Multi-Wave Mixing Processes in Multi-level Atomic System

Abstract

Since real atomic systems have multiple Zeeman sublevels, one can use polarization states of the coupled laser beams to modulate the strength of the multi-wave mixing processes. By manipulating the dark-state or electromagnetically induced transparency (EIT) windows with the polarization states of the laser beams, the multi-wave mixing (MWM) processes can be modified and controlled. Such studies of controllable intermixing between differentorder nonlinear optical processes with phase or polarization states of the laver beams can be very important in high-precision measurements, coherent quantum control, and quantum information processing. In the following, some examples of phase or polarization controlled multi-wave mixing processes in multi-level atomic systems will be described. The degenerate Zeeman sublevels and their dressed-state effects are responsible for these observed phenomena. The relative intensities and polarization characteristics of fourwave mixing (FWM) signals in different laser polarization configurations and different level systems are experimentally investigated and compared. Also the results are theoretically explained by different transition path combinations. In the dressed-FWM processes, the dependence of dressing effect on the incident field’s polarization is shown. The FWM signal generated by a linearly-polarized pumping field is suppressed more by the dressing field than the one generated by a circularly-polarized pumping field. However, an opposite effect was observed when the probe field’s polarization is changed.