Efficient photonic reformatting of celestial light for diffraction-limited spectroscopy
MacLachlan, D.G.; Harris, R.J.; Gris-Sánchez, I.; Morris, T.J.; Choudhury, D.; Gendron, E.; Basden, A.G.; Spaleniak, I.; Arriola, A.; Birks, T.A.; Allington-Smith, J.R.; Thomson, R.R.
Professor Timothy Morris firstname.lastname@example.org
Dr Alastair Basden email@example.com
Hpc Technical Manager
The spectral resolution of a dispersive astronomical spectrograph is limited by the trade-off between throughput and the width of the entrance slit. Photonic guided wave transitions have been proposed as a route to bypass this trade-off, by enabling the efficient reformatting of incoherent seeing-limited light collected by the telescope into a linear array of single modes: a pseudo-slit which is highly multimode in one axis but diffraction-limited in the dispersion axis of the spectrograph. It is anticipated that the size of a single-object spectrograph fed with light in this manner would be essentially independent of the telescope aperture size. A further anticipated benefit is that such spectrographs would be free of ‘modal noise’, a phenomenon that occurs in high-resolution multimode fibre-fed spectrographs due to the coherent nature of the telescope point spread function (PSF). We seek to address these aspects by integrating a multicore fibre photonic lantern with an ultrafast laser inscribed three-dimensional waveguide interconnect to spatially reformat the modes within the PSF into a diffraction-limited pseudo-slit. Using the CANARY adaptive optics (AO) demonstrator on the William Herschel Telescope, and 1530 ± 80 nm stellar light, the device exhibits a transmission of 47–53 per cent depending upon the mode of AO correction applied. We also show the advantage of using AO to couple light into such a device by sampling only the core of the CANARY PSF. This result underscores the possibility that a fully optimized guided-wave device can be used with AO to provide efficient spectroscopy at high spectral resolution.
MacLachlan, D., Harris, R., Gris-Sánchez, I., Morris, T., Choudhury, D., Gendron, E., …Thomson, R. (2017). Efficient photonic reformatting of celestial light for diffraction-limited spectroscopy. Monthly Notices of the Royal Astronomical Society, 464(4), 4950-4957. https://doi.org/10.1093/mnras/stw2558
|Journal Article Type||Article|
|Acceptance Date||Oct 6, 2016|
|Online Publication Date||Oct 6, 2016|
|Publication Date||Feb 1, 2017|
|Deposit Date||Jul 26, 2017|
|Publicly Available Date||Jul 26, 2017|
|Journal||Monthly Notices of the Royal Astronomical Society|
|Publisher||Royal Astronomical Society|
|Peer Reviewed||Peer Reviewed|
Published Journal Article
This article has been accepted for publication in Monthly notices of the Royal Astronomical Society ©: 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
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