Efficient injection from large telescopes into single-mode fibres: enabling the era of ultra-precision astronomy

N. Jovanovic, C. Schwab, O. Guyon, J. Lozi, N. Cvetojevic, F. Martinache, S. Leon-Saval, B. Norris, S. Gross, D. Doughty, T. Currie, N. Takato

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Photonic technologies offer numerous advantages for astronomical instruments such as spectrographs and interferometers owing to their small footprints and diverse range of functionalities. Operating at the diffraction-limit, it is notoriously difficult to efficiently couple such devices directly with large telescopes. We demonstrate that with careful control of both the non-ideal pupil geometry of a telescope and residual wavefront errors, efficient coupling with single-mode devices can indeed be realised. A fibre injection was built within the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument. Light was coupled into a single-mode fibre operating in the near-IR (J-H bands) which was downstream of the extreme adaptive optics system and the pupil apodising optics. A coupling efficiency of 86% of the theoretical maximum limit was achieved at 1550 nm for a diffraction-limited beam in the laboratory, and was linearly correlated with Strehl ratio. The coupling efficiency was constant to within <30% in the range 1250-1600 nm. Preliminary on-sky data with a Strehl ratio of 60% in the H-band produced a coupling efficiency into a single-mode fibre of ~50%, consistent with expectations. The coupling was >40% for 84% of the time and >50% for 41% of the time. The laboratory results allow us to forecast that extreme adaptive optics levels of correction (Strehl ratio >90% in H-band) would allow coupling of >67% (of the order of coupling to multimode fibres currently) while standard levels of wavefront correction (Strehl ratio >20% in H-band) would allow coupling of >18%. For Strehl ratios <20%, few-port photonic lanterns become a superior choice but the signal-To-noise, and pixel availability must be considered. These results illustrate a clear path to efficient on-sky coupling into a single-mode fibre, which could be used to realise modal-noise-free radial velocity machines, very-long-baseline optical/near-IR interferometers and/or simply exploit photonic technologies in future instrument design.

LanguageEnglish
Article numberA122
Pages1-15
Number of pages15
JournalAstronomy and Astrophysics
Volume604
DOIs
Publication statusPublished - 1 Aug 2017

Fingerprint

astronomy
telescopes
injection
fibers
interferometer
diffraction
adaptive optics
photonics
pupils
footprint
interferometers
pixel
geometry
footprints
fibre
radial velocity
forecasting
spectrographs
availability
sky

Keywords

  • instrumentation: adaptive optics
  • instrumentation: high angular resolution
  • instrumentation: spectrographs
  • instrumentation: interferometers

Cite this

Jovanovic, N. ; Schwab, C. ; Guyon, O. ; Lozi, J. ; Cvetojevic, N. ; Martinache, F. ; Leon-Saval, S. ; Norris, B. ; Gross, S. ; Doughty, D. ; Currie, T. ; Takato, N. / Efficient injection from large telescopes into single-mode fibres : enabling the era of ultra-precision astronomy. In: Astronomy and Astrophysics. 2017 ; Vol. 604. pp. 1-15.
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abstract = "Photonic technologies offer numerous advantages for astronomical instruments such as spectrographs and interferometers owing to their small footprints and diverse range of functionalities. Operating at the diffraction-limit, it is notoriously difficult to efficiently couple such devices directly with large telescopes. We demonstrate that with careful control of both the non-ideal pupil geometry of a telescope and residual wavefront errors, efficient coupling with single-mode devices can indeed be realised. A fibre injection was built within the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument. Light was coupled into a single-mode fibre operating in the near-IR (J-H bands) which was downstream of the extreme adaptive optics system and the pupil apodising optics. A coupling efficiency of 86{\%} of the theoretical maximum limit was achieved at 1550 nm for a diffraction-limited beam in the laboratory, and was linearly correlated with Strehl ratio. The coupling efficiency was constant to within <30{\%} in the range 1250-1600 nm. Preliminary on-sky data with a Strehl ratio of 60{\%} in the H-band produced a coupling efficiency into a single-mode fibre of ~50{\%}, consistent with expectations. The coupling was >40{\%} for 84{\%} of the time and >50{\%} for 41{\%} of the time. The laboratory results allow us to forecast that extreme adaptive optics levels of correction (Strehl ratio >90{\%} in H-band) would allow coupling of >67{\%} (of the order of coupling to multimode fibres currently) while standard levels of wavefront correction (Strehl ratio >20{\%} in H-band) would allow coupling of >18{\%}. For Strehl ratios <20{\%}, few-port photonic lanterns become a superior choice but the signal-To-noise, and pixel availability must be considered. These results illustrate a clear path to efficient on-sky coupling into a single-mode fibre, which could be used to realise modal-noise-free radial velocity machines, very-long-baseline optical/near-IR interferometers and/or simply exploit photonic technologies in future instrument design.",
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author = "N. Jovanovic and C. Schwab and O. Guyon and J. Lozi and N. Cvetojevic and F. Martinache and S. Leon-Saval and B. Norris and S. Gross and D. Doughty and T. Currie and N. Takato",
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Jovanovic, N, Schwab, C, Guyon, O, Lozi, J, Cvetojevic, N, Martinache, F, Leon-Saval, S, Norris, B, Gross, S, Doughty, D, Currie, T & Takato, N 2017, 'Efficient injection from large telescopes into single-mode fibres: enabling the era of ultra-precision astronomy', Astronomy and Astrophysics, vol. 604, A122, pp. 1-15. https://doi.org/10.1051/0004-6361/201630351

Efficient injection from large telescopes into single-mode fibres : enabling the era of ultra-precision astronomy. / Jovanovic, N.; Schwab, C.; Guyon, O.; Lozi, J.; Cvetojevic, N.; Martinache, F.; Leon-Saval, S.; Norris, B.; Gross, S.; Doughty, D.; Currie, T.; Takato, N.

In: Astronomy and Astrophysics, Vol. 604, A122, 01.08.2017, p. 1-15.

Research output: Contribution to journalArticleResearchpeer-review

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T1 - Efficient injection from large telescopes into single-mode fibres

T2 - Astronomy and Astrophysics

AU - Jovanovic, N.

AU - Schwab, C.

AU - Guyon, O.

AU - Lozi, J.

AU - Cvetojevic, N.

AU - Martinache, F.

AU - Leon-Saval, S.

AU - Norris, B.

AU - Gross, S.

AU - Doughty, D.

AU - Currie, T.

AU - Takato, N.

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N2 - Photonic technologies offer numerous advantages for astronomical instruments such as spectrographs and interferometers owing to their small footprints and diverse range of functionalities. Operating at the diffraction-limit, it is notoriously difficult to efficiently couple such devices directly with large telescopes. We demonstrate that with careful control of both the non-ideal pupil geometry of a telescope and residual wavefront errors, efficient coupling with single-mode devices can indeed be realised. A fibre injection was built within the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument. Light was coupled into a single-mode fibre operating in the near-IR (J-H bands) which was downstream of the extreme adaptive optics system and the pupil apodising optics. A coupling efficiency of 86% of the theoretical maximum limit was achieved at 1550 nm for a diffraction-limited beam in the laboratory, and was linearly correlated with Strehl ratio. The coupling efficiency was constant to within <30% in the range 1250-1600 nm. Preliminary on-sky data with a Strehl ratio of 60% in the H-band produced a coupling efficiency into a single-mode fibre of ~50%, consistent with expectations. The coupling was >40% for 84% of the time and >50% for 41% of the time. The laboratory results allow us to forecast that extreme adaptive optics levels of correction (Strehl ratio >90% in H-band) would allow coupling of >67% (of the order of coupling to multimode fibres currently) while standard levels of wavefront correction (Strehl ratio >20% in H-band) would allow coupling of >18%. For Strehl ratios <20%, few-port photonic lanterns become a superior choice but the signal-To-noise, and pixel availability must be considered. These results illustrate a clear path to efficient on-sky coupling into a single-mode fibre, which could be used to realise modal-noise-free radial velocity machines, very-long-baseline optical/near-IR interferometers and/or simply exploit photonic technologies in future instrument design.

AB - Photonic technologies offer numerous advantages for astronomical instruments such as spectrographs and interferometers owing to their small footprints and diverse range of functionalities. Operating at the diffraction-limit, it is notoriously difficult to efficiently couple such devices directly with large telescopes. We demonstrate that with careful control of both the non-ideal pupil geometry of a telescope and residual wavefront errors, efficient coupling with single-mode devices can indeed be realised. A fibre injection was built within the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument. Light was coupled into a single-mode fibre operating in the near-IR (J-H bands) which was downstream of the extreme adaptive optics system and the pupil apodising optics. A coupling efficiency of 86% of the theoretical maximum limit was achieved at 1550 nm for a diffraction-limited beam in the laboratory, and was linearly correlated with Strehl ratio. The coupling efficiency was constant to within <30% in the range 1250-1600 nm. Preliminary on-sky data with a Strehl ratio of 60% in the H-band produced a coupling efficiency into a single-mode fibre of ~50%, consistent with expectations. The coupling was >40% for 84% of the time and >50% for 41% of the time. The laboratory results allow us to forecast that extreme adaptive optics levels of correction (Strehl ratio >90% in H-band) would allow coupling of >67% (of the order of coupling to multimode fibres currently) while standard levels of wavefront correction (Strehl ratio >20% in H-band) would allow coupling of >18%. For Strehl ratios <20%, few-port photonic lanterns become a superior choice but the signal-To-noise, and pixel availability must be considered. These results illustrate a clear path to efficient on-sky coupling into a single-mode fibre, which could be used to realise modal-noise-free radial velocity machines, very-long-baseline optical/near-IR interferometers and/or simply exploit photonic technologies in future instrument design.

KW - instrumentation: adaptive optics

KW - instrumentation: high angular resolution

KW - instrumentation: spectrographs

KW - instrumentation: interferometers

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