Modal filtering for nulling interferometry

L. Labadie; P. Labeye; P. Kern; I. Schanen; B. Arezki; J.-E. Broquin

doi:doi:10.1051/0004-6361:20053407

Free access

Issue		A&A Volume 450, Number 3, May II 2006


Page(s)		1265 - 1266
Section		Instruments, observational techniques, and data processing
DOI		http://dx.doi.org/10.1051/0004-6361:20053407

A&A 450, 1265-1266 (2006)
DOI: 10.1051/0004-6361:20053407

First single-mode conductive waveguides in the mid-infrared

L. Labadie¹, P. Labeye², P. Kern¹, I. Schanen³, B. Arezki¹ and J.-E. Broquin³

¹ Laboratoire d'Astrophysique de l'Observatoire de Grenoble, BP 53, 38041 Grenoble Cedex 9, France
e-mail: lucas.labadie@obs.ujf-grenoble.fr
² Laboratoire d'Électronique et des Technologies de l'Information (LETI), CEA-DRT-LETI, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France
³ Institut de Microélectronique et Photonique, UMR 5130, 23 rue des Martyrs, BP 257, 38016 Grenoble Cedex 1, France

(Received 11 May 2005 / Accepted 4 November 2005)

Abstract
We have investigated the manufacturing and characterization of first single-mode conductive waveguides to be used as modal filters for nulling interferometry in the mid-infrared range [ 4-20 $\mu$ m] . As a very high dynamic range is mandatory for the detection of Earth-like planets, modal filtering is a crucial instrumental aspect. The hollow metallic waveguides (HMW) presented here are manufactured using micro-machining techniques. Single-mode behavior has been investigated in the laboratory through polarization analysis and transmission features have been measured using relative flux comparison. Single-mode behavior was assessed at $\lambda=10.6~\mu$ m for rectangular waveguides with dimensions $a=10~\mu$ m and $b\le5.3~\mu$ m with an accuracy of ~2.5%. The tests showed that a single-polarization state can be maintained in the waveguide. A comparison with results on multi-mode HMW is given. Excess losses of 2.4 dB (~58% transmission) have been measured for a single-mode waveguide. In particular, the importance of coupling conditions in the waveguide is emphasized here. The goal of manufacturing and characterizing the first single-mode HMW for the mid-infrared has been achieved. This opens the road to the use of integrated optics for interferometry in this spectral range.

Key words: instrumentation: interferometers -- methods: laboratory -- methods: data analysis

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