Two-Photon Atomic Coherence Effect of Transition 5S1/2-5P3/2-4D5/2(4D3/2) of 85Rb atoms

We experimentally observe the counterintuitive absorption peaks in the transition spectra of 5S(1/2)-5P(3/2)-4D(5/2) and 5S(1/2)-5P(3/2)-4D(3/2) in a hot Rb-85 vapor. These spectra are very different from the spectra observed via double resonance optical pumping or electromagnetically induced transparency in the same transitions. These absorption peaks are from electromagnetically induced absorption due to the two-photon atomic coherence effect. We also investigate the relations between these peaks and the powers of the coupling laser and the probe laser experimentally.