High Intensity Effects in Raman Scattering

Przemyslaw Szlachetka, S. Kielich, Jan Peřina +1 more

I. P. Prokopovich, A. A. Khrutchinsky

The dynamics of high-intense laser fields at coherent Raman self-scattering are investigated by the use of numerical simulation. The processes under investigation take place at the Raman scattering on electronic states in atoms with transition to be forbidden in electro-dipole approximation, on vibrational or rotational states in molecules, on states connected with the spin flip and other. It is found that the threshold intensities exist provided that the pulse duration is smaller than dephasing time of the Raman transition in the medium. Under this, the following processes occur: an effective generation of the high-order harmonics comes up; the plateau forms in the harmonic spectrum. The maximum which arises on this plateau shifts to the higher-harmonic numbers in case of the higher threshold intensities of the pulse. It is shown how the transformation of the initial pulse intensity into high-order harmonics intensity can be considerably increased with the different initial parameters of the pulse and the medium.

M. M. Suchchinskii

Claude N. Cohen-Tannoudji, Serge Reynaud

The general method developed in a previous paper (see ibid., vol.10, p.345 (1977)) is applied to the problem of resonance Raman scattering in very intense laser fields. At very low intensities the spectrum consists of three monochromatic lines (Rayleigh, Raman Stokes and anti-Stokes) which split into a triplet and two doublets when the laser light, tuned on one of the two transitions connecting the upper state to the two lower sublevels, has a sufficiently high intensity to saturate this transition but not the second one. The Raman and Rayleigh lines are completely mixed when the intensity becomes so high that both transitions are saturated. The corresponding evolution of the spectrum is determined. Optical-pumping effects leading to asymmetries in the fluorescence spectrum are taken into account.

Guang S. He

When a high-intensity laser beam passes through a transparent and homogeneous optical medium, the induced light scattering may manifest the properties of stimulated radiation characterized by threshold requirement, high directionality, and high brightness. This is the stimulated scattering of intense coherent light. Discoveries and studies of various types of stimulated scattering effects have provided a much deeper and more comprehensive understanding of interactions between the intense coherent light and matter. On the other hand, devices based on stimulated Raman scattering, stimulated Brillouin scattering, and stimulated spin-flip Raman scattering can be employed as highly efficient tunable frequency shifters of coherent light. Stimulated Kerr scattering can be used to generate a super-broadband coherent light and to investigate the molecular anisotropy of liquids. In addition, the recently developed stimulated Rayleigh–Bragg scattering and stimulated Mie scattering can significantly reduce the threshold requirement, and provide a highly efficient no-frequency-shift optical phase conjugation wave.

Chin‐Kun Hu, Cheng‐Liang Huang