Integrated optics for astronomical interferometry. II. First laboratory white-light interferograms

TL;DR

This paper demonstrates the first laboratory white-light interferograms using integrated optics beam combiners, validating their potential for astronomical interferometry despite using non-optimized, off-the-shelf components.

Contribution

It provides the first laboratory validation of integrated optics beam combiners for white-light interferometry in astronomy, showing high contrast and throughput with off-the-shelf components.

Findings

Achieved stable contrasts over 93% with laser source.

Obtained up to 78% contrast with white-light source.

Demonstrated throughput of 27-43% depending on the device.

Abstract

We report first white-light interferograms obtained with an integrated optics beam combiner on a glass plate. These results demonstrate the feasability of single-mode interferometric beam combination with integrated optics technology presented and discussed in paper I. The demonstration is achieved in laboratory with off-the-shelves components coming from micro-sensor applications, not optimized for astronomical use. These two-telescope beam combiners made by ion exchange technique on glass substrate provide laboratory white-light interferograms simultaneously with photometric calibration. A dedicated interferometric workbench using optical fibers is set up to characterize these devices. Despite the rather low match of the component parameters to astronomical constraints, we obtain stable contrasts higher than 93% with a 1.54-\micron laser source and up to 78% with a white-light source in the astronomical H band. Global throughput of 27% for a potassium ion exchange beam combiner and of 43% for a silver one are reached. This work validates our approach for combining several stellar beams of a long baseline interferometer with integrated optics components.