Quasienergy spectrum of a two-level atom in the field of high-intensity modulated radiation

An asymptotic method is proposed for the determination of quasienergy levels of an atom in the field of modulated optical radiation. A comparison of the asymptotic and exact solutions is used to show that the range of validity of the new method is considerably wider than those of the known asymptotic methods. An analysis is made of the shifts of the quasienergy levels of an atom under the influence of bichromatic radiation and of a periodic pulse sequence. A modulation method is proposed for the attainment of Doppler-free resonances in gases.