Dr. Christopher H. Betters Profile

Dr. Christopher H. Betters

Research Fellow at Univ of Sydney

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Author

Publications (25)

Proceedings Article | 18 December 2023 Paper

Aperiodic multi-notch FBG filters for astronomical positronium detection

Qingshan Yu, Liguo Luo, Göran Edvell, Christopher Betters, Jin Wei, Simon Ellis, Joss Bland-Hawthorn, Sergio Leon-Saval

Proceedings Volume 12965, 129650D (2023) https://doi.org/10.1117/12.3008044

KEYWORDS: Fiber Bragg gratings, Tunable filters, Design and modelling, Astronomy, Spectrographs, Bragg wavelengths, Optical filters, Modulation

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Proceedings Article | 6 October 2023 Presentation

Demonstration of linear and neural net closed-loop control with a photonic lantern focal-plane wavefront sensor

Jonathan Lin, Barnaby Norris, Olivier Guyon, Michael Fitzgerald, Yinzi Xin, Yoo Jung Kim, Sébastien Vievard, Julien Lozi, Sergio Leon-Saval, Christopher Betters, Steph Sallum, Pradip Gatkine, Dimitri Mawet, Nemanja Jovanovic

Proceedings Volume 12680, 126800L (2023) https://doi.org/10.1117/12.2677057

KEYWORDS: Wavefront sensors, Wavefront aberrations, Pupil aberrations, Adaptive optics, Neural networks, Equipment, Wavefront errors, Waveguides, Wavefront reconstruction, Telescopes

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Proceedings Article | 5 October 2023 Presentation + Paper

Photonic spectro-interferometry with SCExAO/FIRST at the Subaru Telescope: towards Hα imaging of protoplanets

S. Vievard, M. Lallement, E. Huby, S. Lacour, O. Guyon, N. Jovanovic, S. Leon-Saval, J. Lozi, V. Deo, K. Ahn, N. Cvetojevic, K. Barjot, G. Martin, H. D. Kenchington-Goldsmith, G. Duchêne, T. Kotani, F. Marchis, D. Rouan, M. Fitzgerald, S. Sallum, B. Norris, C. Betters, P. Gatkine, J. Lin, Y. J. Kim, C. Pham, C. Cassagnettes, A. Billat, M. Tamura, G. Perrin

Proceedings Volume 12680, 126800H (2023) https://doi.org/10.1117/12.2676319

KEYWORDS: Telescopes, Single mode fibers, Optical path differences, Spectrographs, Photonic integrated circuits, Polarization, Microelectromechanical systems, Calibration, Visible radiation

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Proceedings Article | 5 October 2023 Paper

Exploring the potential of coherent imaging using photonic lanterns with beam combiners

Yoo Jung Kim, Michael Fitzgerald, Jonathan Lin, Steph Sallum, Yinzi Xin, Nemanja Jovanovic, Sergio Leon-Saval, Christopher Betters, Pradip Gatkine, Olivier Guyon, Julien Lozi, Dimitri Mawet, Barnaby Norris, Sebastien Vievard

Proceedings Volume 12680, 126800K (2023) https://doi.org/10.1117/12.2677054

KEYWORDS: Visibility, Single mode fibers, Interferometry, Beam combiners, Telescopes, Image restoration, Stellar interferometry, Coherence imaging

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Proceedings Article | 5 October 2023 Presentation + Paper

The path to detecting extraterrestrial life with astrophotonics

Nemanja Jovanovic, Yinzi Xin, Michael Fitzgerald, Olivier Guyon, Peter Tuthill, Barnaby Norris, Pradip Gatkine, Greg Sercel, Svarun Soda, Yoo Jung Kim, Jonathan Lin, Sergio Leon-Saval, Rodrigo Amezcua-Correa, Stephanos Yerolatsitis, Julien Lozi, Sébastien Vievard, Chris Betters, Steph Sallum, Daniel Levinstein, Dimitri Mawet, Jeffrey Jewell, J. Kent Wallace, Nick Cvetojevic

Proceedings Volume 12680, 126800G (2023) https://doi.org/10.1117/12.2677951

KEYWORDS: Planets, Photonics, Stars, Exoplanets, Equipment, Astrophotonics, Wavefront sensors, Single mode fibers, Coronagraphy, Spectroscopy

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Proceedings Article | 30 August 2022 Presentation + Paper

Exoplanet detection with photonic lanterns for focal-plane wavefront sensing and control

Jonathan Lin, Yinzi Xin, Barnaby Norris, Yoo Jung Kim, Steph Sallum, Christopher Betters, Sergio Leon-Saval, Julien Lozi, Sebastian Vievard, Oliver Guyon, Pradip Gatkine, Nemanja Jovanovic, Dimitri Mawet, Michael Fitzgerald

Proceedings Volume 12185, 121852G (2022) https://doi.org/10.1117/12.2630692

KEYWORDS: Wavefront sensors, Wavefronts, Single mode fibers, Mathematical modeling, Telescopes, Photodetectors, Wavefront reconstruction, Wavefront aberrations, Monochromatic aberrations, Exoplanets

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Proceedings Article | 30 August 2022 Presentation + Paper

Demonstration of a photonic-lantern focal-plane wavefront sensor using fiber mode conversion and deep learning

Barnaby R. Norris, Jin Wei, Christopher Betters, Sergio Leon-Saval, Yinzi Xin, Jonathan Lin, Yoo Jung Kim, Steph Sallum, Julien Lozi, Sebastien Vievard, Olivier Guyon, Pradip Gatkine, Nemanja Jovanovic, Dimitri Mawet, Michael Fitzgerald

Proceedings Volume 12185, 1218530 (2022) https://doi.org/10.1117/12.2629852

KEYWORDS: Wavefronts, Wavefront sensors, Adaptive optics, Point spread functions, Photodetectors, Phase measurement, Multimode fibers, Telescopes, Fiber optics sensors, Astronomy

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Proceedings Article | 29 August 2022 Presentation + Paper

Experimental measurements of AO-fed photonic lantern coupling efficiencies

Jonathan Lin, Sebastian Vievard, Nemanja Jovanovic, Barnaby Norris, Michael P. Fitzgerald, Christopher Betters, Pradip Gatkine, Olivier Guyon, Yoo Jung Kim, Sergio Leon-Saval, Julien Lozi, Dimitri Mawet, Steph Sallum, Yinzi Xin

Proceedings Volume 12188, 121882E (2022) https://doi.org/10.1117/12.2630608

KEYWORDS: Single mode fibers, Point spread functions, Telescopes, Power meters, Physics, Device simulation, Spectrographs, Near infrared, Turbulence, Sensors

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Proceedings Article | 29 August 2022 Poster + Paper

Spectroastrometry with photonic lanterns

Yoo Jung Kim, Stephanie Sallum, Jonathan Lin, Yinzi Xin, Barnaby Norris, Christopher Betters, Sergio Leon-Saval, Julien Lozi, Sebastian Vievard, Pradip Gatkine, Olivier Guyon, Nemanja Jovanovic, Dimitri Mawet, Michael Fitzgerald

Proceedings Volume 12184, 1218449 (2022) https://doi.org/10.1117/12.2630635

KEYWORDS: Binary data, Single mode fibers, Planets, Monochromatic aberrations, Wavefronts, Telescopes, Spectroscopy, Photodetectors, Photonics, Astronomical spectroscopy, Astronomical detectors, Waveguides

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SPIE Journal Paper | 29 June 2021

Learning the lantern: neural network applications to broadband photonic lantern modeling

David Sweeney, Barnaby R. Norris, Peter Tuthill, Richard Scalzo, Jin Wei, Christopher Betters, Sergio Leon-Saval

JATIS, Vol. 7, Issue 02, 028007, (June 2021) https://doi.org/10.1117/12.10.1117/1.JATIS.7.2.028007

KEYWORDS: Waveguides, Data modeling, Wavefronts, Neural networks, Lithium, Zernike polynomials, Broadband telecommunications, Single mode fibers, Beam propagation method, Telescopes

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Proceedings Article | 11 June 2021 Open Access

CUAVA InGaAs-based, Short Wavelength InfraRed (SWIR) instrument for atmospheric reconnaissance: preliminary design

Naif Alsalem, Christopher Betters, Sergio Leon-Saval, Iver Cairns

Proceedings Volume 11852, 118526A (2021) https://doi.org/10.1117/12.2600239

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Proceedings Article | 13 December 2020 Presentation + Paper

An innovative integral field unit upgrade with 3D-printed micro-lenses for the RHEA at Subaru

Theodoros Anagnos, Pascal Maier, Philipp Hottinger, Christopher Betters, Tobias Feger, Sergio Leon-Saval, Itandehui Gris-Sánchez, Stephanos Yerolatsitis, Julien Lozi, Tim Birks, Sébastien Vievard, Nemanja Jovanovic, Adam Rains, Michael Ireland, Robert Harris, Blaise Kuo Tiong, Olivier Guyon, Barnaby Norris, Sebastiaan Haffert, Matthias Blaicher, Yulin Xu, Moritz Straub, Jörg-Uwe Pott, Oliver Sawodny, Philip Neureuther, David Coutts, Christian Schwab, Christian Koos, Andreas Quirrenbach

Proceedings Volume 11451, 114516Y (2020) https://doi.org/10.1117/12.2560626

KEYWORDS: Spectrographs, Adaptive optics, Free space optics, Large telescopes, Optical instrument design, Diffraction, Spectral resolution, Free space, Lenses, Exoplanets

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Proceedings Article | 13 December 2020 Presentation

The TOLIMAN space telescope: discovering exoplanets in the solar neighbourhood

Peter Tuthill, Louis Desdoigts, Christopher Betters, Barnaby Norris, Iver Cairns, Sergio Leon-Saval

Proceedings Volume 11446, 1144612 (2020) https://doi.org/10.1117/12.2563081

KEYWORDS: Space telescopes, Environmental sensing, Target detection, Telescopes, Eye

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Proceedings Article | 2 March 2020 Presentation + Paper

Measurements of few-mode fiber photonic lanterns in emulated atmospheric conditions for a low earth orbit space to ground optical communication receiver application

Sarah Tedder, Bertram Floyd, Yousef Chahine, Benjamin Croop, Brian Vyhnalek, Christopher Betters, Sergio Leon-Saval

Proceedings Volume 11272, 112720U (2020) https://doi.org/10.1117/12.2542848

KEYWORDS: Single mode fibers, Atmospheric propagation, Sensors, Receivers, Turbulence, Atmospheric modeling, Atmospheric optics, Telescopes, Earth's atmosphere

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Proceedings Article | 4 March 2019 Presentation + Paper

Single-mode fiber and few-mode fiber photonic lanterns performance evaluated for use in a scalable real-time photon counting ground receiver

Sarah Tedder, Brian Vyhnalek, Sergio Leon-Saval, Christopher Betters, Bert Floyd, Jeremy Staffa, Robert Lafon

Proceedings Volume 10910, 109100G (2019) https://doi.org/10.1117/12.2507478

KEYWORDS: Single mode fibers, Receivers, Sensors, Telescopes, Digital micromirror devices, Fiber couplers, Spatial light modulators, Dispersion, Photon counting, Commercial off the shelf technology, Free space optical communications

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Photonic lanterns provide an efficient way of coupling light from a single large-core fiber to multiple small-core fibers. This capability is of interest for space to ground communication applications. In these applications, the optical ground receivers require high-efficiency coupling from an atmospherically distorted focus spot to multiple fiber coupled single pixel super-conducting nanowire detectors. This paper will explore the use of photonic lanterns in a real-time ground receiver that is scalable and constructed with commercial parts. The number of small-core fibers (i.e. an array of single or few-mode cores) that make a photonic lantern determines the number of spatial modes that they couple at the larger multimode fiber core end. For instance, lanterns made with n number of single-mode fibers can couple n number of spatial modes. Although the laser transmitted from a spacecraft originates as a Gaussian shape, the atmosphere distorts the beam profile by scrambling the phase and scattering energy into higher-order spatial modes. Therefore, if a ground receiver is sized for a target data rate with n number of detectors, the corresponding lantern made with single-mode fibers will couple n number of spatial modes. Most of the energy of the transmitted beam scattered into spatial modes higher than n will be lost. This paper shows this loss may be reduced by making lanterns with few-mode fibers instead of single-mode fibers, increasing the number of spatial modes that can be coupled and therefore increasing the coupling efficiency to single pixel, single photon detectors. The free space to fiber coupling efficiency of these two types of photonic lanterns are compared over a range of the free-space coupling numerical apertures and mode field diameters. Results indicate the few mode fiber lantern has higher coupling efficiency for telescopes with longer focal lengths under higher turbulent conditions. Also presented is analysis of the jitter added to the system by the lanterns, showing the few-mode fiber photonic lantern adds more jitter than the single-mode fiber lantern, but less than a multimode fiber.

Proceedings Article | 4 August 2016 Paper

Precision radial velocities with inexpensive compact spectrographs

Christopher Betters, Alex Murray, Joss Bland-Hawthorn, Sergio Leon-Saval

Proceedings Volume 9908, 99081B (2016) https://doi.org/10.1117/12.2232126

KEYWORDS: Spectrographs, Calibration, Spectral resolution, Single mode fibers, Astronomy, Visible radiation, Sensors, Charge-coupled devices, Diffraction, Telescopes

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Proceedings Article | 3 August 2016 Paper

Efficiently feeding single-mode fiber photonic spectrographs with an extreme adaptive optics system: on-sky characterization and preliminary spectroscopy

N. Jovanovic, N. Cvetojevic, C. Schwab, B. Norris, J. Lozi, S. Gross, C. Betters, G. Singh, O. Guyon, F. Martinache, D. Doughty, P. Tuthill

Proceedings Volume 9908, 99080R (2016) https://doi.org/10.1117/12.2234299

KEYWORDS: Spectrographs, Adaptive optics, Single mode fibers, Apodization, Wavefronts, Telescopes, Calibration, Cameras, Point spread functions, Imaging spectroscopy

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Proceedings Article | 22 July 2016 Paper

Low cost photonic comb for sub-m/s wavelength calibration

Christopher Betters, Maxime Hermouet, Thomas Blanc, James Colless, Joss Bland-Hawthorn, Janez Kos, Sergio Leon-Saval

Proceedings Volume 9912, 99126Y (2016) https://doi.org/10.1117/12.2233678

KEYWORDS: Fabry–Perot interferometers, Rubidium, Calibration, Spectrographs, Single mode fibers, Velocity measurements, Optical fibers, Switches, Lamps, Absorption

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Proceedings Article | 28 July 2014 Paper

The problem of scattering in fibre-fed VPH spectrographs and possible solutions

S. Ellis, Will Saunders, Chris Betters, Scott Croom

Proceedings Volume 9151, 91511V (2014) https://doi.org/10.1117/12.2057108

KEYWORDS: Scattering, Point spread functions, Spectrographs, Light scattering, Telescopes, Fourier transforms, Fiber Bragg gratings, Surface roughness, Electroluminescent displays, Apodization

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Proceedings Article | 8 July 2014 Paper

PIMMS échelle: the next generation of compact diffraction limited spectrographs for arbitrary input beams

Christopher Betters, Sergio Leon-Saval, Joss Bland-Hawthorn, Samuel Richards, Tim Birks, Itandehui Gris-Sánchez

Proceedings Volume 9147, 91471I (2014) https://doi.org/10.1117/12.2055638

KEYWORDS: Spectrographs, Spectral resolution, Sensors, Photonics, Telescopes, Visible radiation, Cameras, Astrophotonics, Optical simulations, Optical design

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Proceedings Article | 24 September 2012 Paper

Demonstration and design of a compact diffraction limited spectrograph

Christopher Betters, Sergio Leon-Saval, Joss Bland-Hawthorn, Gordon Robertson

Proceedings Volume 8446, 84463H (2012) https://doi.org/10.1117/12.925824

KEYWORDS: Spectrographs, Spectral resolution, Collimators, Sensors, Single mode fibers, Cameras, Gaussian beams, Photonics, Point spread functions, Optical simulations

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Proceedings Article | 21 September 2012 Paper

NanoSpec: a diffraction limited micro-spectrograph for pico- and nano-satellites

Christopher Betters, S. Leon-Saval, J. Bland-Hawthorn

Proceedings Volume 8442, 84424B (2012) https://doi.org/10.1117/12.925819

KEYWORDS: Spectrographs, Satellites, Sensors, Particles, Charged particle optics, Single mode fibers, Spectral resolution, Diffraction, Collimators, Refractive index

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Proceedings Article | 21 September 2012 Paper

The i-INSPIRE satellite: a university pico-satellite project

Lisa Fogarty, Size Xiao, Jiro Funamoto, Iver Cairns, Joss Bland-Hawthorn, Xiaofeng Wu, Christopher Betters, Sergio Leon-Saval, Anthony Monger

Proceedings Volume 8442, 84421B (2012) https://doi.org/10.1117/12.925709

KEYWORDS: Satellites, Cameras, Space operations, Satellite communications, Photography, Spectrographs, Aerospace engineering, Satellite imaging, Data communications, Transceivers

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Proceedings Article | 13 September 2012 Paper

The Photonic TIGER: a multicore fiber-fed spectrograph

Sergio Leon-Saval, Christopher Betters, Joss Bland-Hawthorn

Proceedings Volume 8450, 84501K (2012) https://doi.org/10.1117/12.925254

KEYWORDS: Spectrographs, Sensors, Diffraction, Single mode fibers, Telescopes, Dispersion, Astronomy, Adaptive optics, Laser sources, Iterated function systems

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Proceedings Article | 15 July 2010 Paper

PIMMS: photonic integrated multimode microspectrograph

Joss Bland-Hawthorn, Jon Lawrence, Gordon Robertson, Sam Campbell, Ben Pope, Chris Betters, Sergio Leon-Saval, Tim Birks, Roger Haynes, Nick Cvetojevic, Nem Jovanovic

Proceedings Volume 7735, 77350N (2010) https://doi.org/10.1117/12.856347

KEYWORDS: Spectrographs, Waveguides, Single mode fibers, Sensors, Telescopes, Spectroscopes, Electrons, Photonic devices, Diffraction, Spectral resolution

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Showing 5 of 25 publications

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