Abstract

We present theoretical investigation of the carrier-wave Rabi flopping phenomenon (CWRF) in real atoms by employing numerical simulations of high-order harmonic generation (HHG) in alkali species [1]. Given the short HHG cutoff, closely related to the low saturation intensity of the targets, we concentrate on the features of the third harmonic of sodium (Na) and potassium (K) atoms. For pulse areas of 2π and Na atoms, a unique peak appears, which, after analyzing the ground state population, we correlate it with the conventional Rabi flopping. On the other hand, for larger pulse areas, CWRF occurs, and emerges as a more complex structure in the third harmonic. This new feature is identified with rapid changes in the ground state population, in a time scale much shorter than the conventional one. The new characteristics observed in K atoms indicate the breakdown of the area theorem, as was already demonstrated under similar circumstances in narrow band gap semiconductors [2].

© 2015 IEEE