Probe absorption-dispersion spectra of a driven three-level atom in a double-band photonic crystal

The probe absorption-dispersion spectra of a driven three-level atom in a double-band photonic crystal have been investigated. We use the model which assumes the upper levels of the atomic transitions coupled via a classical driving field. One of the transitions interacts with the free vacuum modes, and the other transition couples to the modes of the modified reservoir (photonic band gap). The effect of the classical driving field on the absorption-dispersion spectra of an atom is investigated in detail. Most interestingly, it is shown that the atom becomes transparent to a probe laser field coupled to the free space transition, and slow group velocities are obtained near the transparency window