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ALT'23 The 30th International Conference on Advanced Laser Technologies
N-I-4
Coherent radiation generation by atomic systems in intense arbitrarily polarized laser fields
S.Yu. Stremoukhov
Faculty of Physics, Lomonosov Moscow State University, Leninskie Gory, 1 /2, Moscow, 119991, Russia National Research Centre "Kurchatov Institute", Akademika Kurchatova sq. 1,Moscow, 123182, Russia
e-mail: sustrem@gmail.com
High-order harmonic generation (HHG) and generation of terahertz (THz) radiation in matter interacting with intense laser fields are the most actively studied phenomena in non-linear optics. Initially, it was assumed that the mechanisms of HHG and THz radiation are "located" on different spatial scales: HHG is a consequence of the response of a single atom [1], when discussing the mechanisms of generation of THz radiation in gaseous media, one mainly singles out the contributions of the macroscopic photocurrent generated by ionized electrons motion in the laser field, and a neutral medium by taking into account its nonlinear susceptibility tensors [2]. At the same time, experimental studies demonstrate the common features of these two phenomena [3], therefore, at present, the concept of the unified nature of these phenomena is being developed: HHG and THz radiation generation are the result of a common process of electron motion in the superposition field of multicomponent multi-color arbitrarily polarized laser radiation and Coulomb potential of the atom [4, 5].
This work presents the results of recent theoretical studies on HHG and THz radiation by atomic systems interacting with two-color femtosecond laser fields. The calculations were carried out using a non-perturbative theoretical approach [5], which makes it possible to calculate the amplitudes and phases of radiation generated by a single atoms, as well as an interference model [6, 7], which makes it possible to calculate the angular-frequency spectra of radiation generated by an extended medium, which is an ensemble of space-distributed and non-interacting with each other atoms. The contribution of the effects of quasi-phase matching [8] during HHG and THz radiation by media, which are a set of gas jets separated by vacuum gaps, is discussed from the point of view of developing methods for increasing the generation efficiency and controlling the polarization state of the generated radiation.
The work was partially supported by the RFBR under Project No. 19-29-12030.
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