| Records |
| Author |
Lobanov, Y. V.; Vakhtomin, Y. B.; Pentin, I. V.; Rosental, V. A.; Smirnov, K. V.; Goltsman, G. N.; Volkov, O. Y.; Dyuzhikov, I. N.; Galiev, R. R.; Ponomarev, D. S.; Khabibullin, R. A. |
| Title |
Time-resolved measurements of light–current characteristic and mode competition in pulsed THz quantum cascade laser |
Type |
Journal Article |
| Year |
2021 |
Publication |
Optical Engineering |
Abbreviated Journal |
Optical Engineering |
| Volume |
60 |
Issue |
8 |
Pages  |
1-8 |
| Keywords |
HEB, terahertz pulse generation, terahertz pulse detection, QCL, quantum cascade laser, superconducting hot electron bolometer |
| Abstract |
Quantum cascade lasers (QCL) are widely adopted as prominent and easy-to-use solid-state sources of terahertz radiation. Yet some applications require generation and detection of very sharp and narrow terahertz-range pulses with a specific spectral composition. We have studied time-resolved light-current (L–I) characteristics of multimode THz QCL operated with a fast ramp of the injection current. Detection of THz pulses was carried out using an NbN superconducting hot-electron bolometer with the time constant of the order of 1 ns while the laser bias current was swept during a single driving pulse. A nonmonotonic behavior of the L–I characteristic with several visually separated subpeaks was found. This behavior is associated with the mode competition in THz QCL cavity, which we confirm by L–I measurements with use of an external Fabry–Perot interferometer for a discrete mode selection. We also have demonstrated the possibility to control the L–I shape with suppression of one of the subpeaks by simply adjusting the off-axis parabolic mirror for optimal optical alignment for one of the laser modes. The developed technique paves the way for rapid characterization of pulsed THz QCLs for further studies of the possibilities of using this approach in remote sensing. |
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10.1117/1.Oe.60.8.082019 |
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1260 |
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Saveskul, N. A.; Titova, N. A.; Baeva, E. M.; Semenov, A. V.; Lubenchenko, A. V.; Saha, S.; Reddy, H.; Bogdanov, S. I.; Marinero, E. E.; Shalaev, V. M.; Boltasseva, A.; Khrapai, V. S.; Kardakova, A. I.; Goltsman, G. N. |
| Title |
Superconductivity behavior in epitaxial TiN films points at surface magnetic disorder |
Type |
Miscellaneous |
| Year |
2019 |
Publication |
arXiv |
Abbreviated Journal |
arXiv |
| Volume |
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1-10 |
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We analyze the evolution of the normal and superconducting electronic properties in epitaxial TiN films, characterized by high Ioffe-Regel parameter values, as a function of the film thickness. As the film thickness decreases, we observe an increase of in the residual resistivity, which becomes dominated by diffusive surface scattering for d≤20nm. At the same time, a substantial thickness-dependent reduction of the superconducting critical temperature is observed compared to the bulk TiN value. In such a high quality material films, this effect can be explained by a weak magnetic disorder residing in the surface layer with a characteristic magnetic defect density of ∼1012cm−2. Our results suggest that surface magnetic disorder is generally present in oxidized TiN films. |
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1278 |
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Kardakova, A. I.; Coumou, P. C. J. J.; Finkel, M. I.; Morozov, D. V.; An, P. P.; Goltsman, G. N.; Klapwijk, T. M. |
| Title |
Electron–phonon energy relaxation time in thin strongly disordered titanium nitride films |
Type |
Journal Article |
| Year |
2015 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
| Volume |
25 |
Issue |
3 |
Pages |
1-4 |
| Keywords |
TiN MKID |
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We have measured the energy relaxation times from the electron bath to the phonon bath in strongly disordered TiN films grown by atomic layer deposition. The measured values of τ eph vary from 12 to 91 ns. Over a temperature range from 3.4 to 1.7 K, they follow T -3 temperature dependence, which are consistent with values of τ eph reported previously for sputtered TiN films. For the most disordered film, with an effective elastic mean free path of 0.35 nm, we find a faster relaxation and a stronger temperature dependence, which may be an additional indication of the influence of strong disorder on a superconductor. |
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1051-8223 |
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1296 |
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Korneev, A.; Korneeva, Y.; Florya, I.; Semenov, A.; Goltsman, G. |
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Photon switching statistics in multistrip superconducting single-photon detectors |
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Journal Article |
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2018 |
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IEEE Trans. Appl. Supercond. |
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IEEE Trans. Appl. Supercond. |
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28 |
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7 |
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1-4 |
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SSPD, SNSPD |
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We study photon count statistics in superconducting single-photon detectors consisting of up to 70 narrow superconducting strips connected in parallel. Using interarrival time analysis, we demonstrate that our samples are operated in the “arm-trigger” regime and require up to seven subsequently absorbed photons to form a resistive state in the whole sample. We also performed numerical simulation of the light and dark count rates versus detector bias current, which are in good agreement with the experimental results. |
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1051-8223 |
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1304 |
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Goltsman, G. |
| Title |
Superconducting thin film as infrared heterodyne and direct detectors |
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Conference Article |
| Year |
2017 |
Publication |
16th ISEC |
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16th ISEC |
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1-3 |
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optical waveguide SSPD, SNSPD |
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We present our recent achievements in the development of superconducting nanowire single-photon detectors (SNSPDs) integrated with optical waveguides on a chip. We demonstrate both single-photon counting with up to 90% on-chip-quantum-efficiency (OCDE), and the heterodyne mixing with a close to the quantum limit sensitivity at the telecommunication wavelength using single device. |
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8314188 |
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1323 |
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