Action of laser radiation on multilevel systems of the band type

V. M. Akulin, Александр Михайлович Дыхне

V. A. Rantsevich, Nikolai N. Rogovtsov, В. А. Савва

Alexander A. Makarov

G.L. Peterson, Cyrus D. Cantrell, Ronald S. Burkey

É. M. Belenov, Isakov Va, A. Nazarkin

Some features of the excitation of multilevel quantum systems under the action of electromagnetic pulses which are shorter than the inverse frequency of interlevel transitions are considered. It is shown that the interaction is characterized by a specific type of selectivity which is not connected with the resonant absorption of radiation. The simplest three-level model displays the inverse population of upper levels. The effect of an ultrashort laser pulse on a multilevel molecule was regarded as an instant reception of the oscillation velocity by the oscillator and this approach showed an effective excitation and dissociation of the molecule. The estimations testify to the fact that these effects can be observed using modern femtosecond lasers.

N. A. Zharova, Alexander G. Litvak, Vyacheslav A. Mironov

The laser-radiation self-action dynamics in the electromagnetically induced transparency band were studied analytically and numerically for an atomic gas with the Λ-type energy-level scheme. The self-consistent system of equations describing the spatiotemporal evolution of a finite-amplitude wave packet in the field of a uniform pump wave was derived. The self-action in the presence of competing diffraction, nonlinear dispersion, and radiation absorption in the system was qualitatively analyzed; in particular, the conditions for self-focusing of a probe beam were determined. The results were confirmed by the numerical simulation of wave-packet spatiotemporal evolution.