Electromagnetically induced absorption in Rb atoms with circular polarization of laser beams: Effects of neighboring transitions

We have studied the effects of neighboring transitions on electromagnetically induced absorption (EIA) and electromagnetically induced transparency (EIT) in the D2 transition line in Rb atoms with respect to the same circular polarization configurations ([Formula: see text]) of coupling and probe lasers. Spectra for the open [Formula: see text] transition of (87)Rb and the [Formula: see text] and 3 transitions of (85)Rb exhibit EIA, resulting from the neighboring effect of [Formula: see text] and [Formula: see text] transitions, respectively. In contrast, EIT is observed for the open [Formula: see text] transition of (87)Rb, which indicates greater hyperfine energy splittings of (87)Rb and weaker neighboring effects than those of (85)Rb. Based on the theoretical results, we can confirm that EIT in the case of [Formula: see text] for (87)Rb for the same circular polarization configuration transforms into EIA due to the magnitude of the neighboring effects with a decrease in the hyperfine energy splittings.