Technology challenges for space interferometry: the option of mid-infrared integrated optics

TL;DR

This paper explores the development of mid-infrared integrated optics beam combiners for space interferometry, aiming to improve starlight cancellation for exoplanet observation missions like Darwin.

Contribution

It introduces the concept of using integrated optics for beam combination in mid-infrared space interferometry and reviews manufacturing solutions for such devices.

Findings

Review of dielectric and metallic waveguide solutions

Potential for simplified instrument design

Advancement in mid-infrared photonics devices

Abstract

Nulling interferometry is a technique providing high angular resolution which is the core of the space missions Darwin and the Terrestrail Planet Finder. The first objective is to reach a deep degree of starlight cancelation in the range 6 -- 20 microns, in order to observe and to characterize the signal from an Earth-like planet. Among the numerous technological challenges involved in these missions, the question of the beam combination and wavefront filtering has an important place. A single-mode integrated optics (IO) beam combiner could support both the functions of filtering and the interferometric combination, simplifying the instrumental design. Such a perspective has been explored in this work within the project Integrated Optics for Darwin (IODA), which aims at developing a first IO combiner in the mid-infrared. The solutions reviewed here to manufacture the combiner are based on infrared dielectric materials on one side, and on metallic conductive waveguides on the other side. With this work, additional inputs are offered to pursue the investigation on mid-infrared photonics devices.