Effects of neighboring transitions on electromagnetically induced absorption and transparency in Rb atoms with circular polarization of laser beams

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 parallel and orthogonal circular polarization configurations (σ⁺ - σ⁺ and σ⁺ - σ^- ) of coupling and probe lasers have been investigated. For the same circular polarization configuration, spectra for the open transitions exhibit EIA or EIT due to neighboring effects depending on hyperfine energy splittings. For the orthogonal polarization configuration the dominance of closed D2 transition results in the observation of asymmetric and split EIA at all of transitions regardless of the openness or closing of the transitions. The spectra of ⁸⁵Rb and ⁸⁷Rb are analyzed by investigating the variation of the spectra of ⁸⁵Rb with an artificial increase of the hyperfine splittings and accordingly with the decreasing of the neighboring effects. This leads to the difference in the absorption profiles of the two isotopes.