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

Jovanovic, N. and Schwab, C. and Guyon, O. and Lozi, J. and Cvetojevic, N. and Martinache, F. and Leon-Saval, S. and Norris, B. and Gross, S. and Doughty, D. and Currie, T. and Takato, N. (2017) Efficient injection from large telescopes into single-mode fibres: Enabling the era of ultra-precision astronomy. Astronomy and Astrophysics, 604 . Art. No. A122. ISSN 0004-6361.

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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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Schwab, C.0000-0002-4046-987X
Guyon, O.0000-0002-1097-9908
Lozi, J.0000-0002-3047-1845
Martinache, F.0000-0003-1180-4138
Gross, S.0000-0001-5130-183X
Currie, T.0000-0002-7405-3119
Additional Information:© ESO, 2017. Received 23 December 2016 / Accepted 14 June 2017. The authors acknowledge support from the JSPS (Grant-in-Aid for Research #23340051, #26220704 #23103002). This work was supported by the Astrobiology Center (ABC) of the National Institutes of Natural Sciences, Japan and the directors contingency fund at Subaru Telescope. This research was also supported by the Australian Research Council Centre of Excellence for Ultrahigh bandwidth Devices for Optical Systems (project number CE110001018). The authors wish to recognise and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.
Funding AgencyGrant Number
Japan Society for the Promotion of Science (JSPS)23340051
Japan Society for the Promotion of Science (JSPS)26220704
Japan Society for the Promotion of Science (JSPS)23103002
National Institutes of Natural Sciences of JapanUNSPECIFIED
Subaru TelescopeUNSPECIFIED
Australian Research CouncilCE110001018
Subject Keywords:instrumentation: adaptive optics / instrumentation: high angular resolution / instrumentation: spectrographs / instrumentation: interferometers
Record Number:CaltechAUTHORS:20181130-105341166
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Official Citation: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 and N. Takato A&A, 604 (2017) A122 DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:91364
Deposited By: George Porter
Deposited On:03 Dec 2018 16:10
Last Modified:09 Mar 2020 13:19

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