Resonant degenerate four-wave mixing spectroscopy of transitions with degenerate energy levels: Saturation and polarization effects

摘要: The physics of the degenerate four-wave mixing process for resonant transitions between two energy levels is investigated by direct numerical integration time-dependent density matrix equations. Zeeman structure upper and lower included in a multistate formulation inclusion enables investigation different polarization configurations forward pump, backward probe beams. Saturation curves lineshapes are calculated numerous low-J transitions. At low laser intensity, results our calculations excellent agreement with perturbation theory terms relative intensities signal linear configurations. As intensity increases resonance starts to saturate, we find general that reflectivity crossed compared parallel configuration because saturation higher. However, some transitions, saturate at than configuration, even though these much perturbative limit. This result explained coupling various states during interaction specific effect on line shapes also investigated. Finally, limited number performed resonances Doppler broadened as well collision broadened. more significant comparable collisional broadening.