Vector vortex coronagraphy for exoplanet detection with spatially variant diffractive waveplates

Optical vortex coronagraphs have recently been deployed on most of the world’s largest ground-based telescopes to assist in the search for faint exoplanets and dust emission near stars. These instruments typically make use of vector vortex phase masks, and at short near-infrared wavelengths, the phase masks tend to be spatially variant liquid-crystal-polymer-based diffractive waveplates. Optical vortex coronagraphs also hold great promise as a potential means of imaging terrestrial exoplanets in nearby solar systems with space-based telescopes, for which nearly ideal vortex phase masks will be needed. Here, we briefly summarize the optical vortex coronagraph, foreseen performance requirements for terrestrial exoplanet imaging detection, the obstacles to nearly ideal diffractive-waveplate-based vortex phase masks, and recent broadband performance demonstrations.