Integrated optics components for stellar interferometry

TL;DR

This paper presents an integrated optics component for stellar interferometry that enables simultaneous measurement of multiple telescope pairs, optimized for achromatic performance, and validated through optical characterization, advancing multi-telescope interferometric instrumentation.

Contribution

It introduces a novel integrated optics component for coherent beam recombination in stellar interferometry, with achromatic behavior and phase control, suitable for multi-telescope arrays.

Findings

Optical characterization confirms theoretical predictions.

Component design is extendable to other spectral bands and telescope numbers.

Potential application as a fringe tracker in interferometric systems.

Abstract

It has been recently demonstrated that integrated optics could enhance accuracy, stability, and ease of use of stellar interferometry techniques. The subject of this thesis is the study of an optical component based on singlemode waveguides for the coherent recombining of optical beams coming from four telescopes. Proposed architecture provides a simultaneous an instantaneous measurement of complex visibility of interferometric signals of the six possible pairs of telescopes. The component is optimized for achromatic behaviour over the H spectral transparency band of atmosphere and integrates an original achromatic phase shifter in order to obtain four phase quadrature states of interferometric fringes. Optical characterisation results obtained on devices realized by deposition and etching of silica layers on silicon substrate confirm theoretical predictions et enabled the study of more complex components at the heart of second generation instrumentation projects of the VLTI (Very Large Telescope Interferometer) This study shows that proposed architecture can be extended to J and K spectral bands, can be applied for the recombination of beams coming from six and even eight telescopes and could also be applied to realise a fringe tracker.