Competition and Energy Transfer Between Forward and Backward Four-Wave Mixing via Atomic Coherence

Two four-wave mixing (FWM) processes with different directions and frequencies can coexist and interfere in a four-level inverted-Y-type atomic system, the generated FWM beams fall into two different electromagnetically induced transparency windows. We report Autler–Townes splitting and dressed suppression and enhancement of two generated FWM beams. In the case of matched slow FWM beams, two FWM processes compete and exchange their energies between them, the forward four-wave beam give its energy to the backward four-wave beam by interaction for long distance. Such studies of two FWM beams can have vital applications in studying the higher-order nonlinear optical processes, generating correlated photon pairs and quantum information processing.