Simultaneous control of two four-wave-mixing fields via atomic spin coherence

We report the experimental observation of simultaneous control of two four-wave-mixing fields via an induced atomic spin coherence formed by a Raman process with one coupling field and one probe field in a triple-Λ-type Rb85 atomic system. It is shown that by changing the atomic density, intensity, or detuning of the coupling field, the relative intensities of the two four-wave-mixing fields can be manipulated. This behavior can be explained as the change in the spin coherence for varying the coupling field intensity and the large difference in the attenuation coefficients of the two produced four-wave-mixing fields for varying the atomic density. This controlling process may find applications in coherent control of nonlinear optical processes and quantum information processing.