  We present designs for fully achromatic vector Apodizing Phase Plate (vAPP)
coronagraphs, that implement low polarization leakage solutions and achromatic
beam-splitting, enabling observations in broadband filters. The vAPP is a pupil
plane optic, inducing the phase through the inherently achromatic geometric
phase. We discuss various implementations of the broadband vAPP and set
requirements on all the components of the broadband vAPP coronagraph to ensure
that the leakage terms do not limit a raw contrast of 1E-5. Furthermore, we
discuss superachromatic QWPs based of liquid crystals or quartz/MgF2
combinations, and several polarizer choices. As the implementation of the
(broadband) vAPP coronagraph is fully based on polarization techniques, it can
easily be extended to furnish polarimetry by adding another QWP before the
coronagraph optic, which further enhances the contrast between the star and a
polarized companion in reflected light. We outline several polarimetric vAPP
system designs that could be easily implemented in existing instruments, e.g.
SPHERE and SCExAO.
