Records |
Author |
Chulkova, G.; Milostnaya, I.; Korneev, A.; Minaeva, O.; Rubtsova, I.; Voronov, B.; Okunev, O.; Smirnov, K.; Gol’tsman, G.; Kitaygorsky, J.; Cross, A.; Pearlman, A.; Sobolewski, R.; Slysz, W. |
Title |
Superconducting nanostructures for counting of single photons in the infrared range |
Type |
Conference Article |
Year |
2005 |
Publication |
Proc. 2-nd CAOL |
Abbreviated Journal |
Proc. 2-nd CAOL |
Volume |
2 |
Issue |
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Pages |
100-103 |
Keywords |
SSPD, SNSPD |
Abstract ![sorted by Abstract field, ascending order (up)](img/sort_asc.gif) |
We present our studies on ultrafast superconducting single-photon detectors (SSPDs) based on ultrathin NbN nanostructures. Our SSPDs are patterned by electron beam lithography from 4-nm thick NbN film into meander-shaped strips covering square area of 10/spl times/10 /spl mu/m/sup 2/. The advances in the fabrication technology allowed us to produce highly uniform 100-120-nm-wide strips with meander filling factor close to 0.6. The detectors exploit a combined detection mechanism, where upon a single-photon absorption, an avalanche of excited hot electrons and the biasing supercurrent, jointly produce a picosecond voltage transient response across the superconducting nanostrip. The SSPDs are typically operated at 4.2 K, but they have shown that their sensitivity in the infrared radiation range can be significantly improved by lowering the operating temperature from 4.2 K to 2 K. When operated at 2 K, the SSPD quantum efficiency (QE) for visible light photons reaches 30-40%, which is the saturation value limited by optical absorption of our 4-nm-thick NbN film. For 1.55 /spl mu/m photons, QE was /spl sim/20% and decreases exponentially with the increase of the optical wavelength, but even at the wavelength of 6 /spl mu/m the detector remains sensitive to single photons and exhibits QE of about 10/sup -2/%. The dark (false) count rate at 2 K is as low as 2 /spl times/ 10/sup -4/ s/sup -1/, what makes our detector essentially a background-limited sensor. The very low dark-count rate results in the noise equivalent power (NEP) as low as 10/sup -18/ WHz/sup -1/2/ for the mid-infrared range (6 /spl mu/m). Further improvement of the SSPD performance in the mid-infrared range can be obtained by substituting NbN for the other, lower-T/sub c/ superconductors with the narrow superconducting gap and low quasiparticle diffusivity. The use of such materials will shift the cutoff wavelength towards the values even longer than 6 /spl mu/m. |
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Second International Conference on Advanced Optoelectronics and Lasers |
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Serial |
1461 |
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Author |
Kitaygorsky, J.; Zhang, J.; Verevkin, A.; Sergeev, A.; Korneev, A.; Matvienko, V.; Kouminov, P.; Smirnov, K.; Voronov, B.; Gol'tsman, G.; Sobolewski, R. |
Title |
Origin of dark counts in nanostructured NbN single-photon detectors |
Type |
Journal Article |
Year |
2005 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
Volume |
15 |
Issue |
2 |
Pages |
545-548 |
Keywords |
SSPD dark counts, SNSPD, dark counts rate |
Abstract ![sorted by Abstract field, ascending order (up)](img/sort_asc.gif) |
We present our study of dark counts in ultrathin (3.5 to 10 nm thick), narrow (120 to 170 nm wide) NbN superconducting stripes of different lengths. In experiments, where the stripe was completely isolated from the outside world and kept at temperature below the critical temperature Tc, we detected subnanosecond electrical pulses associated with the spontaneous appearance of the temporal resistive state. The resistive state manifested itself as generation of phase-slip centers (PSCs) in our two-dimensional superconducting stripes. Our analysis shows that not far from Tc, PSCs have a thermally activated nature. At lowest temperatures, far below Tc, they are created by quantum fluctuations. |
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1057 |
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Author |
Semenov, A.; Richter, H.; Hübers, H.-W.; Smirnov, K.; Voronov, B.; Gol'tsman, G. |
Title |
Development of terahertz superconducting hot-electron bolometer mixers |
Type |
Conference Article |
Year |
2003 |
Publication |
Proc. 6th European Conf. Appl. Supercond. |
Abbreviated Journal |
Proc. 6th European Conf. Appl. Supercond. |
Volume |
181 |
Issue |
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Pages |
2960-2965 |
Keywords |
NbN HEB mixers |
Abstract ![sorted by Abstract field, ascending order (up)](img/sort_asc.gif) |
We present recent results of the development of phonon cooled hot-electron bolometric (HEB) mixers for airborne and balloon borne terahertz heterodyne receivers. Three iomportant issues have been addresses: the quality of NbN films the HEB mixers were made from, the spectral properties of the HEB mixers and the local oscillator power required for optical operation. Studies with an atomic force microscope indicate, that the performance of the HEB mixer might have been effected by the microstructure of the NbN film. Antenna gain and noise temperature were investigated at terahertz frequencies for a HEB embedded in either log-spiral or twin-slot feed antenna. Comparison suggests that at frequencies above 3 THz the spiral feed provides better overall performance. At 1.6 THz, a power of 2.5 µW was required from the local oscillator for optimal operation of the HEB mixer. |
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Sorrento, Italy |
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0750309814, 978-0750309813 |
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1505 |
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Semenov, A. D.; Hübers, Heinz-Wilhelm; Richter, H.; Birk, M.; Krocka, M.; Mair, U.; Vachtomin, Yu. B.; Finkel, M. I.; Antipov, S. V.; Voronov, B. M.; Smirnov, K. V.; Kaurova, N. S.; Drakinski, V. N.; Gol'tsman, G. N. |
Title |
Superconducting hot-electron bolometer mixer for terahertz heterodyne receivers |
Type |
Journal Article |
Year |
2003 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
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Volume |
13 |
Issue |
2 |
Pages |
168-171 |
Keywords |
NbN HEB mixers |
Abstract ![sorted by Abstract field, ascending order (up)](img/sort_asc.gif) |
We present recent results showing the development of superconducting NbN hot-electron bolometer mixer for German receiver for astronomy at terahertz frequencies and terahertz limb sounder. The mixer is incorporated into a planar feed antenna, which has either logarithmic spiral or double-slot configuration, and backed on a silicon lens. The hybrid antenna had almost frequency independent and symmetric radiation pattern slightly broader than expected for a diffraction limited antenna. At 2.5 THz the best 2200 K double side-band receiver noise temperature was achieved across a 1 GHz intermediate frequency bandwidth centred at 1.5 GHz. For this operation regime, a receiver conversion efficiency of -17 dB was directly measured and the loss budget was evaluated. The mixer response was linear at load temperatures smaller than 400 K. Implementation of the MgO buffer layer on Si resulted in an increased 5.2 GHz gain bandwidth. The receiver was tested in the laboratory environment by measuring a methanol emission line at 2.5 THz. |
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343 |
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Chulkova, G.; Milostnaya, I.; Tarkhov, M.; Korneev, A.; Minaeva, O.; Voronov, B.; Divochiy, A.; Gol'tsman, G.; Kitaygorsky, J.; Pan, D.; Sobolewski, R. |
Title |
Superconducting single-photon nanostructured detectors for advanced optical applications |
Type |
Conference Article |
Year |
2006 |
Publication |
Proc. Symposium on Photonics Technologies for 7th Framework Program |
Abbreviated Journal |
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Volume |
400 |
Issue |
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Pages |
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Keywords |
SSPD, SNSPD |
Abstract ![sorted by Abstract field, ascending order (up)](img/sort_asc.gif) |
We present superconducting single-photon detectors (SSPDs) based on NbN thin-film nanostructures and operated at liquid helium temperatures. The SSPDs are made of ultrathin NbN films (2.5-4 nm thick, Tc= 9-11K) as meander-shaped nanowires covering the area of 10× 10 µm2. Our detectors are operated at the temperature well below the critical temperature Tc and are DC biased by a current Ib close to the meander critical current Ic. The operation principle of the detector is based on the use of the resistive region in a narrow ultra-thin superconducting stripe upon the absorption of an incident photon. The developed devices demonstrate high sensitivity and response speed in a broadband range from UV to mid-IR (up to 6 µm), making them very attractive for advanced optical technologies, which require efficient detectors of single quanta and low-density optical radiation. |
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RPLAB @ sasha @ chulkova2006superconducting |
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1021 |
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