Spatial filtering for the Large Interferometer For Exoplanets (LIFE) mission

Infrared nulling interferometry in space is the most promising technique for detecting possible signs of life on earth-like exoplanets, through the combination of ozone and other biomarkers. The Large Interferometer for Exoplanets (LIFE) mission extends on earlier work by Darwin and Terrestrial Planet Finder Interferometer (TPF-I) with a modern mission concept. In this paper, we describe why spatial filtering is critical in the context of both adaptive nulling and alternative approaches in order to achieve the ∼10⁷ contrast needed, and why a endlessly single mode photonics crystal waveguide fed by phase induced amplitude apodization optics is the currently preferred option for LIFE. Finally, we discuss the considered technological options and prototyping for production of such a waveguide spatial filter at different wavelengths, including both fibres and laser micromachining of infrared crystals.