  We show that a metastable $\eta$--pairing superconducting phase can be
induced by photodoping doublons and holes into a strongly repulsive fermionic
Hubbard model. The doublon-hole condensate originates from an intrinsic
doublon-hole exchange interaction and does not rely on the symmetry of the
half-filled Hubbard model. It extends over a wide range of doublon densities
and effective temperatures. Different non-equilibrium protocols to realize this
state are proposed and numerically tested. We also study the optical
conductivity in the superconducting phase, which exhibits ideal metallic
behavior, i.e., a delta function at zero-frequency in the conductivity, in
conjunction with a negative conductivity at large frequencies. These
characteristic optical properties can provide a fingerprint of the
$\eta$-pairing phase in pump-probe experiments.
