  The control of polarization, an essential property of light, is of wide
scientific and technological interest. Polarizer is an indispensable optical
element for direct polarization generations. Except common linear and circular
polarizations, however, arbitrary polarization generation heavily resorts to
bulky optical components by cascading linear polarizers and waveplates. Here,
we present a general strategy for designing all-in-one full Poincar\'e sphere
polarizers based on perfect arbitrary polarization conversion dichroism, and
realize it in a monolayer all-dielectric metasurface. It allows preferential
transmission and conversion of one polarization state locating at an arbitrary
position of the Poincar\'e sphere to its handedness-flipped state, while
completely blocking its orthogonal state. In contrast to previous work with
limited flexibility to only linear or circular polarizations, our method
manifests perfect dichroism close to 100% in theory and exceeding 90% in
experiments for arbitrary polarization states. Leveraging this tantalizing
dichroism, our demonstration of monolithic full Poincar\'e sphere polarization
generators directly from unpolarized light can enormously extend the scope of
meta-optics and dramatically push the state-of-the-art nanophotonic devices.
