Four-wave mixing in a ladder configuration of warm 87 Rb atoms: a theoretical study

We present a theoretical study of the four-wave mixing (FWM) spectra of 5 S 1/2 − 5 P 3/2 − 5 D 5/2 ladder-type transitions of 87 Rb atoms. The density matrix equations are solved by considering all the magnetic sublevels to calculate the FWM signals in the atomic vapor cell. These results are subsequently compared with the experimental results. We observe that the FWM signal propagating exactly opposite to the driving field is measured experimentally. Additionally, we demonstrate the effects of optical depth, laser linewidths, and the coupling field power on the FWM spectra. Finally, the origin of the dispersive-like FWM signal is investigated by intentionally varying the intrinsic atomic properties.