A multilevel -type system of 87Rb, 23Na and 7Li under consideration
Figure 1. A multilevel -type system of 87Rb, 23Na and 7Li under consideration. In the six-level model, , are the ground levels and |e1〉, |e2〉, |e3〉,|es〉 are the excited states. The four-level approximation involves levels , , |e1〉 and |es〉 only. In this figure, only the considered mF values are shown.
We present a six-level atomic system using a density matrix approach to show variation of the optical properties in an -type Doppler-broadened system for the D2 line of alkali atoms with the nuclear spin I = 3/2, i.e. 87Rb, 23Na and 7Li. The variation in optical properties arises due to the presence of multiple excited states with varying separations. These excited states cause asymmetry in absorption profiles. This asymmetric nature is more prominent for an atom with more closely spaced hyperfine levels in the excited state. In room temperature atomic vapour, the enhanced absorption at the line centre starts to disappear with a decrease in hyperfine separation. We also discuss the transient behaviour of considered atoms, which is in good agreement with an absorption profile in each case. This approach opens a possibility of realizing the optical switching application in a realistic atom.