Coulomb collisions between nonequilibrium electrons during interband interaction of high-power optical pulses with semiconductors and insulators

A diffusion expansion is obtained for the integrals of Coulomb collisions between nonequilibrium electrons which are responsible for relaxation of the particle distribution functions and polarization induced by interband interaction of a high-power optical pulse with semiconductors and insulators. An analysis is made of the effect of Coulomb collisions on the coherence of the interaction between the field and the medium.