| Records |
| Author |
Hübers, H.-W.; Semenov, A.; Holldack, K.; Schade, U.; Wüstefeld, G.; Gol’tsman, G. |
Title  |
Time domain analysis of coherent terahertz synchrotron radiation |
Type |
Journal Article |
| Year |
2005 |
Publication |
Appl. Phys. Lett. |
Abbreviated Journal |
Appl. Phys. Lett. |
| Volume |
87 |
Issue |
18 |
Pages |
184103 (1 to 3) |
| Keywords |
NbN HEB mixers, applications |
| Abstract |
The time structure of coherent terahertz synchrotron radiation at the electron storage ring of the Berliner Elektronensynchrotron und Speicherring Gesellschaft has been analyzed with a fast superconducting hot-electron bolometer. The emission from a single bunch of electrons was found to last ∼1500ps at frequencies around 0.4THz, which is much longer than the length of an electron bunch in the time domain (∼5ps). It is suggested that this is caused by multiple reflections at the walls of the beam line. The quadratic increase of the power with the number of electrons in the bunch as predicted for coherent synchrotron radiation and the transition from stable to bursting radiation were determined from a single storage ring fill pattern of bunches with different populations. |
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| ISSN |
0003-6951 |
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1457 |
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| Author |
Zhang, J.; Słysz, W.; Pearlman, A.; Verevkin, A.; Sobolewski, R.; Okunev, O.; Chulkova, G.; Gol’tsman, G. N. |
| Title |
Time delay of resistive-state formation in superconducting stripes excited by single optical photons |
Type |
Journal Article |
| Year |
2003 |
Publication |
Phys. Rev. B |
Abbreviated Journal |
Phys. Rev. B |
| Volume |
67 |
Issue |
13 |
Pages |
132508 (1 to 4) |
| Keywords |
NbN SSPD, SNSPD |
| Abstract |
We have observed a 65(±5)-ps time delay in the onset of a resistive-state formation in 10-nm-thick, 130-nm-wide NbN superconducting stripes exposed to single photons. The delay in the photoresponse decreased to zero when the stripe was irradiated by multi-photon (classical) optical pulses. Our NbN structures were kept at 4.2 K, well below the material’s critical temperature, and were illuminated by 100-fs-wide optical pulses. The time-delay phenomenon has been explained within the framework of a model based on photon-induced generation of a hotspot in the superconducting stripe and subsequent, supercurrent-assisted, resistive-state formation across the entire stripe cross section. The measured time delays in both the single-photon and two-photon detection regimes agree well with theoretical predictions of the resistive-state dynamics in one-dimensional superconducting stripes. |
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| ISSN |
0163-1829 |
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no |
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1519 |
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Shurakov, A.; Mikhalev, P.; Mikhailov, D.; Mityashkin, V.; Tretyakov, I.; Kardakova, A.; Belikov, I.; Kaurova, N.; Voronov, B.; Vasil’evskii, I.; Gol’tsman, G. |
| Title |
Ti/Au/n-GaAs planar Schottky diode with a moderately Si-doped matching sublayer |
Type |
Journal Article |
| Year |
2018 |
Publication |
Microelectronic Engineering |
Abbreviated Journal |
Microelectronic Engineering |
| Volume |
195 |
Issue |
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Pages |
26-31 |
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| Abstract |
In this paper, we report on the results of the study of the Ti/Au/n-GaAs planar Schottky diodes (PSD) intended for the wideband detection of terahertz radiation. The two types of the PSD devices were compared having either the dual n/n+ silicon dopant profile or the triple one with a moderately doped matching sublayer inserted. All the diodes demonstrated no noticeable temperature dependence of ideality factors and barrier heights, whose values covered the ranges of 1.15–1.50 and 0.75–0.85 eV, respectively. We observed the lowering of the flat band barrier height of ∼80 meV after introducing the matching sublayer into the GaAs sandwich. For both the devices types, the series resistance value as low as 20 Ω was obtained. To extract the total parasitic capacitance, we performed the Y-parameters analysis within the electromagnetic modeling of the PSD's behavior via the finite-element method. The capacitance values of 12–12.2 fF were obtained and further verified by measuring the diodes' response voltages in the frequency range of 400–480 GHz. We also calculated the AC current density distribution within the layered structures similar to those being experimentally studied. It was demonstrated that insertion of the moderately Si-doped matching sublayer might be beneficial for implementation of a PSD intended for the operation within the ‘super-THz’ frequency range. |
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0167-9317 |
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1155 |
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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. |
| 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 |
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. |
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Institute of Photonics, University of Eastern Finland, Yliopistokatu 7, FI-80101 Joensuu, Finland |
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English |
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2073-4360 |
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PMID:33353036; PMCID:PMC7767186 |
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1780 |
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Palma, F.; Teppe, F.; Fatimy, A. E.; Green, R.; Xu, J.; Vachontin, Y.; Tredicucci, A.; Goltsman, G.; Knap, W. |
| Title |
THz communication system based on a THz quantum cascade laser and a hot electron bolometer |
Type |
Conference Article |
| Year |
2010 |
Publication |
35th Int. Conf. Infrared, Millimeter, and Terahertz Waves |
Abbreviated Journal |
35th Int. Conf. Infrared, Millimeter, and Terahertz Waves |
| Volume |
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Issue |
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Pages |
11623798 (1 to 2) |
| Keywords |
QCL, HEB detector |
| Abstract |
We present the experimental study of the direct emission – detection system based on the THz Quantum Cascade Laser as a source and Hot Electron Bolometer (HEB) detector – in view of its application as an optical communication system. We show that the system can efficiently transmit the QCL Terahertz pulses. We estimate the maximal modulation speed of the system to be about several GHz and show that it is limited only by the QCL pulse power supply, detector amplifier and connection line/wires parameters. |
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1391 |
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