  Optical metasurfaces have come into the spotlight as a promising platform for
light manipulation at the nanoscale, including ultrafast all-optical control
via excitation with femtosecond laser pulses. Recently, dichroic metasurfaces
have been exploited to modulate the polarization state of light with
unprecedented speed. Here, we theoretically predict and experimentally
demonstrate by pump-probe spectroscopy the capability to reconfigure the
ultrafast dichroic signal of a gold metasurface by simply acting on the
polarization of the pump pulse, which is shown to reshape the spatio-temporal
distribution of the optical perturbation. The photoinduced anisotropic
response, driven by out-of-equilibrium carriers and extinguished in a
sub-picosecond temporal window, is readily controlled in intensity by tuning
the polarization direction of the excitation up to a full sign reversal. This
work proves that nonlinear metasurfaces offer the flexibility to tailor their
ultrafast optical response in a fully all-optically reconfigurable platform.
