Mechanism for phase conjugation of the beam from a flowing-gas CO laser

A mechanism for the interaction of light with a nonlinear medium which leads to an efficient phase conjugation of the beam from a flowing-gas CO laser has been studied. The interaction occurs in four-wave mixing with a feedback loop. The interaction of the light with the active gain medium results from the formation of large-scale amplitude gratings in the medium. These gratings are created by copropagating pump waves.