Spontaneous and induced emission of high-order harmonics during the above-threshold ionization of atoms

Expressions for the probability of the spontaneous and induced emission of high-order harmonics when the emitter phases are synchronized and are obtained in the region where the multiphoton approximation is applicable to the description of the ionization of an atom (where the adiabaticity parameter satisfies γ > or approx. 1). The dependence of these probabilities on the main parameters of the pump wave and the atomic medium is established. Criteria for observing emission are formulated with the consideration of phase locking. The possibility of amplifying a UV probe wave aimed through the region where the atoms interact with the pump wave is considered