Recent progress in vector vortex coronagraphy

The optical vortex coronagraph has great potential for enabling high-contrast observations very close to bright stars, and thus for reducing the size of space telescopes needed for exoplanet characterization missions. Here we discuss several recent developments in optical vortex coronagraphy. In particular, we describe multi-stage vortex configurations that allow the use of on-axis telescopes for high-contrast coronagraphy, and also enable the direct measurement of the amplitudes and phases of focal plane speckles. We also briefly describe recent laboratory demonstrations of the optical properties of the dual-stage vortex, and of the broadband performance of single stage vortex masks. Indeed, the demonstrated performance of the vector vortex phase masks already in hand, ≈ 10^(-8), is approximately that needed for an initial coronagraphic mission, such as an exoplanet explorer, aimed at detecting exozodiacal light and jovian exoplanets.