Phase conjugation at the surfaces of optically excited CuI films

The possibility of realizing an optical phase conjugation in an excited semiconductor medium is shown theoretically and experimentally. A phase conjugation is revealed for the photon energy equal to half the energy of the radiative recombination of excitons in CuI films pumped by a nitrogen laser at room temperature. The dependences of the phase-conjugation signal intensity on its spectral composition are investigated. The quadratic interaction of light and exciton electromagnetic oscillations in the semiconductor medium is suggested as an explanation of this effect.