AC Stark splitting of a three-level system driven by two strong fields

Summary form only given.It is well known that a strongly driven transition exhibits a doublet splitting when probed by a weak field, commonly known as AC Stark splitting. It can be observed either by probing the driven two-level itself (Mollow-type spectrum) or via a third level (Autler-Townes-type spectrum). These two type splittings can have very different characteristics, particularly when driven resonantly. The absorptive Mollow spectrum consists of two dispersion-like features, whereas for the Autler-Townes spectrum there is a simple doublet splitting. In this paper we report the observation of both Mollow and Autler-Townes spectrum simultaneously by applying two strong driving fields in a three-level configuration.