Nulling Interferometry with Optical Fibers and Photonic Lanterns

The combination of diffraction due to a telescope’s finite pupil diameter and scattering due to imperfect wavefronts leads to bright halos of light surrounding typical stellar images. This severely limits a telescope’s ability to detect faint sources near bright stars, such as that from exoplanets and circumstellar dust. As a result, optical techniques that enable high contrast observations at the smallest possible angular separations are of great interest. Interfering the light arriving at different parts of a telescope aperture (sub-apertures) can potentially yield improved resolution, and appropriately phasing the sub apertures can interferometrically suppress (null) starlight. This technique of nulling interferometry [1] across a telescope’s aperture can enable observations closer to a star than classical full-aperture coronagraphic imaging, providing access to separations where exoplanets are expected to be brighter and more numerous.