%0 Journal Article
%T First fringes with an integrated-optics beam combiner at 10 μm. A new step towards instrument miniaturization for mid-infrared interferometry
%+ Institut de Planétologie et d'Astrophysique de Grenoble (IPAG )
%A Labadie, L.
%A Martín, G.
%A Anheier, N. C.
%A Arezki, B.
%A Qiao, H. A.
%A Bernacki, B.
%A Kern, P.
%< avec comité de lecture
%@ 0004-6361
%J Astronomy and Astrophysics - A&A
%I EDP Sciences
%V 531
%8 2011
%D 2011
%Z 1104.2899
%Z 2011A&A...531A..48L
%R 10.1051/0004-6361/201116727
%K instrumentation: high angular resolution
%K instrumentation: interferometers
%K methods: laboratory
%K techniques: interferometric
%Z Sciences of the Universe [physics]
%Z Sciences of the Universe [physics]/Astrophysics [astro-ph]Journal articles
%X Context. Observations of milliarcsecond-resolution scales and high dynamic range hold a central place in the exploration of distant planetary systems in order to achieve, for instance, the spectroscopic characterization of exo-Earths or the detailed mapping of their protoplanetary disc birthplace. Multi-aperture infrared interferometry, either from the ground or from space, is a very powerful technique to tackle these goals. However, significant technical efforts still need to be undertaken to achieve a simplification of these instruments if we wish to recombine the light from a large number of telescopes. Integrated-optics concepts appear to be a suitable alternative to the current conventional designs, especially if their use can be extended to a higher number of astronomical bands.
Aims: This article reports, for the first time to our knowledge, the experimental demonstration of the feasibility of an integrated-optics approach to mid-infrared beam combination for single-mode stellar interferometry.
Methods: We fabricated a two-telescope beam combiner prototype integrated on a substrate of chalcogenide glass, a material transparent from ~1 μm to ~14 μm. We developed laboratory tools to characterize in the mid-infrared the modal properties and the interferometric capabilities of our device.
Results: We obtain interferometric fringes at 10 μm and measure a mean contrast V = 0.981 ± 0.001 with high repeatability over one week and high stability over a time-period of ~5 h. We show experimentally - as well as on the basis of modeling considerations - that the component has a single-mode behavior at this wavelength, which is essential to achieve high-accuracy interferometry. From previous studies, the propagation losses are estimated to be 0.5 dB/cm for this type of component. We also discuss possible issues that may impact the interferometric contrast.
Conclusions: The IO beam combiner performs well at the tested wavelength. We also anticipate the requirement of a closer matching between the numerical apertures of the component and the (de)coupling optics to optimize the total throughput. The next step foreseen is the achievement of wide-band interferograms.
%G English
%2 https://insu.hal.science/insu-03624667/document
%2 https://insu.hal.science/insu-03624667/file/aa16727-11.pdf
%L insu-03624667
%U https://insu.hal.science/insu-03624667
%~ INSU
%~ UNIV-SAVOIE
%~ UGA
%~ CNRS
%~ UNIV-GRENOBLE1
%~ INPG
%~ IRSTEA
%~ CNES
%~ OSUG
%~ IPAG
%~ AGREENIUM
%~ INRAE
%~ USMB-COMUE