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Author Rasulova, G. K.; Pentin, I. V.; Vakhtomin, Y. B.; Smirnov, K. V.; Khabibullin, R. A.; Klimov, E. A.; Klochkov, A. N.; Goltsman, G. N. url  doi
openurl 
  Title Pulsed terahertz radiation from a double-barrier resonant tunneling diode biased into self-oscillation regime Type Journal Article
  Year 2020 Publication J. Appl. Phys. Abbreviated Journal J. Appl. Phys.  
  Volume 128 Issue 22 Pages 224303 (1 to 11)  
  Keywords HEB, resonant tunneling diode, RTD  
  Abstract The study of the bolometer response to terahertz (THz) radiation from a double-barrier resonant tunneling diode (RTD) biased into the negative differential conductivity region of the I–V characteristic revealed that the RTD emits two pulses in a period of intrinsic self-oscillations of current. The bolometer pulse repetition rate is a multiple of the fundamental frequency of the intrinsic self-oscillations of current. The bolometer pulses are detected at two critical points with a distance between them being half or one-third of a period of the current self-oscillations. An analysis of the current self-oscillations and the bolometer response has shown that the THz photon emission is excited when the tunneling electrons are trapped in (the first pulse) and then released from (the second pulse) miniband states.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0021-8979 ISBN Medium  
  Area Expedition Conference  
  Notes (up) Approved no  
  Call Number Serial 1262  
Permanent link to this record
 
 
Author Sidorova, M.; Semenov, Alexej D.; Hübers, H.-W.; Ilin, K.; Siegel, M.; Charaev, I.; Moshkova, M.; Kaurova, N.; Goltsman, G. N.; Zhang, X.; Schilling, A. url  doi
openurl 
  Title Electron energy relaxation in disordered superconducting NbN films Type Journal Article
  Year 2020 Publication Phys. Rev. B Abbreviated Journal Phys. Rev. B  
  Volume 102 Issue 5 Pages 054501 (1 to 15)  
  Keywords NbN SSPD, SNSPD, HEB, bandwidth, relaxation time  
  Abstract We report on the inelastic-scattering rate of electrons on phonons and relaxation of electron energy studied by means of magnetoconductance, and photoresponse, respectively, in a series of strongly disordered superconducting NbN films. The studied films with thicknesses in the range from 3 to 33 nm are characterized by different Ioffe-Regel parameters but an almost constant product qTl (qT is the wave vector of thermal phonons and l is the elastic mean free path of electrons). In the temperature range 14–30 K, the electron-phonon scattering rates obey temperature dependencies close to the power law 1/τe−ph∼Tn with the exponents n≈3.2–3.8. We found that in this temperature range τe−ph and n of studied films vary weakly with the thickness and square resistance. At 10 K electron-phonon scattering times are in the range 11.9–17.5 ps. The data extracted from magnetoconductance measurements were used to describe the experimental photoresponse with the two-temperature model. For thick films, the photoresponse is reasonably well described without fitting parameters, however, for thinner films, the fit requires a smaller heat capacity of phonons. We attribute this finding to the reduced density of phonon states in thin films at low temperatures. We also show that the estimated Debye temperature in the studied NbN films is noticeably smaller than in bulk material.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2469-9950 ISBN Medium  
  Area Expedition Conference  
  Notes (up) Approved no  
  Call Number Serial 1266  
Permanent link to this record
 
 
Author Ovchinnikov, O. V.; Perepelitsa, A. S.; Smirnov, M. S.; Latyshev, A. N.; Grevtseva, I. G.; Vasiliev, R. B.; Goltsman, G. N.; Vitukhnovsky, A. G. url  doi
openurl 
  Title Luminescence of colloidal Ag2S/ZnS core/shell quantum dots capped with thioglycolic acid Type Journal Article
  Year 2020 Publication J. Luminescence Abbreviated Journal J. Luminescence  
  Volume 220 Issue Pages 117008 (1 to 7)  
  Keywords Ag2S QD, quantum dots  
  Abstract The features of IR luminescence of colloidal AgS QDs passivated with thioglycolic acid (AgS/TGA) under the formation of AgS/ZnS/TGA core/shell QDs are considered. A 4.5-fold increase in the quantum yield of recombination IR luminescence within the band with a peak at 960 nm (1.29 eV), full width at half maximum of 250 nm (0.34 eV), and the Stokes shift with respect to the exciton absorption of 0.6 eV was found. The increase in the IR luminescence intensity of AgS/ZnS/TGA QDs is accompanied by an increase in the average luminescence lifetime from 2.9 ns to 14.3 ns, which is explained as “healing” of surface trap states during the formation of the ZnS shell. For the first time, the enhancement of the luminescence intensity photodegradation (hereinafter referred to as fatigue) was found during the formation of the AgS/ZnS/TGA core/shell QDs. The luminescence fatigue is irreversible. We conclude that the initial stage of photolysis of the AgS core QDs under laser irradiation plays a key role. Low-atomic photolytic clusters of silver formed on the AgS core QDs act as luminescence quenching centers and do not reveal structural transformations into AgS, provided that the clusters are not in contact with TGA.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0022-2313 ISBN Medium  
  Area Expedition Conference  
  Notes (up) Approved no  
  Call Number Serial 1267  
Permanent link to this record
 
 
Author Shcherbatenko, M. L.; Elezov, M. S.; Goltsman, G. N.; Sych, D. V. url  doi
openurl 
  Title Sub-shot-noise-limited fiber-optic quantum receiver Type Journal Article
  Year 2020 Publication Phys. Rev. A Abbreviated Journal Phys. Rev. A  
  Volume 101 Issue 3 Pages 032306 (1 to 5)  
  Keywords SSPD mixer, SNSPD  
  Abstract We experimentally demonstrate a quantum receiver based on the Kennedy scheme for discrimination between two phase-modulated weak coherent states. The receiver is assembled entirely from standard fiber-optic elements and operates at a conventional telecom wavelength of 1.55 μm. The local oscillator and the signal are transmitted through different optical fibers, and the displaced signal is measured with a high-efficiency superconducting nanowire single-photon detector. We show the discrimination error rate is two times below that of a shot-noise-limited receiver with the same system detection efficiency.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2469-9926 ISBN Medium  
  Area Expedition Conference  
  Notes (up) Approved no  
  Call Number Serial 1268  
Permanent link to this record
 
 
Author Matyushkin, Y.; Kaurova, N.; Voronov, B.; Goltsman, G.; Fedorov, G. url  doi
openurl 
  Title On chip carbon nanotube tunneling spectroscopy Type Journal Article
  Year 2020 Publication Fullerenes, Nanotubes and Carbon Nanostructures Abbreviated Journal  
  Volume 28 Issue 1 Pages 50-53  
  Keywords carbon nanotubes, CNT, scanning tunneling microscope, STM  
  Abstract We report an experimental study of the band structure of individual carbon nanotubes (SCNTs) based on investigation of the tunneling density of states, i.e. tunneling spectroscopy. A common approach to this task is to use a scanning tunneling microscope (STM). However, this approach has a number of drawbacks, to overcome which, we propose another method – tunneling spectroscopy of SCNTs on a chip using a tunneling contact. This method is simpler, cheaper and technologically advanced than the STM. Fabrication of a tunnel contact can be easily integrated into any technological route, therefore, a tunnel contact can be used, for example, as an additional tool in characterizing any devices based on individual CNTs. In this paper we demonstrate a simple technological procedure that results in fabrication of good-quality tunneling contacts to carbon nanotubes.  
  Address  
  Corporate Author Thesis  
  Publisher Taylor & Francis Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes (up) Approved no  
  Call Number doi:10.1080/1536383X.2019.1671365 Serial 1269  
Permanent link to this record
 
 
Author Rasulova, G. K.; Pentin, I. V.; Goltsman, G. N. url  doi
openurl 
  Title Terahertz emission from a weakly-coupled GaAs/AlGaAs superlattice biased into three different modes of current self-oscillations Type Journal Article
  Year 2019 Publication AIP Advances Abbreviated Journal AIP Advances  
  Volume 9 Issue 10 Pages 105220  
  Keywords GaAs/AlGaAs superlattice, SL, NbN HEB  
  Abstract Radio-frequency modulated terahertz (THz) emission power from weakly-coupled GaAs/AlGaAs superlattice (SL) has been increased by parallel connection of several SL mesas. Each SL mesa is a self-oscillator with its own oscillation frequency and mode. In coupled non-identical SL mesas biased at different voltages within the hysteresis loop the chaotic, quasiperiodic and frequency-locked modes of self-oscillations of current arise. THz emission was detected when three connected in parallel SL mesas were biased into the frequency-locked and quasiperiodic modes of self-oscillations of current, while in the chaotic mode of those it falls to the noise level.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2158-3226 ISBN Medium  
  Area Expedition Conference  
  Notes (up) Approved no  
  Call Number Serial 1274  
Permanent link to this record
 
 
Author Antipov, S.; Trifonov, A.; Krause, S.; Meledin, D.; Kaurova, N.; Rudzinski, M.; Desmaris, V.; Belitsky, V.; Goltsman, G. url  doi
openurl 
  Title Improved bandwidth of a 2 THz hot-electron bolometer heterodyne mixer fabricated on sapphire with a GaN buffer layer Type Journal Article
  Year 2019 Publication Supercond. Sci. Technol. Abbreviated Journal Supercond. Sci. Technol.  
  Volume 32 Issue 7 Pages 075003  
  Keywords NbN HEB mixer, GaN buffer layer, sapphire substrate  
  Abstract We report on the signal-to-noise and gain bandwidth of a niobium nitride (NbN) hot-electron bolometer (HEB) mixer at 2 THz fabricated on a sapphire substrate with a GaN buffer layer. Two mixers with different DC properties and geometrical dimensions were studied and they demonstrated very close bandwidth performance. The signal-to-noise bandwidth is increased to 8 GHz in comparison to the previous results, obtained without a buffer-layer. The data were taken in a quasi-optical system with the use of the signal-to-noise method, which is close to the signal levels used in actual astrophysical observations. We find an increase of the gain bandwidth to 5 GHz. The results indicate that prior results obtained on a substrate of crystalline GaN can also be obtained on a conventional sapphire substrate with a few micron MOCVD-deposited GaN buffer-layer.  
  Address  
  Corporate Author Thesis  
  Publisher IOP Publishing Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes (up) Approved no  
  Call Number Antipov_2019 Serial 1277  
Permanent link to this record
 
 
Author Nikogosyan, A. S.; Martirosyan, R. M.; Hakhoumian, A. A.; Makaryan, A. H.; Tadevosyan, V. R.; Goltsman, G. N.; Antipov, S. V. url  doi
openurl 
  Title Effect of absorption on the efficiency of terahertz radiation generation in the metal waveguide partially filled with nonlinear crystal LiNbO3, DAST or ZnTe Type Journal Article
  Year 2019 Publication J. Contemp. Phys. Abbreviated Journal J. Contemp. Phys.  
  Volume 54 Issue 1 Pages 97-104  
  Keywords nonlinear crystal, THz, waveguide  
  Abstract The influence of terahertz (THz) radiation absorption on the efficiency of generation of coherent THz radiation in the system ‘nonlinear-optical crystal partially filling the cross section of a rectangular metal waveguide’ has been investigated. The efficiency of the nonlinear frequency conversion of optical laser radiation to the THz range depends on the loss in the system and the fulfillment of the phase-matching (FM) condition in a nonlinear crystal. The method of partially filling of a metal waveguide with a nonlinear optical crystal is used to ensure phase matching. The phase matching is achieved by numerical determination of the thickness of the nonlinear crystal, that is the degree of partial filling of the waveguide. The attenuation of THz radiation caused by losses both in the metal walls of the waveguide and in the crystal was studied, taking into account the dimension of the cross section of the waveguide, the degree of partial filling, and the dielectric constant of the crystal. It is shown that the partial filling of the waveguide with a nonlinear crystal results in an increase in the efficiency of generation of THz radiation by an order of magnitude, owing to the decrease in absorption.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1068-3372 ISBN Medium  
  Area Expedition Conference  
  Notes (up) Approved no  
  Call Number Serial 1289  
Permanent link to this record
 
 
Author Nikoghosyan, A. S.; Martirosyan, R. M.; Hakhoumian, A. A.; Makaryan, A. H.; Tadevosyan, V. R.; Goltsman, G. N.; Antipov, S. V. url  openurl
  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 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.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1829-1171 ISBN Medium  
  Area Expedition Conference  
  Notes (up) Approved no  
  Call Number Serial 1291  
Permanent link to this record
 
 
Author Ren, Y.; Zhang, D. X.; Zhou, K. M.; Miao, W.; Zhang, W.; Shi, S. C.; Seleznev, V.; Pentin, I.; Vakhtomin, Y.; Smirnov, K. url  doi
openurl 
  Title 10.6 μm heterodyne receiver based on a superconducting hot-electron bolometer mixer and a quantum cascade laser Type Journal Article
  Year 2019 Publication AIP Advances Abbreviated Journal AIP Advances  
  Volume 9 Issue 7 Pages 075307  
  Keywords NbN HEB mixers, QCL, IR  
  Abstract We report on the development of a heterodyne receiver at mid-infrared wavelength for high-resolution spectroscopy applications. The receiver employs a superconducting NbN hot electron bolometer as a mixer and a room temperature distributed feedback quantum cascade laser operating at 10.6 μm (28.2 THz) as a local oscillator. The stabilization of the heterodyne receiver has been achieved using a feedback loop controlling the output power of the laser. Improved Allan variance times as well as a double sideband receiver noise temperature of 5000 K and a noise bandwidth of 2.8 GHz of the receiver system are demonstrated.

The work is supported in part by the National Key R&D Program of China under Grant 2018YFA0404701, by the CAS program under Grant QYZDJ-SSW-SLH043 and GJJSTD20180003, by the National Natural Science Foundation of China (NSFC) under Grant 11773083, by the “Hundred Talents Program” of the “Pioneer Initiative”, and in part by the CAS Key Lab for Radio Astronomy.		  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2158-3226 ISBN Medium  
  Area Expedition Conference  
  Notes (up) Approved no  
  Call Number Serial 1293  
Permanent link to this record
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