Based on strong-field QED in the Furry picture we use the Dirac-Volkov propagator to derive a compact expression for the differential emission probability of the two-photon Compton process in a pulsed intense laser field. The relation of real and virtual intermediate states is discussed, and the natural regularization of the on-shell contributions due to the finite laser pulse is highlighted. The inclusive two-photon spectrum is 2 orders of magnitude stronger than expected from a perturbative estimate.

• Received 21 September 2011

DOI:https://doi.org/10.1103/PhysRevD.85.101701