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Кондратьев, Кирилл Александрович

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Институт лазерных и плазменных технологий
Стратегическая цель Института ЛаПлаз – стать ведущей научной школой и ядром развития инноваций по лазерным, плазменным, радиационным и ускорительным технологиям, с уникальными образовательными программами, востребованными на российском и мировом рынке образовательных услуг.
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Кондратьев
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Кирилл Александрович
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2020 - 20223
21
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    Propagation and Depolarization of a Short Pulse of Light in Sea Water
    (2020) Gorodnichev, E. E.; Kondratiev, K. A.; Kuzovlev, A. I.; Rogozkin, D. B.; Городничев, Евгений Евгеньевич; Кондратьев, Кирилл Александрович; Кузовлев, Александр Иванович; Рогозкин, Дмитрий Борисович
    We present the results of a theoretical study of underwater pulse propagation. The vector radiative transfer equation (VRTE) underlies our calculations of the main characteristics of the scattered light field in the pulse. Under the assumption of highly forward scattering in seawater, three separate equations for the basic modes are derived from the exact VRTE. These three equations are further solved both within the small-angle approximation and numerically. The equation for the intensity is analyzed for a power-law parametrization of the wings of the sea water phase function. The distribution of early arrival photons in the pulse, including the peak intensity, is calculated. Simple relations are also presented for the variance of the angular distribution of radiation, the effective duration of the signal and other parameters of the pulse. For linearly and circularly polarized pulses, the temporal profile of the degree of polarization is calculated for actual data on the scattering matrix elements. The degree of polarization is shown to be described by the self-similar dependence on some combination of the transport scattering coefficient, the temporal delay and the source-receiver distance. Our results are in agreement with experimental and Monte-Carlo simulation data. The conclusions of the paper offer a theoretical groundwork for application to underwater imaging, communication and remote sensing.
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    Enhancement of mesoscopic fluctuations in transmission of light through a disordered medium at grazing angles
    (2021) Sheberstov, S. V.; Kondrat'ev, K. A.; Marinyuk, V. V.; Rogozkin, D. B.; Кондратьев, Кирилл Александрович; Маринюк, Виталий Владиславович; Рогозкин, Дмитрий Борисович
    © 2021 American Physical Society.We study how intensity fluctuations in transmission through a disordered slab change depending on the regime of wave transport. A system with large (compared to the wavelength of light) inhomogeneities is considered. Within a diagrammatic approach, the variance of the total transmission coefficient is calculated numerically beyond the diffusion approximation. A great enhancement of fluctuations is found in the crossover from the ballistic to the diffusive transport at the grazing angles of incidence on the sample surface. The effect originates from the reflection of waves that propagate nearly parallel to the sample boundaries and experience scattering through small angles, and reveals itself both in transmission and reflection and in correlations between the transmitted and reflected fluxes.
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    Coherent backscattering of light from a Faraday medium
    (2022) Gorodnichev, E. E.; Kondratiev, K. A.; Rogozkin, D. B.; Городничев, Евгений Евгеньевич; Кондратьев, Кирилл Александрович; Рогозкин, Дмитрий Борисович
    © 2022 American Physical Society.We study coherent backscattering (CBS) of light from a magnetoactive medium doped by Mie particles. A novel version of the CBS diffusion theory is developed, which takes into account both the Faraday effect and the effect of circular polarization memory specific to Mie scattering. The theory is based on a system of coupled diffusion equations for two slowly decaying cooperon modes arising from interference of waves with coinciding helicities. The impact of a magnetic field on CBS is shown to be controlled by the ratio of the helicity-flip scattering cross section to the transport scattering one. If this ratio is small, the CBS can exhibit unusual features first found experimentally by R. Lenke, R. Lehner, and G. Maret [Europhys. Lett. 52, 620 (2000)EULEEJ0295-507510.1209/epl/i2000-00483-y]. In the magnetic field parallel to the sample surface, the peak of coherent backscattering for circularly polarized light is shifted from the exact backward direction, while, for linearly polarized light, it splits in two ones for both co- and cross-polarization channels, and the backscattered waves acquire circular polarization. Saturation of the magnetic field dependence of the CBS cone occurs in the magnetic field normal to the surface. If the above ratio is close to unity (Rayleigh scattering) all these features disappear, and the effect of the magnetic field on the CBS angular profile is reduced to the universal law studied previously. The results obtained are in good quantitative agreement with the available Monte Carlo simulation and experimental data.