  Superconductivity in the cuprates is characterized by spatial inhomogeneity
and an anisotropic electronic gap of d-wave symmetry. The aim of this work is
to understand how this anisotropy affects the non-equilibrium electronic
response of high-Tc superconductors. We compare the nodal and antinodal
non-equilibrium response to photo-excitations with photon energy comparable to
the superconducting gap and polarization along the Cu-Cu axis of the sample.
The data are supported by an effective d-wave BCS model indicating that the
observed enhancement of the superconducting transient signal mostly involves an
increase of pair coherence in the antinodal region, which is not induced at the
node.
