Optical phase conjugation by degenerate four-wave mixing: spatial and temporal aspects

We describe an experiment in phase conjugation using holographic degenerate four-wave mixing with picosecond pulses. Spatial and temporal distortions are simultaneously introduced on the probe beam, respectively, by a ground glass and a Gires-Tournois interferometer. We experimentally show that after it recrosses the ground glass we obtain a time reversed pulse on the reconstructed beam. Its temporal shape is the same as that without the ground glass. We theoretically discuss this result and show that in our configuration the temporal effect depends only on the hologram dimension parallel to the direction of propagation of the beam, while the spatial phase conjugation is related to the dimensions in the perpendicular plane.