Dual-layer scalar vortex coronagraph concept

Abstract

Direct imaging of Earth-like exoplanets requires coronagraphic masks that provide high planet throughput and efficient broadband starlight rejection. We present the dual-layer dimpled scalar vortex coronagraph, an achromatic scalar vortex architecture that uses two materials with complementary dispersion properties to achieve broadband starlight suppression. By optimizing material selection and layer topographies, we overcome the impractical thicknesses of prior multilayer designs and identify an achromatic charge-six vortex design compatible with demonstrated fabrication techniques. Numerical simulations predict broadband starlight suppression on the order of 10−10 contrast over 20% bandwidth at the inner working angle of the coronagraph. The proposed architecture provides a viable path toward high-performance, achromatic focal plane masks for future space-based coronagraphs to detect and characterize exoplanets.