Journal of the Optical Society of America B
Subharmonic resonances in terms of multiphoton processes and generalized Bloch–Siegert shifts
Wilhelmus M. Ruyten
Abstract
In a recent publication [ J. Opt. Soc. Am. B5, 2015 ( 1988)], Chakmakjian et al. gave an empirical expression for the positions of subharmonic resonances of a two-level system driven by a fully amplitude modulated laser. Here we calculate exact positions of the resonances and adapt a dressed-atom analysis from the corresponding magnetic resonance problem. Thus subharmonic resonances are explained as the limiting behavior of multiphoton resonances, and, in the limit of vanishing damping, the positions of the resonances are given by analytical expressions for the generalized Bloch–Siegert shifts.