Why hyper-Raman lines are absent in high-order harmonic generation

Abstract

The absence of hyper-Raman lines in the observed spectrum emitted by an atom in the presence of a strong laser field is explained by evaluating the spectrum emitted by a unidimensional atom. It is found that the lines are emitted during a short time interval by the atom and that they therefore are small when compared with harmonical lines that are instead emitted during the laser pulse.