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Author Gol'tsman, Gregory; Semenov, Alexei; Smirnov, Konstantin; Voronov, Boris
Title Background limited quantum superconducting detector for submillimeter wavelengths Type Conference Article
Year 2001 Publication Proc. 12th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 12th Int. Symp. Space Terahertz Technol.
Volume Issue Pages 469-475
Keywords (down) Ti SQD, SQUID readout
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Notes Approved no
Call Number Serial 1540
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Author Nikoghosyan, A. S.; Martirosyan, R. M.; Hakhoumian, A. A.; Makaryan, A. H.; Tadevosyan, V. R.; Goltsman, G. N.; Antipov, S. V.
Title Effect of absorption on the efficiency of THz radiation generation in a nonlinear crystal placed into a waveguide Type Journal Article
Year 2018 Publication Armenian J. Phys. Abbreviated Journal Armenian J. Phys.
Volume 11 Issue 4 Pages 257-262
Keywords (down) THz, waveguide, nonlinear crystal
Abstract The effect of THz radiation absorption on the efficiency of generation of coherent THz radiation in a nonlinear optical crystal placed into a metal rectangular waveguide is studied. The efficiency of the nonlinear conversion of optical laser radiation to the THz band is also a function of the phase-matching (PM) condition inside the nonlinear crystal. The method of partial filling of a metal waveguide with a nonlinear optical crystal is used to ensure phase matching. Phase matching was obtained by the proper choice of the thickness of the nonlinear crystal, namely the degree of partial filling of the waveguide. We have studied the THz radiation attenuation caused by the losses in both the metal walls of the waveguide and in the crystal, taking into account the dimension of the cross section of the waveguide, the degree of partial filling and its dielectric constant.
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ISSN 1829-1171 ISBN Medium
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Notes Approved no
Call Number Serial 1291
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Author Bandurin, D. A.; Svintsov, D.; Gayduchenko, I.; Xu, S. G.; Principi, A.; Moskotin, M.; Tretyakov, I.; Yagodkin, D.; Zhukov, S.; Taniguchi, T.; Watanabe, K.; Grigorieva, I. V.; Polini, M.; Goltsman, G. N.; Geim, A. K.; Fedorov, G.
Title Resonant terahertz detection using graphene plasmons Type Journal Article
Year 2018 Publication Nat. Commun. Abbreviated Journal Nat. Commun.
Volume 9 Issue Pages 5392 (1 to 8)
Keywords (down) THz, graphene plasmons
Abstract Plasmons, collective oscillations of electron systems, can efficiently couple light and electric current, and thus can be used to create sub-wavelength photodetectors, radiation mixers, and on-chip spectrometers. Despite considerable effort, it has proven challenging to implement plasmonic devices operating at terahertz frequencies. The material capable to meet this challenge is graphene as it supports long-lived electrically tunable plasmons. Here we demonstrate plasmon-assisted resonant detection of terahertz radiation by antenna-coupled graphene transistors that act as both plasmonic Fabry-Perot cavities and rectifying elements. By varying the plasmon velocity using gate voltage, we tune our detectors between multiple resonant modes and exploit this functionality to measure plasmon wavelength and lifetime in bilayer graphene as well as to probe collective modes in its moire minibands. Our devices offer a convenient tool for further plasmonic research that is often exceedingly difficult under non-ambient conditions (e.g. cryogenic temperatures) and promise a viable route for various photonic applications.
Address Physics Department, Moscow State University of Education (MSPU), Moscow, Russian Federation, 119435. fedorov.ge@mipt.ru
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ISSN 2041-1723 ISBN Medium
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Notes Approved no
Call Number Serial 1148
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Author Gorokhov, G.; Bychanok, D.; Gayduchenko, I.; Rogov, Y.; Zhukova, E.; Zhukov, S.; Kadyrov, L.; Fedorov, G.; Ivanov, E.; Kotsilkova, R.; Macutkevic, J.; Kuzhir, P.
Title THz spectroscopy as a versatile tool for filler distribution diagnostics in polymer nanocomposites Type Journal Article
Year 2020 Publication Polymers (Basel) Abbreviated Journal Polymers (Basel)
Volume 12 Issue 12 Pages 3037 (1 to 14)
Keywords (down) THz spectroscopy; nanocomposites, percolation threshold, time-domain spectroscopy, time-domain spectrometer, TDS
Abstract Polymer composites containing nanocarbon fillers are under intensive investigation worldwide due to their remarkable electromagnetic properties distinguished not only by components as such, but the distribution and interaction of the fillers inside the polymer matrix. The theory herein reveals that a particular effect connected with the homogeneity of a composite manifests itself in the terahertz range. Transmission time-domain terahertz spectroscopy was applied to the investigation of nanocomposites obtained by co-extrusion of PLA polymer with additions of graphene nanoplatelets and multi-walled carbon nanotubes. The THz peak of permittivity's imaginary part predicted by the applied model was experimentally shown for GNP-containing composites both below and above the percolation threshold. The physical nature of the peak was explained by the impact on filler particles excluded from the percolation network due to the peculiarities of filler distribution. Terahertz spectroscopy as a versatile instrument of filler distribution diagnostics is discussed.
Address Institute of Photonics, University of Eastern Finland, Yliopistokatu 7, FI-80101 Joensuu, Finland
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Language English Summary Language Original Title
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ISSN 2073-4360 ISBN Medium
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Notes PMID:33353036; PMCID:PMC7767186 Approved no
Call Number Serial 1780
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Author Neroev, V. V.; Iomdina, E. N.; Khandzhyan, A. T.; Khodzhabekyan, N. V.; Sengaeva, M. D.; Ivanova, A. V.; Seliverstov, S. V.; Teplyakova, K. O.; Goltsman, G. N.
Title Experimental study of the effect of corneal hydration and its biomechanical properties on the results of photorefractive keratectomy Type Journal Article
Year 2021 Publication Vestn. Oftalmol. Abbreviated Journal Vestn. Oftalmol.
Volume 137 Issue 3 Pages 68-75
Keywords (down) THz scanning, cornea, photorefractive keratectomy, medicine
Abstract Water content in the cornea may affect the outcome of its excimer laser ablation, especially in presbyopic patients with myopic refraction. This hypothesis can be tested by scanning the cornea in the terahertz (THz) range to determine its hydration level.

Purpose: To study the effect of hydration of the cornea determined by non-contact THz scanning and its biomechanical parameters on the results of photorefractive keratectomy (PRK) in an experiment.

Material and methods: PRK was performed using the Nidek EC-5000 QUEST excimer laser on 8 rabbit eyes. Corneal hydration was evaluated by determining the reflection coefficient (RC) in the THz electromagnetic radiation range before PRK, after 3-5 days, and after 1, 2, 3, and 4 months. Clinical examination included autorefractometry, assessment of corneal thickness and other anatomical and optical parameters of the anterior eye segment (Galilei G6, Ziemer Ophthalmic Systems AG 6.0.2, Switzerland), measurement of corneal hysteresis (CH) and corneal resistance factor (CRF) using the Ocular Response Analyzer (ORA; Reichert, USA), as well as tear production (Schirmer test).

Results: The initial water content in the cornea has a significant effect on the thickness of the removed layer, i.e. on the PRK effect, with correlation coefficient of Rs= -0.976 (p<0.01). The correlation between CH and the ablation depth is less pronounced (Rs=0.643), and CRF had no correlation with it (Rs= -0.089). Biomechanical indicators of the cornea depend on its hydration: changes in CH and CRF after excimer laser ablation qualitatively coincide with changes in RC, the correlation coefficient between RC and the initial value of CH is R= -0.619 (moderate negative correlation).

Conclusion: THz scanning is an effective non-contact technology for monitoring corneal hydration level. The mismatch of the hypoeffect of keratorefractive excimer laser intervention planned for patients with presbyopia with the actual outcome can be caused by individual decrease in the initial water content in the cornea.
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Language Russian Summary Language Original Title
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Notes Approved no
Call Number Serial 1794
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