The Autler-Townes satellites or AC Stark splitting

The two satellites on either side of the main transition are called an Autler-Townes doublet after the names of those who first observed them [473], They were, however, predicted at an earlier date by Mollow [474]. An elegant method of calculating the fluorescence profile was described by Cohen-Tannoudji and Avan [475]. A very full discussion of how to represent this problem, including the central elastic component, the inelastic contributions and the sidebands, can be found in lecture notes by Co hen-Tannoudji [476] 

The AC Stark effect is relevant, not only in atomic spectroscopy, but also in solid state physics. The biexciton state (or excitonic molecule), where two Wannier excitons are bound by the exchange interaction between electrons, occurs in various semiconductors (see section 2.22). Various experiments on the AC Stark effect of excitons have been reported, but the clearest example to date is probably the observation of the Rabi splitting of the biexciton line in CuC reported by Shimano and Kuwata-Gonokami [477]. It is very interesting to consider how Bloch states in solids, which themselves are delocalised and periodic, are dressed or modified by the electromagnetic field, since their properties are rather different from those of purely atomic states, which are by definition completely localised. 

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