Dual-frequency phase conjugation wave generation with the high-order nonlinear effect by nondegenerate six-wave mixing in photorefractive Fe:LiNbO(3).

This paper demonstrates dual-frequency phase conjugation waves via the high-order nonlinear effect by nondegenerate six-wave mixing in iron-doped lithium niobate. In the experiment, two conjugation waves of different frequency are generated. Conjugation wave 1 is similar to nondegenerate four-wave mixing; conjugation wave 2 is completely different. The experiments measure the relationships between two conjugation wave intensities and parameters, respectively, and compare the differences of the two conjugation waves. To explain the experimental results, we assume that there is a fifth-order nonlinear interaction in crystal, and we believe the two conjugation waves are generated via different level nonlinear interactions. The theory agrees with the experimental results.