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Iomdina, E. N.; Seliverstov, S. V.; Sianosyan, A. A.; Teplyakova, K. O.; Rusova, A. A.; Goltsman, G. N. |
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Terahertz scanning for evaluation of corneal and scleral hydration |
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2018 |
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Sovremennye tehnologii v medicine |
Abbreviated Journal |
STM |
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10 |
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4 |
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143-149 |
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Keywords |
BWO; Golay cell; medicine; cornea; sclera; THz radiation; corneal hydration; backward-wave oscillator; avalanche transit-time diode; IMPATT diode |
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Abstract |
The aim of the investigation was to study the prospects of using continuous THz scanning of the cornea and the sclera to determine water concentration in these tissues and on the basis of the obtained data to develop the experimental installation for monitoring corneal and scleral hydration degree.Materials and Methods. To evaluate corneal and scleral transmittance and reflectance spectra in the THz range, the developed experimental installations were used to study 3 rabbit corneas and 3 scleras, 2 whole rabbit eyes, and 3 human scleras. Besides, two rabbit eyes were studied in vivo prior to keratorefractive surgery as well as 10 and 21 days following the surgery (LASIK).Results. There have been created novel experimental installations enabling in vitro evaluation of frequency dependence of corneal and scleral transmittance coefficients and reflectance coefficients on water percentage in the THz range. Decrease in corneal water content by 1% was found to lead to reliably established decrease in the reflected signal by 13%. The reflectance spectrum of the whole rabbit eye was measured in the range of 0.13–0.32 THz. The study revealed the differences between the indices of rabbit cornea and sclera, as well as rabbit and human sclera. There was developed a laboratory model of the installation for in vivo evaluation of corneal and scleral hydration using THz radiation.Conclusion. The preliminary findings show that the proposed technique based on the use of continuous THz radiation can be employed to create a device for noninvasive control of corneal and scleral hydration. |
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1315 |
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Fedorov, G.; Gayduchenko, I.; Titova, N.; Gazaliev, A.; Moskotin, M.; Kaurova, N.; Voronov, B.; Goltsman, G. |
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Carbon nanotube based schottky diodes as uncooled terahertz radiation detectors |
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Journal Article |
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2018 |
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Phys. Status Solidi B |
Abbreviated Journal |
Phys. Status Solidi B |
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255 |
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1 |
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1700227 (1 to 6) |
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carbon nanotube schottky diodes, CNT |
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Despite the intensive development of the terahertz technologies in the last decade, there is still a shortage of efficient room‐temperature radiation detectors. Carbon nanotubes (CNTs) are considered as a very promising material possessing many of the features peculiar for graphene (suppression of backscattering, high mobility, etc.) combined with a bandgap in the carrier spectrum. In this paper, we investigate the possibility to incorporate individual CNTs into devices that are similar to Schottky diodes. The latter is currently used to detect radiation with a frequency up to 50 GHz. We report results obtained with semiconducting (bandgap of about 0.5 eV) and quasi‐metallic (bandgap of few meV) single‐walled carbon nanotubes (SWNTs). Semiconducting CNTs show better performance up to 300 GHz with responsivity up to 100 V W−1, while quasi‐metallic CNTs are shown to operate up to 2.5 THz. |
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0370-1972 |
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1321 |
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Seliverstov, S. V.; Anfertyev, V. A.; Tretyakov, I. V.; Ozheredov, I. A.; Solyankin, P. M.; Revin, L. S.; Vaks, V. L.; Rusova, A. A.; Goltsman, G. N.; Shkurinov, A. P. |
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Terahertz heterodyne receiver with an electron-heating mixer and a heterodyne based on the quantum-cascade laser |
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2017 |
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Radiophys. Quant. Electron. |
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Radiophys. Quant. Electron. |
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60 |
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7 |
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518-524 |
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NbN HEB mixer, QCL |
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We study characteristics of the laboratory prototype of a terahertz heterodyne receiver with an electron-heating mixer and a heterodyne based on the quantum-cascade laser. The results obtained demonstrate the possibility to use this receiver as a basis for creation of a high-sensitivity terahertz spectrometer, which can be used in many basic and practical applications. A significant advantage of this receiver will be the possibility of placing the mixer and heterodyne in the same cryostat, which will reduce the device dimensions considerably. The obtained experimental results are analyzed, and methods of optimizing the parameters of the receiver are proposed. |
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0033-8443 |
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1322 |
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Trifonov, A.; Tong, C.-Y. E.; Grimes, P.; Lobanov, Y.; Kaurova, N.; Blundell, R.; Goltsman, G. |
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Development of a silicon membrane-based multipixel hot electron bolometer receiver |
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2017 |
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IEEE Trans. Appl. Supercond. |
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IEEE Trans. Appl. Supercond. |
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27 |
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4 |
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1-5 |
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Multi-pixel, NbN HEB, silicon-on-insulator, horn array |
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We report on the development of a multipixel hot electron bolometer (HEB) receiver fabricated using silicon membrane technology. The receiver comprises a 2 × 2 array of four HEB mixers, fabricated on a single chip. The HEB mixer chip is based on a superconducting NbN thin-film deposited on top of the silicon-on-insulator (SOI) substrate. The thicknesses of the device layer and handling layer of the SOI substrate are 20 and 300 μm, respectively. The thickness of the device layer is chosen such that it corresponds to a quarter-wave in silicon at 1.35 THz. The HEB mixer is integrated with a bow-tie antenna structure, in turn designed for coupling to a circular waveguide, fed by a monolithic drilled smooth-walled horn array. |
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1051-8223 |
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1324 |
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Korneeva, Y.; Florya, I.; Vdovichev, S.; Moshkova, M.; Simonov, N.; Kaurova, N.; Korneev, A.; Goltsman, G. |
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Comparison of hot spot formation in nbn and mon thin superconducting films after photon absorption |
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2017 |
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IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
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27 |
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4 |
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1-4 |
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MoNx SSPD |
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In superconducting single-photon detectors (SSPD), the efficiency of local suppression of superconductivity and hotspot formation is controlled by diffusivity and electron-phonon interaction time. Here, we selected a material, 3.6-nm-thick MoNx film, which features diffusivity close to those of NbN traditionally used for SSPD fabrication, but with electron-phonon interaction time an order of magnitude larger. In MoN ∞ detectors, we study the dependence of detection efficiency on bias current, photon energy, and strip width, and compare it with NbN SSPD. We observe nonlinear current-energy dependence in MoNx SSPD and more pronounced plateaus in dependences of detection efficiency on bias current, which we attribute to longer electron-phonon interaction time. |
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1051-8223 |
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1325 |
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