Phase control of Schwinger pair production by colliding laser pulses

We study the Schwinger electron-positron pair production by a strong electromagnetic field of two colliding e-polarized laser pulses with a relative phase shift $\Psi$. The spatio-temporal distribution of created pairs is very sensitive to this phase shift and to polarization of the pulses. We study this dependence in detail and demonstrate how it can be explained in terms of the underlying invariant field structure of the counterpropagating focused pulses.