  In recent time, the optical-analogous skyrmions, topological quasiparticles
with sophisticated vectorial structures, have received an increasing amount of
interest. Here we propose theortically and experimentally a generalized family
of these, the tunable optical skyrmion, unveiling a new mechanism to transform
between various skyrmionic topologies, including N\'eel-, Bloch-, and
antiskyrmion types, via simple parametric tuning. In addition, Poincar\'e-like
geometric representation is proposed to visualize the topological evolution of
tunable skyrmions, which we termed Skyrme-Poincar\'e sphere, akin to the
spin-orbit representation of complex vector modes. To generate experimentally
the tunable optical skyrmions we implemented a digital hologram system based on
a spatial light modulator, showing great agreement with our theoretical
prediction.
