  Two oppositely charged particles created within a microscopic space-time
region can be separated, accelerated over a much larger distance, and brought
to a recollision by a laser field. Consequently, new reactions become feasible,
where the energy absorbed by the particles is efficiently released. By
investigating the laser-dressed polarization operator, we identify a new
contribution describing high-energy recollisions experienced by an
electron-positron pair generated by pure light when a gamma photon impinges on
an intense, linearly polarized laser pulse. The energy absorbed in the
recollision process over the macroscopic laser wavelength corresponds to a
large number of laser photons and can be exploited to prime high-energy
reactions. Thus, the recollision contribution to the polarization operator
differs qualitatively and quantitatively from the well-known one, describing
the annihilation of an electron-positron pair within the microscopic formation
region.
