Electromagnetically induced two-photon transparency in rubidium atoms

We present an experimental demonstration of electromagnetically induced two-photon transparency (EITT) in room temperature rubidium vapor. The 8S(1/2) to 5P(1/2) fluorescence is used to monitor the 5S(1/2)(F = 3)to 8S(1/2)(F = 3) two-photon absorption near resonance with the intermediate state 5P(3/2). A controlling pump laser beam is employed to coherently couple the 5P(3/2) and 5D(5/2) states, thus producing tw dressed intermediate states which give rise to destructive interference in the two-photon transition. An induced two-photon transparency of about 80% has been obtained at resonance; our experimental findings are in good agreement with the general theory of Agarwal et al. (Phys. Rev. Lett., 77 (1996) 1039), when the appropriate spectroscopic parameters are used.