  Energetic spin-polarized positrons are extremely demanded for forefront
researches, such as $e^- e^+$ collider physics, but making compact positron
sources is still very challenging. Here we put forward an efficient scheme of
trapping and acceleration of polarized positrons in plasma wakefields. Seed
electrons colliding with a bichromatic laser create polarized $\gamma$ photons
which then split into $e^- e^+$ pairs via nonlinear Breit-Wheeler process with
an average (partial) positron polarization above 30\% (70\%). Over 70\%
positrons are trapped and accelerated in recovered wakefields driven by a
hollow electron beam, obtaining an energy gain of 3.5 GeV/cm with slight
depolarization. This scheme provides a potential for constructing compact and
economical positron sources for future applications.
