  Conventional polarizers and polarization beam splitters have a fundamental
limit of 50\% efficiency when converting unpolarized light into one specific
polarization. Here, we overcome this restriction and achieve near-complete
conversion of unpolarized light to a single pure polarization state at several
outputs of topology-optimized metasurfaces. Our fabricated metasurface achieves
an extinction ratio approaching 100, when characterized with laboratory
measurements. We further demonstrate that arbitrary power splitting can be
achieved between three or more polarized outputs, offering flexibility in
target illumination. Our results provide a path toward greatly improving the
efficiency of common unpolarized light sources in a variety of applications
requiring pure polarizations.
