Si-based integrated optics for stellar interferometry imaging

Stellar interferometry is an old technique (first successful measurement of Titan diameter by Michelson in 1890), which have recently been dramatically improved by the implementation of integrated optical devices. The technique, consisting in combining coherently several beams coming from distinct telescopes, allows to reconstruct images with a very high angular resolution, typically 10 times better than the diffraction limit of the biggest telescopes on Earth and about 20 times better than the Hubble space telescope. During the last few years, LETI, in collaboration with IMEP (Institut de MicroElectronique et Photonique) and LAOG (Laboratoire d'Astrophysique de l'Observatoire de Grenoble) has developed several components for stellar interferometry, either using its well-established silica on silicon technology, or developing a new silicon technology for mid-infrared metallic hollow waveguides adapted for the ESADARWIN mission. This paper will present the latest developments made by LETI in this field, describing the silicon technologies involved, the realized devices as well as their behaviour on laboratory set-ups or on the sky