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Vakhtomin YB, Finkel MI, Antipov SV, Smirnov KV, Kaurova NS, Drakinskii VN, et al. The gain bandwidth of mixers based on the electron heating effect in an ultrathin NbN film on a Si substrate with a buffer MgO layer. J of communications technol & electronics. 2003;48(6):671–5.
Abstract: Measurements of the intermediate frequency band 900 GHz of mixers based on the electron heating effect (EHE) in 2-nm- and 3.5-nm-thick superconducting NbN films sputtered on MgO and Si substrates with buffer MgO layers are presented. A 2-nm-thick superconducting NbN film with a critical temperature of 9.2 K has been obtained for the first time using a buffer MgO layer.
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Semenov A, Richter H, Smirnov K, Voronov B, Gol'tsman G, Hübers H-W. The development of terahertz superconducting hot-electron bolometric mixers. Supercond Sci Technol. 2004;17(5):436–9.
Abstract: We present recent advances in the development of NbN hot-electron bolometric (HEB) mixers for flying terahertz heterodyne receivers. Three important issues have been addressed: the quality of the source NbN films, the effect of the bolometer size on the spectral properties of different planar feed antennas, and the local oscillator (LO) power required for optimal operation of the mixer. Studies of the NbN films with an atomic force microscope indicated a surface structure that may affect the performance of the smallest mixers. Measured spectral gain and noise temperature suggest that at frequencies above 2.5 THz the spiral feed provides better overall performance than the double-slot feed. Direct measurements of the optimal LO power support earlier estimates made in the framework of the uniform mixer model.
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Vachtomin YB, Antipov SV, Maslennikov SN, Smirnov KV, Polyakov SL, Kaurova NS, et al. Noise temperature measurements of NbN phonon-cooled hot electron bolometer mixer at 2.5 and 3.8 THz. In: Proc. 15th Int. Symp. Space Terahertz Technol. Northampton, Massachusetts, USA; 2004. p. 236–41.
Abstract: We present the results of noise temperature measurements of NbN phonon-cooled HEB mixers based on a 3.5 nm NbN film deposited on a high-resistivity Si substrate with a 200 nm – thick MgO buffer layer. The mixer element was integrated with a log-periodic spiral antenna. The noise temperature measurements were performed at 2.5 THz and at 3.8 THz local oscillator frequencies for the 3 µm x 0.2 µm active area devices. The best uncorrected receiver noise temperatures found for these frequencies are 1300 K and 3100 K, respectively. A water vapour discharge laser was used as the LO source. We also present the results of direct detection contribution to the measured Y-factor and of a possible error of noise temperature calculation. This error was more than 8% for the mixer with in-plane dimensions of 2.4 x 0.16 µm 2 at the optimal noise temperature point. The use of a mesh filter enabled us to avoid the effect of direct detection and decrease optical losses by 0.5 dB. The paper is concluded by the investigation results of the mixer polarization response. It was shown that the polarization can differ from the circular one at 3.8 THz by more than 2 dB.
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Ozhegov R, Morozov D, Maslennikov S, Okunev O, Smirnov K, Gol'tsman G. Submillimeter wave range imaging system for registering human body radiation and finding out the things covered under clothes. In: Proc. 3rd Int. exhibition and conf. Non-Destructive Testing Equipment and Devices. Moscow; 2004.
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Ozhegov R, Maslennikov S, Morozov D, Okunev O, Smirnov K, Gol'tsman G. Imaging system for submillimeter wave range. In: Proc. Tenth All-Russian sceintific conference of student-physicists and young sceintists (VNKSF-10). Moscow; 2004.
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Maslennikov S, Vachtomin Y, Antipov S, Smirnov K, Kaurova N, Grishina E, et al. NbN HEB mixers for frequencies of 2.5 and 3.8 THz. In: Proc. Tenth All-Russian sceintific conference of student-physicists and young sceintists (VNKSF-10). Moscow; 2004.
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Antipov SV, Vachtomin YB, Maslennikov SN, Smirnov KV, Kaurova NS, Grishina EV, et al. Noise performance of quasioptical ultrathin NbN hot electron bolometer mixer at 2.5 and 3.8 THz. In: Proc. 5-th MSMW. Vol 2. Kharkov, Ukraine; 2004. p. 592–4.
Abstract: To put space-based and airborne heterodyne instruments into operation at frequencies above 1 THz the superconducting NbN hot-electron bolometer (HEB) will be incorporated into heterodyne receiver as a mixer. At frequencies above 1.3 THz the sensitivity of the NbN HEB mixers outperform the one of the Schottky diodes and SIS-mixers, and the receiver noise temperature of the NbN HEB mixers increase with frequency. In this paper we present the results of the noise temperature measurements within one batch of NbN HEB mixers based on 3.5 mn thick superconducting NbN film grown on Si substrate with MgO buffer layer at the LO frequencies 2.5 THz and 3.8 THz.
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Vachtomin YB, Antipov SV, Kaurova NS, Maslennikov SN, Smirnov KV, Polyakov SL, et al. Noise temperature, gain bandwidth and local oscillator power of NbN phonon-cooled HEB mixer at terahertz frequenciess. In: Proc. 29th IRMMW / 12th THz. Karlsruhe, Germany; 2004. p. 329–30.
Abstract: We present the performances of HEB mixers based on 3.5 nm thick NbN film integrated with log-periodic spiral antenna. The double side-band receiver noise temperature values are 1300 K and 3100 K at 2.5 THz and at 3.8 THz, respectively. The gain bandwidth of the mixer is 4.2 GHz and the noise bandwidth is 5 GHz. The local oscillator power is 1-3 /spl mu/W for mixers with different active area.
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Kaurova NS, Finkel MI, Maslennikov SN, Vahtomin YB, Antipov SV, Smirnov KV, et al. Submillimeter mixer based on YBa2Cu3O7-x thin film. In: Proc. 1-st conf. Fundamental problems of high temperature superconductivity. Moscow-Zvenigorod; 2004. 291.
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Korneev A, Kouminov P, Matvienko V, Chulkova G, Smirnov K, Voronov B, et al. Sensitivity and gigahertz counting performance of NbN superconducting single-photon detectors. Appl Phys Lett. 2004;84(26):5338–40.
Abstract: We have measured the quantum efficiencysQEd, GHz counting rate, jitter, and noise-equivalentpowersNEPdof nanostructured NbN superconducting single-photon detectorssSSPDsdin thevisible to infrared radiation range. Our 3.5-nm-thick and 100- to 200-nm-wide meander-typedevices(total area 10310mm2), operating at 4.2 K, exhibit an experimental QE of up to 20% inthe visible range and,10% at 1.3 to 1.55mm wavelength and are potentially sensitive up tomidinfrareds,10mmdradiation. The SSPD counting rate was measured to be above 2 GHz withjitter,18 ps, independent of the wavelength. The devices’ NEP varies from,10−17W/Hz1/2for1.55mm photons to,10−20W/Hz1/2for visible radiation. Lowering the SSPD operatingtemperature to 2.3 K significantly enhanced its performance, by increasing the QE to,20% andlowering the NEP level to,3310−22W/Hz1/2, both measured at 1.26mm wavelength.
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