Electromagnetically induced absorption due to transfer of coherence and coherence population oscillation for the Fg=3→Fe=4Fg=3→Fe=4 transition in 85Rb atoms

• We present a study of electromagnetically induced absorption for 85Rb atoms.
• We study lineshapes for four polarization schemes of coupling and probe beams.
• The experimental results are compared with calculated results.

Lineshapes for the electromagnetically induced absorption (EIA) of thermal 85Rb atoms in a degenerate two-level system have been investigated using matching (σ∥σ,π∥πσ∥σ,π∥π) and orthogonal (σ⊥σ,π⊥πσ⊥σ,π⊥π) polarization configurations of coupling and probe beams. EIA signals, which result from coherence population oscillation and transfer of coherence of the excited state, are obtained in detail theoretically and experimentally. The observed EIA linewidths, which are limited due to the decoherence rate between the magnetic sublevels in the ground state from transit-time relaxation, match well with the calculated ones. Decompositions of the absorption signals analyzed with respect to magnetic sublevels of the ground state show that enhanced or decreased absorption signals for each component of magnetic sublevels in the ground state depend on several factors. These factors include the decay rates and transition strengths, which determine the overall absorption spectral profile.