Fundamental spectroscopy of dressed-state-polarized atomic samples

The perturbation of atomic spectra by strong resonant optical driving fields can be analyzed to provide fundamental information regarding the physics of light–matter interaction. It is now well known that cw driving fields split the resonance fluorescence spectrum into three components and probe spectra (representing, for example, absorption from one terminal level of a strongly driven transition) into two components. These splittings are conveniently explained in terms of transitions between various eigenstates (dressed states1) of the coupled atom-field system.