FEATURES OF HIGH-HARMONIC GENERATION BY ATOMS AT SUPERINTENSE AND ULTRASHORT LASER PUMPING

A semiclassical approach for the description of high-harmonic generati on by atoms in a superstrong laser field is developed. Atomic state de pletion is taken into account using the exact (numerical) solution of the Schrodinger equation for an H-atom in the static limit. This solut ion demonstrates an essential decrease of ionization rate growth in su perstrong laser fields. Numerical calculations of high-harmonic genera tion with this approach reveal a new effect: nonmonotonic dependence o f the individual harmonics intensity on the pump intensity in the case of using ultrashort laser pumping.