Angle dependence of quasimonochromatic radiation scattered in a resonant medium

Valerii S. Butylkin, Yury G. Khronopulo, A. E. Kaplan +1 more

Yu. V. Petrushevich, Andrei N Starostin

Numerical modelling is reported of the propagation of laser radiation in a resonant three-level medium. The transient nature and the spatial inhomogeneity of the investigated processes are taken into account. It is shown that the radiation is scattered into narrow cones and that the number and vertex angles of these cones depend on the experimental conditions. The spatiotemporal spectrum of the radiation field emerging from the scattering medium and the dependence of this spectrum on the laser radiation frequency are compared with the results of experiments carried out under similar conditions. The calculated and experimental results are shown to agree under various scattering conditions when the spectral distributions of the scattered-radiation field are qualitatively different.

R. I. Sokolovskiǐ

T. R. Akhmedzhanov, V. A. Antonov, Olga A. Kocharovskaya

We suggest a highly efficient method of ultrashort pulse formation from resonant XUV radiation due to sub-laser-cycle modulation of the excited state of non-hydrogen-like atoms by a nonionizing IR laser field. This modulation results in formation of the Raman-Stokes and anti-Stokes sidebands in coherently forward-scattered radiation, which, in turn, leads to formation of short pulses, when the phases of the sidebands are matched. This method is a generalization of a recently suggested technique [V. A. Antonov et al., Phys. Rev. A 88, 053849 (2013)] for a non-hydrogen-like medium. The possibility to form 2-fs XUV pulses in the gas of helium atoms and 990-as XUV pulses in the plasma of Li+ ions with efficiencies over 80% is shown.

Yu. A. Vdovin, V. M. Ermachenko

Mikhail V. Arkhipov, Rostislav M. Arkhipov, Yu. A. Tolmachev

Specific characteristics of the radiation of a resonant medium excited by an ultrashort light pulse propagating through the medium with a superluminal velocity are considered. The medium is assumed to consist of identical linear harmonic oscillators with a spatial density periodically modulated along the direction of propagation of the superluminal excitation. The field of radiation of the resonant medium under these conditions is calculated. It is shown that, under the superluminal excitation, the radiation spectrum of the medium shows, along with the fundamental frequency of the oscillators, new frequencies that depend on the spatial frequency of the distribution of oscillators and on the angle of observation. Possible application of the effect is discussed.