degenerate four-wave mixing


degenerate four-wave mixing

[di′jen·ə·rə·rət ′fȯr ‚wāv ′mik·siŋ] (optics) A method of achieving optical phase conjugation in which two strong counterpropagating pump beams, having the same frequency, set up a standing wave in a clear material whose index of refraction varies linearly with intensity, thereby providing the conditions in which a third beam, at the same frequency, incident upon the material from any direction, results in a fourth beam which precisely retraces the third one.