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Author Varyukhin, S. V.; Zakharov, A. A.; Gershenzon, E. M.; Gol'tsman, G. N.; Ptitsina, N. G.; Chulkova, G. M.
Title Low energy excitation in La2CuO4 Type Journal Article
Year 1990 Publication Sverkhprovodimost': Fizika, Khimiya, Tekhnika Abbreviated Journal Sverkhprovodimost': Fizika, Khimiya, Tekhnika
Volume 3 Issue 5 Pages 832-837
Keywords (up) metal-dielectric-La2CuO4, monocrystals
Abstract Measurements of transmission and photoconductivity spectra in submillimeter wave length range as well as of capacity C and conductivity G in the region of acoustic frequencies of metal-dielectric-La2CuO4 system at low temperatures are performed using La2CuO4 monocrystals. Optical spectra posses a threshold character, a sharp decrease of transmission and photocoductivity signal occurs in the energy region hν>1.5 MeV. C(ω,T) and G(ω, T) dependences have a universal form typical of Debye type relaxation processes. Relaxation time dependence is of thermoactivated character τ(T)∼exp(ξ/T) with the gap value ξ≅2 meV. It is assumed that excitations with characteristic energy of ∼2 meV exist in La2CuO4. A possible nature of the detected low-energy excitations is discussed.
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Call Number Serial 1688
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Author Elezov, M. S.; Scherbatenko, M. L.; Sych, D. V.; Goltsman, G. N.
Title Active and passive phase stabilization for the all-fiber Michelson interferometer Type Conference Article
Year 2018 Publication J. Phys.: Conf. Ser. Abbreviated Journal J. Phys.: Conf. Ser.
Volume 1124 Issue Pages 051014 (1 to 5)
Keywords (up) Michelson interferometer, phase stabilization
Abstract We put forward two methods for phase stabilization in the all-fiber Michelson interferometer. To perform passive phase stabilization, we use a heat bath for all fibers and electro-optical components, and put the interferometer in a hermetic case. To perform active phase stabilization, we monitor output power of the interferometer and develop an electronic feedback control. The phase stabilization methods enable stable interference pattern for several minutes, and can be helpful for the development of the optimal quantum receiver for coherent signals.
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ISSN 1742-6588 ISBN Medium
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Notes Approved no
Call Number Serial 1299
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Author Finkel, M.; Thierschmann, H. R.; Galatro, L.; Katan, A. J.; Thoen, D. J.; de Visser, P. J.; Spirito, M.; Klapwijk, T. M.
Title Branchline and directional THz coupler based on PECVD SiNx-technology Type Conference Article
Year 2016 Publication 41st IRMMW-THz Abbreviated Journal 41st IRMMW-THz
Volume Issue Pages
Keywords (up) microstrip, fixtures, coplanar waveguides, couplers, standards, probes, dielectrics
Abstract A fabrication technology to realize THz microstrip lines and passive circuit components is developed and tested making use of a plasma-enhanced chemical vapor deposition grown silicon nitride (PECVD SiNx) dielectric membrane. We use 2 μm thick SiNx and 300 nm thick gold layers on sapphire substrates. We fabricate a set of structures for thru-reflect-line (TRL) calibration, with the reflection standard implemented as a short through the via. We find losses of 9.5 dB/mm at 300 GHz for a 50 Ohm line. For a branchline coupler we measure 2.5 dB insertion loss, 1 dB amplitude imbalance and 21 dB isolation. Good control over the THz lines parameters is proven by similar performance of a set of 5 structures. The directional couplers show -14 dB transmission to the coupled port, -24 dB to the isolated port and -25 dB in reflection. The SiNx membrane, used as a dielectric, is compatible with atomic force microscopy (AFM) cantilevers allowing the application of this technology to the development of a THz near-field microscope.
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ISSN 2162-2035 ISBN 978-1-4673-8485-8 Medium
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Notes Approved no
Call Number 7758586 Serial 1295
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Author Shcherbatenko, Michael; Lobanov, Yury; Finkel, Matvey; Maslennikov, Sergey; Pentin, Ivan; Semenov, Alexander; Titova, Nadezhda; Kaurova, Natalya; Voronov, Boris M.; Rodin, Alexander; Klapwijk, Teunis M.; Gol’tsman, Gregory N.
Title Development of a 30 THz heterodyne receiver based on a hot-electron-bolometer mixer Type Abstract
Year 2014 Publication Proc. 25th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 25th Int. Symp. Space Terahertz Technol.
Volume Issue Pages 122
Keywords (up) mid-IR NbN HEB mixers, GaAs substrates
Abstract We present new Hot-Electron-Bolometer (HEB) mixers designed for mid-IR spectroscopy targeting astrophysical and geophysical observations where high sensitivity and spectral resolution are required. The mixers are made of an ultrathin NbN film deposited on GaAs substrates. Two entirely different types of the devices have been fabricated. The first type is based on a direct radiation coupling concept and the mixing devices are shaped as squares of 5×5 μm 2 (which corresponds to the diffraction limit at the chosen wavelength) and 10×10 μm 2 (which was used to establish a possible influence of the contact pads on the radiation absorption). The second type utilizes a spiral antenna designed with HFSS. The fabrication and layout of the devices as well as the performance comparison will be presented. During the experiments, the HEB mixer was installed on the cold plate of a LHe cryostat. A germanium window and an extended semi-spherical germanium lens are used to couple the radiation. The cryostat is equipped with a germanium optical filter of thickness 0.5 mm and with a center wavelength of 10.6 mμ. The incident power absorption is measured by using the isothermal method. As a Local Oscillator, a 10.6 micrometers line of a CO2 gas laser is used. We further characterize the frequency response of the spiral antenna with a FIR-spectrometer. The noise characteristics of the mixers are determined from a room temperature cold load and a heated black body at ~600 K as a hot load.
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Call Number Serial 1364
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Author Семенов, А. В.; Корнеев, А. А.; Лобанов, Ю. В.; Корнеева, Ю. П.; Рябчун, С. А.; Третьяков, И. В.; Флоря, И. Н.; Смирнов, А. В.; Ковалюк, В. В.; Смирнов, К. В.; Гольцман, Г. Н.
Title Оценка поляризационных искажений, вносимых оптической системой радиотелескопа миллиметрового диапазона Type Journal Article
Year 2012 Publication Преподаватель ХХI век Abbreviated Journal
Volume Issue 4 Pages 230-236
Keywords (up) millimeter radio telescope
Abstract В статье рассмотрена поляризация электромагнитного поля вблизи фокальной точки телескопической системы. Оценена верхняя граница поляризационных искажений, вносимых отражающими поверхностями, в том числе с учетом неидеальности отражения.
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Language Russian Summary Language Original Title
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Notes Approved no
Call Number Serial 1821
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