Demonstration of an efficient, photonic-based astronomical spectrograph on an 8-m telescope

N. Jovanovic, N. Cvetojevic, B. Norris, C. Betters, C. Schwab, J. Lozi, O. Guyon, S. Gross, F. Martinache, P. Tuthill, D. Doughty, Y. Minowa, N. Takato, J. Lawrence

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


We demonstrate for the first time an efficient, photonic-based astronomical spectrograph on the 8-m Subaru Telescope. An extreme adaptive optics system is combined with pupil apodiziation optics to efficiently inject light directly into a single-mode fiber, which feeds a compact cross-dispersed spectrograph based on array waveguide grating technology. The instrument currently offers a throughput of 5% from sky-to-detector which we outline could easily be upgraded to ~ 13% (assuming a coupling efficiency of 50%). The isolated spectrograph throughput from the single-mode fiber to detector was 42% at 1550 nm. The coupling e ciency into the single-mode fiber was limited by the achievable Strehl ratio on a given night. A coupling efficiency of 47% has been achieved with ~ 60% Strehl ratio on-sky to date. Improvements to the adaptive optics system will enable 90% Strehl ratio and a coupling of up to 67% eventually. This work demonstrates that the unique combination of advanced technologies enables the realization of a compact and highly efficient spectrograph, setting a precedent for future instrument design on very-large and extremely-large telescopes.

Original languageEnglish (US)
Pages (from-to)17753-17766
Number of pages14
JournalOptics Express
Issue number15
StatePublished - Jul 24 2017

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


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