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Meledin, D., Tong, C. Y. - E., Blundell, R., Kaurova, N., Smirnov, K., Voronov, B., et al. (2003). Study of the IF bandwidth of NbN HEB mixers based on crystalline quartz substrate with an MgO buffer layer. IEEE Trans. Appl. Supercond., 13(2), 164–167.
Abstract: In this paper, we present the results of IF bandwidth measurements on 3-4 nm thick NbN hot electron bolometer waveguide mixers, which have been fabricated on a 200-nm thick MgO buffer layer deposited on a crystalline quartz substrate. The 3-dB IF bandwidth, measured at an LO frequency of 0.81 THz, is 3.7 GHz at the optimal bias point for low noise receiver operation. We have also made measurements of the IF dynamic impedance, which allow us to evaluate the intrinsic electron temperature relaxation time and self-heating parameters at different bias conditions.
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Meledin, D., Tong, C. - Y. E., Blundell, R., & Goltsman, G. (2003). Measurement of intermediate frequency bandwidth of hot electron bolometer mixers at terahertz frequency range. IEEE Microw. Wireless Compon. Lett., 13(11), 493–495.
Abstract: We have developed a new experimental setup for measuring the IF bandwidth of superconducting hot electron bolometer mixers. In our measurement system we use a chopped hot filament as a broadband signal source, and can perform a high-speed IF scan with no loss of accuracy when compared to coherent methods. Using this technique we have measured the 3 dB IF bandwidth of hot electron bolometer mixers, designed for THz frequency operation, and made from 3-4 nm thick NbN film deposited on an MgO buffer layer over crystalline quartz.
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Meledin, D., Pavolotsky, A., Desmaris, V., Lapkin, I., Risacher, C., Perez, V., et al. (2009). A 1.3-THz balanced waveguide HEB mixer for the APEX telescope. IEEE Trans. Microw. Theory Techn., 57(1), 89–98.
Abstract: In this paper, we report about the development, fabrication, and characterization of a balanced waveguide hot electron bolometer (HEB) receiver for the Atacama Pathfinder EXperiment telescope covering the frequency band of 1.25–1.39 THz. The receiver uses a quadrature balanced scheme and two HEB mixers, fabricated from 4- to 5-nm-thick NbN film deposited on crystalline quartz substrate with an MgO buffer layer in between. We employed a novel micromachining method to produce all-metal waveguide parts at submicrometer accuracy (the main-mode waveguide dimensions are 90×180 μm). We present details on the mixer design and measurement results, including receiver noise performance, stability and “first-light†at the telescope site. The receiver yields a double-sideband noise temperature averaged over the RF band below 1200 K, and outstanding stability with a spectroscopic Allan time more than 200 s.
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Mel’nikov, A. P., Gurvich, Y. A., Shestakov, L. N., & Gershenzon, E. M. (2001). Magnetic field effects on the nonohmic impurity conduction of uncompensated crystalline silicon. Jetp Lett., 73(1), 44–47.
Abstract: The impurity conduction of a series of crystalline silicon samples with the concentration of major impurity N ≈ 3 × 1016 cm−3 and with a varied, but very small, compensation K was measured as a function of the electric field E in various magnetic fields H-σ(H, E). It was found that, at K < 10−3 and in moderate E, where these samples are characterized by a negative nonohmicity (dσ(0, E)/dE < 0), the ratio σ(H, E)/σ(0, E) > 1 (negative magnetoresistance). With increasing E, these inequalities are simultaneously reversed (positive nonohmicity and positive magnetoresistance). It is suggested that both negative and positive nonohmicities are due to electron transitions in electric fields from impurity ground states to states in the Mott-Hubbard gap.
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Men’shchikov, E. M., Gogidze, I. G., Sergeev, A. V., Elant’ev, A. I., Kuminov, P. B., Gol’tsman, G. N., et al. (1997). Superconducting fast detector based on the nonequilibrium inductance response of a film of niobium nitride. Tech. Phys. Lett., 23(6), 486–488.
Abstract: A new type of fast detector is proposed, whose operation is based on the variation of the kinetic inductance of a superconducting film caused by nonequilibrium quasiparticles created by the electromagnetic radiation. The speed of the detector is determined by the rate of multiplication of photo-excited quasiparticles, and is nearly independent of the temperature, being less than 1 ps for NbN. Models based on the Owen-Scalapino scheme give a good description of the experimentally determined dependence of the power-voltage sensitivity of the detector on the modulation frequency. The lifetime of the quasiparticles is determined, and it is shown that the reabsorption of nonequilibrium phonons by the condensate has a substantial effect even in ultrathin NbN films 5 nm thick, and results in the maximum possible quantum yield. A low concentration of equilibrium quasiparticles and a high quantum yield result in a detectivity D*=1012 W−1·Hz1/2 at a temperature T=4.2 K and D*=1016 W−1·cm· Hz1/2 at T=1.6 K.
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Milostnaya, I., Korneev, A., Tarkhov, M., Divochiy, A., Minaeva, O., Seleznev, V., et al. (2008). Superconducting single photon nanowire detectors development for IR and THz applications. J. Low Temp. Phys., 151(1-2), 591–596.
Abstract: We present our progress in the development of superconducting single-photon detectors (SSPDs) based on meander-shaped nanowires made from few-nm-thick superconducting films. The SSPDs are operated at a temperature of 2–4.2 K (well below T c ) being biased with a current very close to the nanowire critical current at the operation temperature. To date, the material of choice for SSPDs is niobium nitride (NbN). Developed NbN SSPDs are capable of single photon counting in the range from VIS to mid-IR (up to 6 μm) with a record low dark counts rate and record-high counting rate. The use of a material with a low transition temperature should shift the detectors sensitivity towards longer wavelengths. We present state-of-the art NbN SSPDs as well as the results of our recent approach to expand the developed SSPD technology by the use of superconducting materials with lower T c , such as molybdenum rhenium (MoRe). MoRe SSPDs first were made and tested; a single photon response was obtained.
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Mohan, N., Minaeva, O., Gol'tsman, G. N., Nasr, M. B., Saleh, B. E., Sergienko, A. V., et al. (2008). Photon-counting optical coherence-domain reflectometry using superconducting single-photon detectors. Opt. Express, 16(22), 18118–18130.
Abstract: We consider the use of single-photon counting detectors in coherence-domain imaging. Detectors operated in this mode exhibit reduced noise, which leads to increased sensitivity for weak light sources and weakly reflecting samples. In particular, we experimentally demonstrate the possibility of using superconducting single-photon detectors (SSPDs) for optical coherence-domain reflectometry (OCDR). These detectors are sensitive over the full spectral range that is useful for carrying out such imaging in biological samples. With counting rates as high as 100 MHz, SSPDs also offer a high rate of data acquisition if the light flux is sufficient.
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Mohan, N., Minaeva, O., Goltsman, G. N., Saleh, M. F., Nasr, M. B., Sergienko, A. V., et al. (2009). Ultrabroadband coherence-domain imaging using parametric downconversion and superconducting single-photon detectors at 1064 nm. Appl. Opt., 48(20), 4009–4017.
Abstract: Coherence-domain imaging systems can be operated in a single-photon-counting mode, offering low detector noise; this in turn leads to increased sensitivity for weak light sources and weakly reflecting samples. We have demonstrated that excellent axial resolution can be obtained in a photon-counting coherence-domain imaging (CDI) system that uses light generated via spontaneous parametric downconversion (SPDC) in a chirped periodically poled stoichiometric lithium tantalate (chirped-PPSLT) structure, in conjunction with a niobium nitride superconducting single-photon detector (SSPD). The bandwidth of the light generated via SPDC, as well as the bandwidth over which the SSPD is sensitive, can extend over a wavelength region that stretches from 700 to 1500 nm. This ultrabroad wavelength band offers a near-ideal combination of deep penetration and ultrahigh axial resolution for the imaging of biological tissue. The generation of SPDC light of adjustable bandwidth in the vicinity of 1064 nm, via the use of chirped-PPSLT structures, had not been previously achieved. To demonstrate the usefulness of this technique, we construct images for a hierarchy of samples of increasing complexity: a mirror, a nitrocellulose membrane, and a biological sample comprising onion-skin cells.
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Morozov, D. V., Smirnov, K. V., Smirnov, A. V., Lyakhov, V. A., & Goltsman, G. N. (2005). A millimeter-submillimeter phonon-cooled hot-electron bolometer mixer based on two-dimensional electron gas in an AlGaAs/GaAs heterostructure. Semicond., 39(9), 1082–1086.
Abstract: Experimental results obtained by studying the main characteristics of a millimeter-submillimeter wave mixer based on the hot-electron effect in a two-dimensional electron gas in a AlGaAs/GaAs heterostructure with a phonon-scattering cooling mechanism for charge carriers are reported. The gain bandwidth of the mixer is 4 GHz, the internal conversion losses are 13 dB, and the optimum local-oscillator power is 0.5 μW (for a mixer area of 1 μm2). It is shown that a millimeter-submillimeter-wave receiver with a noise temperature of 1900 K can be developed on the basis of a AlGaAs/GaAs mixer. This mixer also appears to be promising for use in array receiver elements.
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Morozov, P., Lukina, M., Shirmanova, M., Divochiy, A., Dudenkova, V., Gol'tsman, G. N., et al. (2021). Singlet oxygen phosphorescence imaging by superconducting single-photon detector and time-correlated single-photon counting. Opt. Lett., 46(6), 1217–1220.
Abstract: This Letter presents, to the best of our knowledge, a novel optical configuration for direct time-resolved measurements of luminescence from singlet oxygen, both in solutions and from cultured cells on photodynamic therapy. The system is based on the superconducting single-photon detector, coupled to the confocal scanner that is modified for the near-infrared measurements. The recording of a phosphorescence signal from singlet oxygen at 1270 nm has been done using time-correlated single-photon counting. The performance of the system is verified by measuring phosphorescence from singlet oxygen generated by the photosensitizers commonly used in photodynamic therapy: methylene blue and chlorin e6. The described system can be easily upgraded to the configuration when both phosphorescence from singlet oxygen and fluorescence from the cells can be detected in the imaging mode. Thus, co-localization of the signal from singlet oxygen with the areas inside the cells can be done.
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