Universität zu Köln

Tepper, Jan, Labadie, Lucas ORCID: 0000-0001-5342-5713, Gross, Simon ORCID: 0000-0001-5130-183X, Arriola, Alexander, Minardi, Stefano, Diener, Romina and Withford, Michael J. (2017). Ultrafast laser inscription in ZBLAN integrated optics chips for mid-IR beam combination in astronomical interferometry. Opt. Express, 25 (17). S. 20642 - 20654. WASHINGTON: OPTICAL SOC AMER. ISSN 1094-4087

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Abstract

Astronomical interferometry is a unique technique that allows observation with angular resolutions on the milliarcsec scale by combining the light of several apertures hundreds of meters apart. The PIONIER and GRAVITY instruments at the Very Large Telescope Interferometer have demonstrated that silica-based integrated optics (IO) provide a small-scale and highly stable solution for the interferometric beam combination process. Yet, important science cases such as exoplanet hunting or the spectroscopic characterization of exoplanetary atmospheres are favorable for observation in the mid-IR, namely the atmospheric windows L and L' band (3-4 mu m), a wavelength range that is not covered by conventional silica-based IO. Here, we propose laser-inscribed IO 2 x 2 couplers in ZBLAN and experimentally assess the critical properties of the component for broadband mid-IR interferometry. We measure the splitting ratio over the 2.5 to 5.0 mu m range and find excellent broadband contrast over the L (3.1-3.6 mu m) and L' (3.6 - 4.0 mu m) bands. Furthermore, we quantify the dispersion properties of the coupler and find a phase variation as low as 0.02 rad across the L and L' band, respectively. By optimizing the NA of our injection beam, we measured a very high total throughput of 58% over the L band including Fresnel reflection and coupling losses. We also compare our findings to recent advances in mid-IR IO in GLS and discuss its advantages and disadvantages for the implementation in future mid-IR interferometers. (C) 2017 Optical Society of America

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Tepper, Jan UNSPECIFIED UNSPECIFIED UNSPECIFIED Labadie, Lucas UNSPECIFIED orcid.org/0000-0001-5342-5713 UNSPECIFIED Gross, Simon UNSPECIFIED orcid.org/0000-0001-5130-183X UNSPECIFIED Arriola, Alexander UNSPECIFIED UNSPECIFIED UNSPECIFIED Minardi, Stefano UNSPECIFIED UNSPECIFIED UNSPECIFIED Diener, Romina UNSPECIFIED UNSPECIFIED UNSPECIFIED Withford, Michael J. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-221610
DOI:	10.1364/OE.25.020642
Journal or Publication Title:	Opt. Express
Volume:	25
Number:	17
Page Range:	S. 20642 - 20654
Date:	2017
Publisher:	OPTICAL SOC AMER
Place of Publication:	WASHINGTON
ISSN:	1094-4087
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Physics > Institute of Physics I
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language WAVE-GUIDES; CHALCOGENIDE GLASS; FABRICATION; ASYMMETRY; PLANETS; LIGHT; GAP Multiple languages Optics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/22161