Analytical solutions for a doubly driven two-level atom

We have deduced analytical solutions of an energy level diagram of the doubly driven/dressed atom for a two-level atom exposed to a strong near-resonant bichromatic laser field in a special case, i.e., the bichromatic field with frequencies omega(1) and omega(2), and Rabi frequencies Omega(1) and Omega(2), in which the first coupling field of Omega(1) acts on the bare atomic levels, and then the resulting singly dressed states are driven by the second coupling field of Omega(2), thus resulting in the doubly dressed atom. We have measured the probe absorption spectra of a doubly driven two-level atom. The system consists of 5(2)S(1/2), F = 2 and 5(2)P(3/2), F' = 3 states of Rb-87 atoms in a magneto-optical trap (MOT) as well as the cooling/trapping beams and an additional coupling field. As for the spectroscopic properties of the doubly driven two-level atom, theoretical analytical solutions are in general agreement with the experimental spectrum as a whole.