  We investigate electron-positron pair creation in the interaction of a
nuclear Coulomb field and a highly intense two-mode laser field. For
bichromatic laser fields, we examine the differences arising for commensurable
and incommensurable frequencies in a continuous variation of the laser
frequency ratio and the quantum interference effects, which may occur in the
commensurable case. We show that the interference manifests in the angular
distributions and the total pair-production rates of the created particles.
Additionally, by varying the amplitudes of the two modes we study pair creation
in a monochromatic laser wave of arbitrarily elliptical polarization.
