Photonic spatial reformatting of stellar light for diffraction-limited spectroscopy

R. J. Harris*, David Guillaume MacLachlan, Debaditya Choudhury, T. J. Morris, E. Gendron, A. G. Basden, G. Brown, J. R. Allington-Smith, Robert R Thomson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

49 Citations (Scopus)
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The spectral resolution of a dispersive spectrograph is dependent on the width of the entrance slit. This means that astronomical spectrographs trade-off throughput with spectral resolving power. Recently, optical guided-wave transitions known as photonic lanterns have been proposed to circumvent this trade-off, by enabling the efficient reformatting of multimode light into a pseudo-slit which is highly multimode in one axis, but diffraction-limited in the other. Here, we demonstrate the successful reformatting of a telescope point spread function into such a slit using a three-dimensional integrated optical waveguide device, which we name the photonic dicer. Using the CANARY adaptive optics (AO) demonstrator on the William Herschel Telescope, and light centred at 1530 nm with a 160 nm full width at half-maximum, the device shows a transmission of between 10 and 20 per cent depending upon the type of AO correction applied. Most of the loss is due to the overfilling of the input aperture in poor and moderate seeing. Taking this into account, the photonic device itself has a transmission of 57 ± 4 per cent. We show how a fully-optimized device can be used with AO to provide efficient spectroscopy at high spectral resolution.

Original languageEnglish
Pages (from-to)428-434
Number of pages7
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Publication statusPublished - 11 Jun 2015


  • Globular clusters: general
  • Globular clusters: individual: NGC 5286
  • Stars: abundances

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics


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