Dressing Role in Fourth-Order Fluorescence and Spontaneous Parametric Four-Wave Mixing

For the first time, we report the time-domain asymmetry and discrepancy of spectra of a two-level, V-level, and Λ -level system. Time-domain signal shows asymmetrical dressed splitting. Spectral discrepancy comes from three signals of three different stages that are indicated in the rising edge, top (adiabatic population transfer stage), and descending edge (spontaneous radiation) of the right peak in time domain. It is observed that we can control dressing signals at different stages in right peak by changing power, detuning, polarization, and so on. It is observed that there is a strong dressing in the fluorescence due to the adiabatic population transfer between the dressed states and the very weak dressing in spontaneous parametric four-wave mixing signals for the nonexistence of adiabatic population transfer. This process is well explained theoretically and experimentally using different level systems.