We experimentally demonstrate spatial interference between simultaneously generated four-wave mixing (FWM) and six-wave mixing (SWM) signals in a multilevel atomic system. By tuning the relative phase between the FWM and SWM processes the relative strengths between these two high-order nonlinear optical processes can be investigated.
Using phase control between four-wave mixing (FWM) and six-wave mixing (SWM) channels in a four-level atomic system, we demonstrate temporal and spatial interferences between these two nonlinear optical processes. Efficient and coexisting FWM and SWM signals are produced in the same electromagnetically induced transparency window via atomic coherence. The temporal interference has a femtosecond time scale corresponding to the optical transition frequency. Such studies of intermixing between different order nonlinear optical processes with a controllable phase delay can have important applications in high-precision measurements, coherence quantum control, and quantum information processing.
We investigate the interplay between six-wave mixing (SWM) and four-wave mixing (FWM) resulting from atomic coherence and polarization beat in a four-level atomic system. The dressed FWM evolution and competition pathways can be controlled by the coupling field to exhibit two FWM and SWM turning points, FWM+SWM, and FWM+FWM interference regions. Quantum interference between two FWM or one FWM and one SWM channels leads to nonlinear signal enhancement and suppression under different conditions. The fifth-order nonlinear response can be obtained by the phase control of the polarization beat between the FWM and SWM signals.
We experimentally demonstrate that four-wave mixing (FWM) and six-wave mixing (SWM) processes can be selectively turned on and off in a close-cycled four-level atomic system. Under certain laser beam configuration, the FWM and SWM processes can be made to coexist with similar signal amplitudes and transmit through the same electromagnetically induced transparency window in such folded four-level atomic system. By introducing an additional pumping laser beam connecting to the fifth energy level, both FWM and SWM signals can be greatly enhanced.
We experimentally investigate the interplay between two coexisting six-wave mixing (SWM) signals and the interference between coexisting four-wave mixing (FWM) and SWM signals in a five-level atomic system of 85 Rb. When two electromagnetically induced transparency windows gradually overlap in frequency, the competition between these two SWM signals arises. Moreover, we report the experimental result which shows that the temporal interference with femtosecond time scales between FWM and SWM signals.
We demonstrate efficient energy exchange during propagation between four-wave-mixing (FWM) and six-wave-mixing (SWM) signals generated in a four-level inverted-Y atomic system, which fall in the electromagnetically induced transparency window. After an initial growth distance for both FWM and SWM fields in the atomic medium, these two nonlinear optical processes compete and exchange energy between them, and eventually reach their respective steady-state values at long interaction distance. This energy exchange phenomenon can be explained by considering established atomic coherences among various atomic states and quantum interferences between three-photon and five-photon excitation pathways. Understanding these high-order nonlinear optical processes and interplays between them can be very important for correlated FWM (or SWM) photon-pair generations and quantum information processing.