Grigory I. Kropotov

Dr. Grigory I. Kropotov

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Academic Career Length

8Years (2019-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 March 2019 in Optics and Spectroscopy
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IKI. A. Kaplunov
I. A. Kaplunov
AKA. I. Kolesnikov
A. I. Kolesnikov
GKGrigory I. Kropotov
Grigory I. Kropotov
VRV. E. Rogalin
V. E. Rogalin
The transmission of intrinsic, antimony-doped, and gallium-doped Ge single crystals in the THz spectral range have been experimentally investigated. It is shown that the attenuation...
21 April 2023 in Journal of Optics
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VBVladimir Bassarab
Vladimir Bassarab
VSVadim A. Shalygin
Vadim A. Shalygin
ASA A Shakhmin
A A Shakhmin
VSV S Sokolov
V S Sokolov
GKGrigory I. Kropotov
Grigory I. Kropotov
We report on the experimental studies of the interaction of electromagnetic radiation with borosilicate crown glass K108 in the ultrawide frequency range from 0.002 to 1500 THz. Four different types of spectrometers are used to measure the reflectivity and/or transmittance spectra. Spectral dependences of the complex dielectric permittivity, refractive index and extinction coefficient are extracted from the measured spectra. The optical properties of the borosilicate crown glass in the microwave spectral range (2–23 GHz) are investigated for the first time. There are three bands of anomalous dispersion in the spectral curve of the real part of the dielectric permittivity. Each band of the anomalous dispersion corresponds to an absorption band, which is clearly seen in the spectrum of the imaginary part of the dielectric permittivity. The wide low-frequency absorption band is attributed to the Boson peak. Two other examined absorption bands represent sharp peaks and are associated with the Si–O–Si bending and Si–O stretching vibration modes. The results of the study can be useful in the development of optics based on the borosilicate crown glass.
10 May 2021 in Applied Physics Letters
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AGAlexander Grebenchukov
Alexander Grebenchukov
VIV. I. Ivanova
V. I. Ivanova
GKGrigory I. Kropotov
Grigory I. Kropotov
MKM. K. Khodzitsky
M. K. Khodzitsky
Faraday rotation effect of magnetized hexagonal ferrites BaAlxFe12−xO19 ( x = 1.4 , 2.0 ) with a varied density in the frequency range of 0.1–1.0 THz was investigated using terahertz (THz) time-domain spectroscopy. Broadband polarization rotation up to 20° for 1-mm thick hexaferrite was demonstrated at room temperature. It was shown that the value of Faraday rotation can be effectively controlled by varying hexaferrite sample density as well as Al concentration. From the experimental data, the full permittivity tensor characterization of different hexaferrite samples was extracted to double-check the calculation of Faraday rotation. The obtained results demonstrate prospects for the utilization of BaAl1.4Fe10.6O19 hexaferrite with the highest density as a broadband self-biased complete THz isolator with moderate insertion losses below 5 cm–1 in the range up to 0.4 THz.
26 October 2021 in IEEE Transactions on Terahertz Science and Technology
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AGAlexander Grebenchukov
Alexander Grebenchukov
VIValentina I. Ivanova
Valentina I. Ivanova
ASAnton Suslov
Anton Suslov
GKGrigory I. Kropotov
Grigory I. Kropotov
MKMikhail K. K. Khodzitsky
Mikhail K. K. Khodzitsky
Breaking reciprocity in optical systems is enabling the possibility of implementing devices with unidirectional wave propagation. Currently, there is an active search for suitable material with an efficient nonreciprocal response at the terahertz (THz) frequency range. Ideally, such material should allow low-loss operation without an external magnetic field at room temperature. Gyrotropic hexaferrite ceramic is highly promising for achieving optical isolation in the THz spectral range. Here, we demonstrate a broadband self-biased THz isolator based on magnetized aluminum-substituted barium hexaferrite. We reveal the necessary surface density of the hexaferrite sample for the realization of THz isolation. The proposed device exhibits no less than 30 dB of isolation from 0.2 to 1 THz. Moreover, we show that the gyrotropy properties of hexaferrite ceramics can be reasonably predicted by their magnetic properties. This device is expected to be useful for applications where one-way propagation of broadband THz wave is desired.
9 September 2024 in Crystals
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GKGrigory I. Kropotov
Grigory I. Kropotov
VRVladimir Efimovich Rogalin
Vladimir Efimovich Rogalin
IKI. Kaplunov
I. Kaplunov
Germanium (Ge) is a system-forming material of IR photonics for the atmospheric transparency window of 8–14 µm. For optics of the 3–5 µm range, more widespread silicon (Si), which has phonon absorption bands in the long-wave region, is predominantly used. A technology for growing Ge single crystals has been developed, allowing the production of precision optical parts up to 500 mm in diameter. Ge is used primarily for the production of transparent optical parts for thermal imaging devices in the 8–14 µm range. In addition, germanium components are widely used in a large number of optical devices where such properties as mechanical strength, good thermal properties, and climatic resistance are required. A very important area of application of germanium is nonlinear optics, primarily acousto-optics. The influence of doping impurities and temperature on the absorption of IR radiation in germanium is considered in detail. The properties of germanium photodetectors are reported, primarily on the effect of photon drag of holes. Optical properties in the THz range are considered. The features of optical properties for all five stable isotopes of germanium are studied. The isotopic shift of absorption bands in the IR region, caused by phonon phenomena, which was discovered by the authors for the first time, is considered.
1 October 2020 in Optics and Spectroscopy
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Journal Article
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IKI. Kaplunov
I. Kaplunov
GKGrigory I. Kropotov
Grigory I. Kropotov
VRVladimir Efimovich Rogalin
Vladimir Efimovich Rogalin
ASA. A. Shakhmin
A. A. Shakhmin
The transmission of THz (to 3000 μm) radiation by alkali halide single crystals of sodium chloride (NaCl), potassium chloride (KCl), potassium bromide (KBr), and rubidium iodide (RbI), which are widely used in the IR spectral region, is studied. The spectral dependences of the absorption coefficients of these materials in the range of 0.9–3000 μm are determined. These materials are transparent in the range of 1000‒3000 μm, which makes it possible to use them in terahertz (millimeter) devices.