Dr. Kevin Barjot Profile

Dr. Kevin Barjot

at Observatoire de Paris

SPIE Involvement:

Author

Area of Expertise:

Interferometry , optics , photonics , exoplanets

Publications (19)

Proceedings Article | 28 August 2024 Poster + Paper

Poster + Paper

CHARA Array integrated optics testbench (CHARIOT) for on-sky experiments

Alyssa Mayer, Aline Dinkelaker, Kalaga Madhav, Lucas Labadie, Kévin Barjot, Nicholas Scott, Narsireddy Anugu, Aurélien Benoît, Robert Thomson, Robert Harris, Christopher Farrington, Rainer Koehler, Karolina Kubiak, Edgar Ligon, Gail Schaefer

Proceedings Volume 13095, 130951V (2024) https://doi.org/10.1117/12.3019140

KEYWORDS: Beam combiners, Mirrors, Integrated optics, K band, Optical path differences, Nulling interferometry, Telescopes, Equipment, Astrophotonics, Astronomical interferometry, Near infrared, Astronomical instrumentation engineering, Astronomical instrumentation, Femtosecond laser micromachining, Optical benches

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Proceedings Article | 28 August 2024 Poster + Paper

Poster + Paper

A new photonic integrated circuit for the FIRST instrument: towards high throughput with a compact photonic chip

Harry-Dean Kenchington Goldsmith, Elsa Huby, Manon Lallement, Kévin Barjot, Sebastien Vievard, Vincent Deo, Olivier Guyon, Guillermo Martin, Sylvestre Lacour

Proceedings Volume 13095, 130951Z (2024) https://doi.org/10.1117/12.3018270

KEYWORDS: Waveguides, Photonic integrated circuits, Fabrication, Design, Telescopes, Scattered light, Polarization, Directional couplers

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A photonic integrated circuit (PIC) is a lightweight, compact alternative to bulk optics. The Fibered Imager foR a Single Telescope (FIRST) instrument, is a spectro-interferometer performing pupil remapping and designed to operate in the 600 to 800nm visible wavelength range. It is installed on the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument’s platform at the Subaru telescope. In the integrated optical version of FIRST (FIRST PIC), the interferometric combination of the beams occurs by the pairwise combination of five sub-apertures to achieve 20 baselines. This paper introduces a PIC design with novel components for splitting and pairwise coupling the light for FIRST PIC, fabricated and packaged by LioniX International. A high index difference between the waveguide fundamental mode and cladding material was selected to allow compact circuits with prospects of increasing the number of combined sub-apertures with designs of much greater complexity. The high confinement waveguides were simulated to produce approximately 50% injection loss, a tapering system in both height and width to a low confinement waveguide at the PIC interface ameliorated the loss. The optimised throughput prediction is estimated at 80%. Standard couplers and splitters are expected to have high losses due to fabrication tolerances, and due to the high confinement, standard couplers’ performance is highly dependent on the wavelength. Presented here are novel component designs to replace them. Tapered directional couplers, which maintain an acceptable coupling ratio over the entire bandwidth, and tri-couplers, with higher throughput than conventional splitters but high intolerance to fabrication issues, were designed and fabricated for this purpose. The designs and individual experimental verification will be discussed, focusing on polarization and wavelength response. The full combination of components was used to create a five sub-aperture combiner for FIRST. Cross-talk between crossed waveguides was measured independently for the two polarisations. The cross-coupling over the full bandwidth was measured as low as 2% in one polarization, without active subtraction for scattered light to confirm the light in the ports was guided from the cross-coupling, and as low as 8% in the other. Additional work, and potential refinement of the photonic chip components, are required to differentiate the scattered light from the cross-talk to ensure it is reduced in both polarisations.

Proceedings Article | 28 August 2024 Presentation

Presentation

Status of FIRST spectro-interferometer on SCExAO: sensitivity study and characterization of 5-telescopes visible photonics integrated circuits

Manon Lallement, Elsa Huby, Sylvestre Lacour, Sebastien Vievard, Guillermo Martin, Harry-Dean Kenchington Goldsmith, Kévin Barjot, Olivier Guyon, Julien Lozi, Vincent Deo, Kyohoon Ahn, Miles Lucas, Cécil Pham, Cédric Cassagnettes, Daniel Rouan, Vincent Lapeyrere, Guy Perrin, Nick Cvetojevic, Frantz Martinache, Franck Marchis, Takayuki Kotani, Gaspard Duchene

Proceedings Volume 13095, 1309508 (2024) https://doi.org/10.1117/12.3018406

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Proceedings Article | 26 August 2024 Poster + Paper

Poster + Paper

FIRST 5T 3D: interferometric performances of a laser written bream combiner for FIRST/SUBARU

G. Martin, K. Barjot, M. Lallement, H. Kenchington-Smith, E. Huby, S. Lacour, C. d'Amico, R. Stoian, S. Vievard, O. Guyon, V. Deo, G. Zhang, G. Cheng

Proceedings Volume 13100, 131007C (2024) https://doi.org/10.1117/12.3019221

KEYWORDS: Waveguides, Microelectromechanical systems, Beam combiners, Binary stars, Photonic integrated circuits, Laser interferometry, Crosstalk, Telescopes, Laser optics, Equipment

Read Abstract +

FIRST (Fibered Imager foR a Single Telescope instrument) is an on-sky instrument at SUBARU Telescope that enables high-contrast imaging and spectroscopy, thanks to a unique combination of pairwise combination of sub-apertures using a Photonic Integrated Circuit that allows spatial filtering by single-mode waveguides and cross-dispersion in the visible (~ 600-800 nm), a high-efficiency alternative to sparse aperture masking. To reduce crosstalk observed in planar PICs, and therefore increase the instrument’s stability and sensitivity, we have designed and fabricated a series of 3D laserwritten optical PICs with 5T beam combiners. Different laser powers were used to address different single-mode spectral ranges. The multi-aperture beam combiner consists of five input waveguides spaced by 250 μm. Each input is split into four waveguides and the twenty channels undergo pairwise recombination, using Y-junctions, to produce ten outputs. In this work, we present the interferometric performances of these 3D PICs when exposed to a point-like light source (single star) or a two-points-like light source (binary) on the FIRST/SUBARU instrument replica built at LESIA – Observatoire de Paris.

In previous work, we identified the optimal 5T 3D device, as being single-mode between 550-800 nm and showing good internal transmission in all input channels, above 45% at 635nm. The internal transmission (sum of the output values obtained for the four waveguides of the 1x4 splitter as normalized to the output signal obtained from the straight waveguide used as a reference) was measured. Two inputs achieved 80% transmission. The PIC was installed in the FIRST/SUBARU optical bench simulator at LESIA, to inject light into five inputs simultaneously and scan the fringes using independent MEMS segments, inducing a relative OPD modulation. The results of this study, comparing the signature obtained for a single source (star) as compared to a binary, will be presented in this work. We will show that both polarizations are guided, with no crosstalk, and analyze the interferometric performances as a function of the source type, showing that the binary companion can be detected.

Proceedings Article | 19 July 2024 Presentation

Presentation

Spectroscopy below the diffraction limit with FIRST at the Subaru Telescope

Elsa Huby, Sébastien Vievard, Gaspard Duchene, Olivier Guyon, Sylvestre Lacour, Guy Perrin, Kevin Barjot, Vincent Deo, Nemanja Jovanovic, Harry-Dean Kenchington Goldsmith, Takayuki Kotani, Manon Lallement, Vincent Lapeyrere, Julien Lozi, Franck Marchis, Guillermo Martin, Daniel Rouan

Proceedings Volume 13096, 130960O (2024) https://doi.org/10.1117/12.3019806

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Proceedings Article | 5 October 2023 Presentation + Paper

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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SPIE Journal Paper | 18 April 2023

Photonic beam-combiner for visible interferometry with Subaru coronagraphic extreme adaptive optics/fibered imager for a single telescope: laboratory characterization and design optimization

Manon Lallement, Elsa Huby, Sylvestre Lacour, Guillermo Martin, Kevin Barjot, Guy Perrin, Daniel Rouan, Vincent Lapeyrere, Sebastien Vievard, Olivier Guyon, Julien Lozi, Vincent Deo, Takayuki Kotani, Cecil Pham, Cedric Cassagnettes, Adrien Billat, Nick Cvetojevic, Franck Marchis

JATIS, Vol. 9, Issue 02, 025003, (April 2023) https://doi.org/10.1117/12.10.1117/1.JATIS.9.2.025003

KEYWORDS: Waveguides, Photonic integrated circuits, Directional couplers, Design and modelling, Phase shifts, Interferometry, Beam combiners, Coronagraphy, Telescopes, Polarization

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Proceedings Article | 30 August 2022 Poster + Paper

Poster + Paper

Connecting the astronomical testbed community - the CAOTIC project: optimized teaching methods for software version control concepts

Iva Laginja, Pablo Robles, Kevin Barjot, Lucie Leboulleux, Rebecca Jensen-Clem, Keira Brooks, Christopher Moriarty

Proceedings Volume 12185, 121853A (2022) https://doi.org/10.1117/12.2629483

KEYWORDS: Astronomy, Software development, Adaptive optics, Computer programming, Astronomical instrumentation, Control systems, Computer programming languages, Wavefront sensors, Software engineering, Imaging systems

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Proceedings Article | 29 August 2022 Poster + Paper

Poster + Paper

Hybrid electro-optic visible multi-telescope beam combiner for next generation FIRST/SUBARU instruments

G. Martin, M. Foin, S. Phatak, M. Beldjoudi, A. Billat, C. Cassagnettes, A. Coste, N. Courjal, M. Lallement, K. Barjot, N. Cvetojevic, S. Vievard, E. Huby, S. Lacour, V. Deo, O. Guyon

Proceedings Volume 12188, 121885Y (2022) https://doi.org/10.1117/12.2630039

KEYWORDS: Modulation, Polarization, Electro optics, Waveguides, Lithium niobate, Phase modulation, Beam splitters, Glasses, Crystals, Telescopes

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Proceedings Article | 29 August 2022 Poster + Paper

Poster + Paper

FIRST 5T 3D: a laser written device for FIRST/SUBARU reducing crosstalk and propagation losses

G. Martin, A. Morand, C. d'Amico, R. Stoian, K. Barjot, M. Lallement, N. Cvetojevic, S. Vievard, E. Huby, S. Lacour, V. Deo, O. Guyon, J. Lv, G. Zhang, G. Cheng

Proceedings Volume 12188, 121882T (2022) https://doi.org/10.1117/12.2630010

KEYWORDS: Waveguides, Telescopes, Microelectromechanical systems, Laser optics, Interferometry, Modulation, Wave propagation, Visible radiation, Polarization, Optical simulations

Read Abstract +

FIRST (Fibered Imager foR a Single Telescope instrument) is an instrument that enables high contrast imaging and spectroscopy, thanks to a unique combination of sparse aperture masking, spatial filtering by single-mode waveguides and cross-dispersion in the visible. In order to increase the instrument’s stability and sensitivity, we have designed and fabricated a 3D laser-written optical chip 5T beam combiner. The multi-aperture beam combiner consists of 5 input waveguides spaced by 250um. Each input is split into 4 waveguides. A pairwise recombination scheme with Yjunctions produces/leads to 10 outputs (127um separation, compatible with commercial V-grooves). In this work, we present the experimental characterization of the chip: transmission performance, polarization issues and single mode spectral range. The targeted single mode spectral range must cover 550-800nm. Different optical powers for laser writing are used to finely tune the ideal single-mode behavior of the waveguides, ranging from 220 to 270mW. A straight waveguide was used as a reference, imprinted close to the first interferometric channel. Using different lasers (635nm, 780nm and 980nm) as well as wideband sources, we have been able to characterize the spectral transmission, the polarization behavior (TE/TM) and the interferometric contrast. The chip was inserted in the FIRST/SUBARU optical bench simulator at LESIA, in order to inject the 5 inputs simultaneously and scan the fringes using 4 independent MEMS, inducing a relative OPD modulation. Preliminary results show very good transmission for such a complex chip: all input channels are above 45% at 635nm (comparing the injected single mode with the sum of the 4 corresponding outputs), with two inputs reaching 80%. A huge advantage of this technology is to avoid the crosstalk due to in-plane waveguide crossings, and we show that no crosstalk is indeed observed. Both polarizations are transmitted, without noticeable birefringence. However, perfect vertical alignment of the outputs is difficult to obtain, and must be optimized prior to any connectorization to fiber bundles.

Proceedings Article | 29 August 2022 Presentation + Paper

Presentation + Paper

Photonic chip for visible interferometry: laboratory characterization and comparison with the theoretical model

Manon Lallement, Sylvestre Lacour, Elsa Huby, Guillermo Martin, Kevin Barjot, Guy Perrin, Daniel Rouan, Vincent Lapeyrere, Sébastien Vievard, Olivier Guyon, Julien Lozi, Vincent Deo, Takayuki Kotani, Cecil Pham, Cedric Cassagnettes, Adrien Billat, Nick Cvetojevic, Franck Marchis

Proceedings Volume 12188, 121882F (2022) https://doi.org/10.1117/12.2629449

KEYWORDS: Waveguides, Directional couplers, Photonic integrated circuits, Polarization, Phase shifts, Telescopes, Interferometry, Optical simulations, Single mode fibers

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Proceedings Article | 29 August 2022 Presentation

Presentation

Interferometric wavefront sensing at FIRST/SCExAO : self-calibrated fibered pupil-remapping spectrocopy using a metrology laser source

Sébastien Vievard, Vincent Deo, Elsa Huby, Sylvestre Lacour, Olivier Guyon, Nick Cvetojevic, Kevin Barjot, Guillermo Martin, Manon Lallement, Julien Lozi, Takayuki Kotani, Franck Marchis, Daniel Rouan, Kyohoon Ahn, Nour Skaf, Guy Perrin

Proceedings Volume 12183, 121830R (2022) https://doi.org/10.1117/12.2629299

KEYWORDS: Interferometry, Wavefront sensors, Telescopes, Metrology, Laser sources, Calibration, Spatial resolution, Optical fibers, Imaging systems, Coronagraphy

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Proceedings Article | 29 August 2022 Presentation

Presentation

First light of the upgraded FIRST visible fibered interferometer at the Subaru telescope (thesis)

Kevin Barjot, Elsa Huby, Sébastien Vievard, Manon Lallement, Sylvestre Lacour, Guillermo Martin, Nick Cvetojevic, Vincent Deo, Olivier Guyon, Julien Lozi, Takayuki Kotani, Cédric Cassagnettes, Adrien Billat, Franck Marchis, , Vincent Lapeyrère, Daniel Rouan

Proceedings Volume 12183, 121830E (2022) https://doi.org/10.1117/12.2630259

KEYWORDS: Telescopes, Visible radiation, Interferometers, Imaging spectroscopy, Stars, Waveguides, Visibility, Spectroscopy, Spectral resolution, Spatial resolution

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Proceedings Article | 1 September 2021 Presentation + Paper

Presentation + Paper

Very high resolution spectro-interferometry with wavefront sensing capabilities on Subaru/SCExAO using photonics

S. Vievard, K. Ahn, A. Arriola, K. Barjot, N. Cvetojevic, V. Deo, T. Gretzinger, S. Gross, O. Guyon, E. Huby, N. Jovanovic, T. Kotani, S. Lacour, T. Lagadec, M. Lallement, V. Lapeyrere, J. Lozi, F. Marchis, G. Martin, M.-A. Martinod, B. Norris, G. Perrin, D. Rouan, N. Skaf, P. Tuthill, M. Withford, G. Duchêne

Proceedings Volume 11823, 118230C (2021) https://doi.org/10.1117/12.2594840

KEYWORDS: Telescopes, Wavefront sensors, Single mode fibers, Stars, Optical fibers, Interferometry, Diffraction, Wavefronts, Spatial resolution, Photonics

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Proceedings Article | 13 December 2020 Presentation + Paper

Presentation + Paper

Status of the SCExAO instrument: recent technology upgrades and path to a system-level demonstrator for PSI

Julien Lozi, Olivier Guyon, Sébastien Vievard, Ananya Sahoo, Vincent Deo, Nemanja Jovanovic, Barnaby Norris, Marc-Antoine Martinod, Ben Mazin, Alex Walter, Neelay Fruitwala, Sarah Steiger, Kristina Davis, Peter Tuthill, Tomoyuki Kudo, Hajime Kawahara, Takayuki Kotani, Michael Ireland, Theodoros Anagnos, Chrstian Schwab, Nick Cvetojevic, Elsa Huby, Sylvestre Lacour, Kevin Barjot, Tyler Groff, Jeffrey Chilcote, Jeremy Kasdin, Frantz Martinache, Romain Laugier, Mamadou N'Diaye, Justin Knight, Jared Males, Steven Bos, Frans Snik, David Doelman, Kelsey Miller, Eduardo Bendek, Ruslan Belikov, Eugene Pluzhnik, Thayne Currie, Masayuki Kuzuhara, Taichi Uyama, Jun Nishikawa, Naoshi Murakami, Jun Hashimoto, Yosuke Minowa, Christophe Clergeon, Yoshito Ono, Naruhisa Takato, Motohide Tamura, Hideki Takami, Masa Hayashi

Proceedings Volume 11448, 114480N (2020) https://doi.org/10.1117/12.2562832

KEYWORDS: Imaging systems, Telescopes, Infrared sensors, Infrared imaging, Coronagraphy, Wavefront sensors, Sensors, Detection and tracking algorithms, Cameras, Wavefronts

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Proceedings Article | 13 December 2020 Poster + Presentation + Paper

Poster + Presentation + Paper

Recent results on electro-optic visible multi-telescope beam combiner for next generation FIRST/SUBARU instruments: hybrid and passive devices

G. Martin, M. Foin, C. Cassagnettes, G. Ulliac, N. Courjal, K. Barjot, N. Cvetojevic, S. Vievard, V. Lapeyrere, E. Huby, S. Lacour

Proceedings Volume 11446, 1144626 (2020) https://doi.org/10.1117/12.2562171

KEYWORDS: Electro optics, 3D equipment, Visible radiation, Imaging spectroscopy, Beam splitters, Telescopes, Waveguides, Integrated optics, Glasses, Imaging systems

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Proceedings Article | 13 December 2020 Poster + Paper

Poster + Paper

FIRST, a pupil-remapping fiber interferometer at the Subaru Telescope: on-sky results

S. Vievard, E. Huby, S. Lacour, K. Barjot, G. Martin, N. Cvetojevic, V. Deo, O. Guyon, J. Lozi, T. Kotani, N. Jovanovic, F. Marchis, G. Duchêne, V. Lapeyrere, D. Rouan, G. Perrin

Proceedings Volume 11446, 1144629 (2020) https://doi.org/10.1117/12.2563033

KEYWORDS: Telescopes, Adaptive optics, Interferometers, Imaging systems, Single mode fibers, Interferometry, Spatial filters, Optical instrument design, Diffraction, Speckle

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Proceedings Article | 13 December 2020 Poster + Paper

Poster + Paper

Laboratory characterization of FIRSTv2 photonic chip for the study of substellar companions

K. Barjot, E. Huby, S. Vievard, N. Cvetojevic, S. Lacour, G. Martin, V. Deo, V. Lapeyrere, D. Rouan, O. Guyon, J. Lozi, N. Jovanovic, C. Cassagnettes, G. Perrin, F. Marchis, G. Duchêne, T. Kotani

Proceedings Volume 11446, 1144623 (2020) https://doi.org/10.1117/12.2561713

KEYWORDS: Telescopes, Imaging spectroscopy, Single mode fibers, Visible radiation, Interferometry, Microelectromechanical systems, Fiber characterization, Imaging systems, Spectroscopes, Diffraction

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Proceedings Article | 13 December 2020 Poster + Paper

Poster + Paper

A metrological characterization of the SPEED test-bed PIAACMC components

K. Barjot, P. Martinez, M. Beaulieu, C. Gouvret, A. Marcotto, O. Guyon, M. Belhadi, A. Caillat, T. Behaghel, J. M. Le Duigou, K. Dohlen, A. Vigan

Proceedings Volume 11451, 114513B (2020) https://doi.org/10.1117/12.2557112

KEYWORDS: Metrology, Mirrors, Coronagraphy, Apodization, Optics manufacturing, Image segmentation, Exoplanetary science, High angular resolution imaging, Spatial resolution, Large telescopes

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Showing 5 of 19 publications

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