10 metres and have potential to detect over longer ranges. We report the successful identification of at least 60 μl of nitrogen mustard at a distance of a 2 m and 10 m using NCI and Raman spectroscopy.

Proceedings Article | 6 October 2011 Paper

Hazardous liquid detection by active hyperspectral imaging

Chris Howle, Alexander Frisby, Alastair J. McIntosh, David J. Stothard, Malcolm Dunn, Gordon Robertson, William Miller, Graeme Malcolm, Gareth Maker

Proceedings Volume 8189, 81890H (2011) https://doi.org/10.1117/12.898516

KEYWORDS: Mid-IR, Optical parametric oscillators, Mirrors, Crystals, Absorption, Liquids, Hyperspectral imaging, Short wave infrared radiation, Laser crystals, Sensors

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Proceedings Article | 9 October 2009 Paper

Active infrared hyperspectral imaging system using a broadly tunable optical parametric oscillator

G. P. Malcolm, G. Maker, G. Robertson, M. Dunn, D. J. Stothard

Proceedings Volume 7486, 74860H (2009) https://doi.org/10.1117/12.833602

KEYWORDS: Optical parametric oscillators, Absorption, Mirrors, Imaging systems, Hyperspectral imaging, Nonlinear crystals, Infrared imaging, Liquids, Mid-IR, Gases

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