Publications by authors named "Alexander Ushakov"

For the first time to our knowledge, multiwavelength, highly transient, single-pass stimulated Raman scattering with a low wavelength spacing on dual (stretching and bending) Raman modes in Sr(MoO)(WO) and Sr(MoO)(WO) solid solutions in a range of 1000-1300 nm (transparence window of biological tissue) under ultrafast chirped pulse laser pumping is comparatively investigated in the interests of multicolor two-photon imaging of a living tissue. For both the solid solutions, the optimum range (1-5 ps) of chirped pump pulse durations for multiwavelength Raman conversion on dual Raman modes was wider than for SrMoO (2-3 ps) due to the higher integral cross section of the bending Raman mode. Higher efficient SRS conversion took place at negative chirping of the pump pulse with its stretching from 0.

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Diamond is a promising material for terahertz applications. In this work, we use a non-invasive optical pump-terahertz probe method to experimentally study the photoinduced carrier dynamics in doped diamond monocrystals and a new diamond-silicon composite. The chemical vapor deposited diamond substrate with embedded silicon microparticles showed two photoinduced carrier lifetimes (short lifetime on the order of 4 ps and long lifetime on the order of 200 ps).

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The generation of terahertz radiation in a photoconductive emitter based on nitrogen-doped single-crystal diamond was realized for the first time. Under 400 nm femtosecond laser pumping, the performance of diamond antennas with different dopant levels was investigated and compared with a reference ZnSe antenna. Terahertz waveforms and corresponding spectra were measured.

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Forward stimulated Raman scattering (SRS) induced by focused 400 nm pulses chirped to different pulse durations is observed in water and heavy water. The first Stokes Raman peak shift is shown to be tunable in the range of ${{3500 {-} 4200}}\;{{\rm{cm}}^{- 1}}$ in water and ${{2450 {-} 3250}}\;{{\rm{cm}}^{- 1}}$ in heavy water. It is demonstrated that the Stokes peak shift increases for shorter pulse durations and higher intensities.

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Hybrid organic-inorganic perovskites, while well examined for photovoltaic applications, remain almost completely unexplored in the terahertz (THz) range. These low-cost hybrid materials are extremely attractive for THz applications because their optoelectronic properties can be chemically engineered with relative ease. Here, we experimentally demonstrate the first attempt to apply solution-processed polycrystalline films of hybrid perovskites for the development of photoconductive terahertz emitters.

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Aim: Modern methods of producing poultry meat without the use of antibiotics are known, and it is possible to achieve the desired conditions, including the use of herbal preparations. In addition, it is known that metabolites of medicinal plants are inhibitors of the quorum sensing system in bacteria. The aim of the present study was to determine the effect of extract in a reduced dose on the productivity and body state of healthy chicken broilers.

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