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Author |
Il'in, K. S.; Verevkin, A. A.; Gol'tsman, G. N.; Sobolewski, R. |
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Title |
Infrared hot-electron NbN superconducting photodetectors for imaging applications |
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Journal Article |
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Year |
1999 |
Publication |
Supercond. Sci. Technol. |
Abbreviated Journal |
Supercond. Sci. Technol. |
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Volume  |
12 |
Issue |
11 |
Pages |
755-758 |
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Keywords |
NbN SSPD, SNSPD |
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Abstract |
We report an effective quantum efficiency of 340, responsivity >200 A W-1 (>104 V W-1) and response time of 27±5 ps at temperatures close to the superconducting transition for NbN superconducting hot-electron photodetectors (HEPs) in the near-infrared and optical ranges. Our studies were performed on a few nm thick NbN films deposited on sapphire substrates and patterned into µm-size multibridge detector structures, incorporated into a coplanar transmission line. The time-resolved photoresponse was studied by means of subpicosecond electro-optic sampling with 100 fs wide laser pulses. The quantum efficiency and responsivity studies of our photodetectors were conducted using an amplitude-modulated infrared beam, fibre-optically coupled to the device. The observed picosecond response time and the very high efficiency and sensitivity of the NbN HEPs make them an excellent choice for infrared imaging photodetectors and input optical-to-electrical transducers for superconducting digital circuits. |
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0953-2048 |
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1562 |
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Author |
Rönnung, F.; Cherednichenko, S.; Winkler, D.; Gol'tsman, G. N. |
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Title |
A nanoscale YBCO mixer optically coupled with a bow tie antenna |
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Journal Article |
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Year |
1999 |
Publication |
Supercond. Sci. Technol. |
Abbreviated Journal |
Supercond. Sci. Technol. |
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12 |
Issue |
11 |
Pages |
853-855 |
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Keywords |
YBCO HTS HEB mixers |
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Abstract |
The bolometric response of YBa2Cu3O7-δ(YBCO) hot-electron bolometers (HEBs) to near-infrared radiation was studied. Devices were fabricated from a 50 nm thick film and had in-plane areas of 10 × 10 µm2, 2 × 0.2 µm2, 1 × 0.2µm2 and 0.5 × 0.2 µm2. We found that nonequilibrium phonons cool down more effectively for the bolometers with smaller area. For the smallest bolometer the bolometric component in the response is 10 dB less than for the largest one. |
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0953-2048 |
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1563 |
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Gorokhov, G.; Bychanok, D.; Gayduchenko, I.; Rogov, Y.; Zhukova, E.; Zhukov, S.; Kadyrov, L.; Fedorov, G.; Ivanov, E.; Kotsilkova, R.; Macutkevic, J.; Kuzhir, P. |
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Title |
THz spectroscopy as a versatile tool for filler distribution diagnostics in polymer nanocomposites |
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Journal Article |
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2020 |
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Polymers (Basel) |
Abbreviated Journal |
Polymers (Basel) |
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12 |
Issue |
12 |
Pages |
3037 (1 to 14) |
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Keywords |
THz spectroscopy; nanocomposites, percolation threshold, time-domain spectroscopy, time-domain spectrometer, TDS |
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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. |
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Institute of Photonics, University of Eastern Finland, Yliopistokatu 7, FI-80101 Joensuu, Finland |
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2073-4360 |
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PMID:33353036; PMCID:PMC7767186 |
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1780 |
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Gol’tsman, G.; Okunev, O.; Chulkova, G.; Lipatov, A.; Dzardanov, A.; Smirnov, K.; Semenov, A.; Voronov, B.; Williams, C.; Sobolewski, R. |
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Title |
Fabrication and properties of an ultrafast NbN hot-electron single-photon detector |
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Journal Article |
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Year |
2001 |
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IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
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Volume |
11 |
Issue |
1 |
Pages |
574-577 |
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Keywords |
NbN SSPD, SNSPD |
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A new type of ultra-high-speed single-photon counter for visible and near-infrared wavebands based on an ultrathin NbN hot-electron photodetector (HEP) has been developed. The detector consists of a very narrow superconducting stripe, biased close to its critical current. An incoming photon absorbed by the stripe produces a resistive hotspot and causes an increase in the film’s supercurrent density above the critical value, leading to temporary formation of a resistive barrier across the device and an easily measurable voltage pulse. Our NbN HEP is an ultrafast (estimated response time is 30 ps; registered time, due to apparatus limitations, is 150 ps), frequency unselective device with very large intrinsic gain and negligible dark counts. We have observed sequences of output pulses, interpreted as single-photon events for very weak laser beams with wavelengths ranging from 0.5 /spl mu/m to 2.1 /spl mu/m and the signal-to-noise ratio of about 30 dB. |
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1558-2515 |
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1547 |
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Nikoghosyan, A. S.; Martirosyan, R. M.; Hakhoumian, A. A.; Makaryan, A. H.; Tadevosyan, V. R.; Goltsman, G. N.; Antipov, S. V. |
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Title |
Effect of absorption on the efficiency of THz radiation generation in a nonlinear crystal placed into a waveguide |
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Journal Article |
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Year |
2018 |
Publication |
Armenian J. Phys. |
Abbreviated Journal |
Armenian J. Phys. |
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Volume |
11 |
Issue |
4 |
Pages |
257-262 |
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Keywords |
THz, waveguide, nonlinear crystal |
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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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1829-1171 |
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1291 |
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