We consider emission of a photon by an electron in the field of a strong laser wave and production of e⁺e^- pair by a high-energy photon in the field of a strong laser wave. A probability of these processes for circularly or linearly polarized laser photons and for arbitrary polarization of all other particles is calculated. We obtain the complete set of functions which describes such a probability in a compact invariant form. Besides, we discuss the polarization effects in the kinematics relevant to the problem of e\to \gamma conversion at \gamma \gamma and \gamma e colliders.

PACS numbers: 12.20.--m, 42.50.Ct