| Records |
| Author |
Casaburi, A.; Ejrnaes, M.; Quaranta, O.; Gaggero, A.; Mattioli, F.; Leoni, R.; Voronov, B.; Gol'tsman, G.; Lisitskiy, M.; Esposito, E.; Nappi, C.; Cristiano, R.; Pagano, S. |
| Title |
Experimental characterization of NbN nanowire optical detectors with parallel stripline configuration |
Type |
Conference Article |
| Year |
2008 |
Publication |
J. Phys.: Conf. Ser. |
Abbreviated Journal  |
J. Phys.: Conf. Ser. |
| Volume |
97 |
Issue |
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Pages |
012265 (1 to 6) |
| Keywords |
NbN SSPD, SNSPD |
| Abstract |
We have developed a novel geometrical configuration for NbN-based superconducting single photon optical detector (SSPD) that achieves two goals: a much lower intrinsic impedance, and a consequently greater bandwidth, and a much larger signal amplitude compared to the standard meandered configuration. This has been obtained by implementing a properly designed parallel stripline structure where a cascade switching mechanism occurs when one of the striplines is hit by an optical photon. The overall switching occurs synchronously and in a very short time, giving rise to a strong and fast voltage pulse. The SSPD have been realized using state of the art NbN deposition technology and e-beam lithography. The strips are 100 nm wide and 5 μm long and have been realized with 4 nm NbN film on sapphire and Si substrate. We report on experimental characterization of such novel devices. The performances of the proposed novel type of SSPD are compared with standard SSPD design and results in terms of signal amplitude, risetime and effective detection area. |
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| Publisher |
IOP Publishing |
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| ISSN |
1742-6596 |
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Conference |
8th European Conference on Applied Superconductivity (EUCAS 2007) |
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no |
| Call Number |
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Serial |
1416 |
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| Author |
Milostnaya, I.; Korneev, A.; Rubtsova, I.; Seleznev, V.; Minaeva, O.; Chulkova, G.; Okunev, O.; Voronov, B.; Smirnov, K.; Gol'tsman, G.; Slysz, W.; Wegrzecki, M.; Guziewicz, M.; Bar, J.; Gorska, M.; Pearlman, A.; Kitaygorsky, J.; Cross, A.; Sobolewski, R. |
| Title |
Superconducting single-photon detectors designed for operation at 1.55-µm telecommunication wavelength |
Type |
Conference Article |
| Year |
2006 |
Publication |
J. Phys.: Conf. Ser. |
Abbreviated Journal |
J. Phys.: Conf. Ser. |
| Volume |
43 |
Issue |
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Pages |
1334-1337 |
| Keywords |
NbN SSPD, SNSPD |
| Abstract |
We report on our progress in development of superconducting single-photon detectors (SSPDs), specifically designed for secure high-speed quantum communications. The SSPDs consist of NbN-based meander nanostructures and operate at liquid helium temperatures. In general, our devices are capable of GHz-rate photon counting in a spectral range from visible light to mid-infrared. The device jitter is 18 ps and dark counts can reach negligibly small levels. The quantum efficiency (QE) of our best SSPDs for visible-light photons approaches a saturation level of ~30-40%, which is limited by the NbN film absorption. For the infrared range (1.55µm), QE is ~6% at 4.2 K, but it can be significantly improved by reduction of the operation temperature to the 2-K level, when QE reaches ~20% for 1.55-µm photons. In order to further enhance the SSPD efficiency at the wavelength of 1.55 µm, we have integrated our detectors with optical cavities, aiming to increase the effective interaction of the photon with the superconducting meander and, therefore, increase the QE. A successful effort was made to fabricate an advanced SSPD structure with an optical microcavity optimized for absorption of 1.55 µm photons. The design consisted of a quarter-wave dielectric layer, combined with a metallic mirror. Early tests performed on relatively low-QE devices integrated with microcavities, showed that the QE value at the resonator maximum (1.55-µm wavelength) was of the factor 3-to-4 higher than that for a nonresonant SSPD. Independently, we have successfully coupled our SSPDs to single-mode optical fibers. The completed receivers, inserted into a liquid-helium transport dewar, reached ~1% system QE for 1.55 µm photons. The SSPD receivers that are fiber-coupled and, simultaneously, integrated with resonators are expected to be the ultimate photon counters for optical quantum communications. |
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Edition |
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| ISSN |
1742-6588 |
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Approved |
no |
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Serial |
1450 |
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| Author |
Zorin, M.; Lindgren, M.; Danerud, M.; Karasik, B.; Winkler, D.; Gol'tsman, G.; Gershenzon, E. |
| Title |
Nonequilibrium and bolometric responses of YBaCuO thin films to high-frequency modulated laser radiation |
Type |
Journal Article |
| Year |
1995 |
Publication |
J. Supercond. |
Abbreviated Journal |
J. Supercond. |
| Volume |
8 |
Issue |
1 |
Pages |
11-15 |
| Keywords |
YBCO HTS HEB |
| Abstract |
Picosecond nonequilibrium and slow bolometric responses to infrared radiation from a patterned high-T c superconducting (HTS) film in resistive and normal states deposited onto LaAlO3, NdGaO3, and MgO substrates were investigated using both pulse and modulation techniques. The response time of 35 ps to a laser pulse of 17 ps FWHM has been observed. The intrinsic response time of the fast process is expected to be about a few picoseconds. The modulation technique, being free from the disadvantages of pulse methods (poor sensitivity, limited dynamic range), makes the detailed study of a number of relaxation processes possible. Besides the nonequilibrium response, two kinds of bolometric processes, namely phonon transport through the film-substrate interface and phonon thermal diffusion in a substrate, manifest themselves in certain frequency dependences. |
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Series Issue |
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Edition |
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| ISSN |
0896-1107 |
ISBN |
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| Notes |
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Approved |
no |
| Call Number |
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Serial |
1630 |
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| Author |
Gol'tsman, G. N.; Goghidze, I. G.; Kouminov, P. B.; Karasik, B. S.; Semenov, A. D.; Gershenzon, E. M. |
| Title |
Influence of grain boundary weak links on the nonequilibrium response of YBaCuO thin films to short laser pulses |
Type |
Journal Article |
| Year |
1994 |
Publication |
J. Supercond. |
Abbreviated Journal |
J. Supercond. |
| Volume |
7 |
Issue |
4 |
Pages |
751-755 |
| Keywords |
YBCO HTS detector, nonequilibrium response |
| Abstract |
The transient voltage response in both epitaxial and granular YBaCuO thin films to 80 ps pulses of YAG∶Nd laser radiation of wavelength 0.63 and 1.54 μm was studied. In the normal and resistive states both types of films demonstrate two components: a nonequilibrium picosecond component and a bolometric nanosecond one. The normalized amplitudes are almost the same for all films. In the superconducting state we observed a kinetic inductive response and two-component shape after integration. The normalized amplitude of the response in granular films is up to five orders of magnitude larger than in epitaxial films. We interpret the nonequilibrium response in terms of a suppression of the order parameter by the excess of quasiparticles followed by the change of resistance in the normal and resistive states or kinetic inductance in the superconducting state. The sharp rise of inductive response in granular films is explained both by a diminishing of the cross section for current percolation through the disordered network of Josephson weak links and by a decrease of condensate density in neighboring regions. |
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Edition |
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| ISSN |
0896-1107 |
ISBN |
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no |
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Serial |
1636 |
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| Author |
Sergeev, A.; Semenov, A.; Trifonov, V.; Karasik, B.; Gol'tsman, G.; Gershenzon, E. |
| Title |
Heat transfer in YBaCuO thin film/sapphire substrate system |
Type |
Journal Article |
| Year |
1994 |
Publication |
J. Supercond. |
Abbreviated Journal |
J. Supercond. |
| Volume |
7 |
Issue |
2 |
Pages |
341-344 |
| Keywords |
YBCO films |
| Abstract |
The thermal boundary resistance at the YBaCuO thin film/Al2O3 substrate interface was investigated. The transparency for thermal phonons incident on the interface as well as for phonons moving from the substrate was determined. We have measured a transient voltage response of current-biased films to continuously modulated radiation. The observed knee in the modulation frequency dependence of the response reflects the crossover from the diffusion regime to the contact resistance regime of the heat transfer across the interface. The values of transparency were independently deduced both from the phonon escape time and from the time of phonon return to the film which were identified with peculiarities in the frequency dependence. The results are much more consistent with the acoustic mismatch theory than the diffuse mismatch model. |
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Edition |
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| ISSN |
0896-1107 |
ISBN |
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Serial |
1647 |
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