Collisional absorption of a weak high-frequency linearly polarized electromagnetic wave by a plasma located in a strong laser field is studied. It is shown that the character of absorption essentially depends on the polarization of the weak laser wave relative to the intense one. Conditions for negative absorption are derived. Prospects for experimental demonstration of this effect are discussed.

• Received 27 August 1993

DOI:https://doi.org/10.1103/PhysRevE.48.4659