Multiphoton transitions in nonmonochromatic fields and interference in an intermediate state

I. V. Lebedev

C. C. Wang, John V. James, J. F. Xia

C. C. Wang, John V. James, Jinming Xia

M. Ya. Agre, Л. П. Рапопорт

Eduard A. Manykin

Phenomenon of nonlinear interference as a result of no less than two monochromatic light wave with far difference of optical frequencies is discussed by means of the function of correlation for the electrical field amplitude. The extension of the nonlinear interference theory on nonmonochromatic light waves for multiphoton resonances is represented.

Mikhail Vladimirovich Fedorov, A. M. Movsesian

Continuum–continuum, bound–bound, bound–free, and free–bound atomic field-induced transitions are investigated. The initial atomic state is supposed to be given by a wave packet of coherently populated levels of continuous or discrete spectra. Interference effects were found to increase the probabilities of these types of transition and to change their dependence on the pulse duration τ. Interference is shown to occur also in the two-photon ionization probability with highly excited Rydberg levels as intermediate states. Criteria of applicability of the energy diffusion model are formulated. The different diffusion criteria are shown to be incompatible with each other, owing particularly to described interference effects. An alternative picture of multiphoton excitation is suggested. This picture is similar to the above-threshold ionization and predicts the appearance of some maxima in the spectrum of excited electrons below the ionization threshold.