A resonance, induced by a DC field in a two-photon transition of an atom between states with opposite parity, results in a number of new effects related to the polarization of photons. These effects are caused by the interference of the non-resonant second-order dipole-forbidden amplitude and of a resonant part of the DC field-induced third-order amplitude. The linear and circular dichroism for the cross section of the process is revealed and analysed in detail for a two-photon excitation of the state from the ground state with a resonance on an state, induced by a DC electric field. The numerical data for alkali atoms demonstrate that the effects have quantitative characteristics of sufficiently large magnitudes and may be observed in experiments.