GENERATION OF HIGH-ORDER HARMONICS IN A HIGH-INTENSITY LASER-RADIATION FIELD

An analysis is made of the generation of high-order harmonics by atoms and ions in high-intensity laser beams. A brief description is given of the main experimental relationships governing such generation, of m ethods for numerical solution of the Schrodinger equation for an atom in a strong field, and of some approximate models which make it possib le to understand the mechanism of the effect (in particular, the 'semi classical' model). A detailed discussion is made of an analytic quantu m-mechanical theory of high-order harmonic generation in a one-electro n system with the Coulomb, delta-like, and other potentials. Expressio ns are provided for the complex amplitudes of harmonics generated by m onochromatic and bichromatic excitation. The results of simulation of high-order harmonic generation in an extended medium are given. This s imulation takes into account the phases of the harmonics and their dep endences on the amplitude of the fundamental-frequency field. The phas e-matching problem and ways of solving it, the problem of the spectrum and duration of a pulse of a single harmonic and of the feasibility o f controlling them, the problem of the total harmonic field, and other topics are considered.