Electron-positron pair creation by a multimode field of an optical laser

The investigation of the electric field of modern powerful optical lasers predicts the creation of a dense quasiparticle plasma in the foci of counter-propagating optical laser beams. One more way for experimental proof of plasma creation is an experiment with two-mode laser beams, which are considered as a superposition of two monochromatic waves with commensurable frequencies. We investigate this problem in the framework of the quantum kinetics formulation. The resulting kinetic equation for the distribution function contains a source term describing the vacuum quasiparticle creation in a homogeneous external field. The total quasiparticle number density can be found as a moment of the distribution function. The time dependence of the pair density for the case of one- and two-mode fields and the case of two-mode fields with different frequency coefficient of proportionality are considered.