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Pentin, I., Finkel, M., Maslennikov, S., Vakhtomin, Y., Smirnov, K., Kaurova, N., et al. (2017). Superconducting hot-electron-bolometer mixers for the mid-IR. Rus. J. Radio Electron., (10), http://jre.cplire.ru/jre/oct17/9/text.pdf. Retrieved July 3, 2024, from http://jre.cplire.ru/jre/oct17/9/abstract_e.html
Abstract: The work presents the result of development of the NbN superconducting hot-electron-bolometer (HEB) mixer. The sensitive element of the mixer is directly coupled to mid-IR radiation, and doesn’t have planar metallic antenna. Investigations of noise characteristics of NbN HEB mixer were performed at the frequency 28.4 THz (λ = 10.6 µm) by using gas-discharge CW CO2-laser without consideration of optical and electrical losses in the heterodyne receiver. The noise temperature of NbN HEB mixer with the size of the sensitive element 10 µm × 10 µm was 2320 K (~ 1.5hν/kB) at the heterodyne frequency of 28.4 THz. The noise temperature was determined by measuring the Y-factor taking into account the term which describes fluctuations of zero-point oscillations in accordance with the fluctuation-dissipation theorem of Calle-Welton. Isothermal method was used to estimate the absorbed heterodyne radiation power which was 9 µW at the optimal operating point for the minimum noise temperature of NbN HEB mixer.
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Karasik, B. S., Il'in, K. S., Pechen, E. V., & Krasnosvobodtsev, S. I. (1996). Diffusion cooling mechanism in a hot-electron NbC microbolometer mixer. Appl. Phys. Lett., 68(16), 2285–2287.
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Karasik, B. S., & Elantiev, A. I. (1996). Noise temperature limit of a superconducting hot-electron bolometer mixer. Appl. Phys. Lett., 68(6), 853–855.
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Tretyakov, I. V., Finkel, M. I., Ryabchun, S. A., Kardakova, A. I., Seliverstov, S. V., Petrenko, D. V., et al. (2014). Hot-electron bolometer mixers with in situ contacts. Radiophys. Quant. Electron., 56(8-9), 591–598.
Abstract: We report on the latest achievements in the development of superconducting hot-electron bolometer (HEB) mixers for terahertz superheterodyne receivers. We consider application ranges of such receivers and requirements for the basic characteristics of the mixers. Main features of the mixers, such as noise temperature, gain bandwidth, noise bandwidth, and required local-oscillator power, have been improved significantly over the past few years due to intense research work, both in terms of the element fabrication quality and in terms of understanding of the physics of the processes occurring in the HEB mixers. Contacts between the superconducting bridge and the planar antenna play a key role in the mixer operation. Improvement of the quality of the contacts leads simultaneously to a decrease in the noise temperature and an increase in the gain bandwidth of a mixer.
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Seliverstov, S. V., Anfertyev, V. A., Tretyakov, I. V., Ozheredov, I. A., Solyankin, P. M., Revin, L. S., et al. (2017). Terahertz heterodyne receiver with an electron-heating mixer and a heterodyne based on the quantum-cascade laser. Radiophys. Quant. Electron., 60(7), 518–524.
Abstract: We study characteristics of the laboratory prototype of a terahertz heterodyne receiver with an electron-heating mixer and a heterodyne based on the quantum-cascade laser. The results obtained demonstrate the possibility to use this receiver as a basis for creation of a high-sensitivity terahertz spectrometer, which can be used in many basic and practical applications. A significant advantage of this receiver will be the possibility of placing the mixer and heterodyne in the same cryostat, which will reduce the device dimensions considerably. The obtained experimental results are analyzed, and methods of optimizing the parameters of the receiver are proposed.
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Tretyakov, I. V., Anfertyev, V. A., Revin, L. S., Kaurova, N. S., Voronov, B. M., Vaks, V. L., et al. (2018). Sensitivity and resolution of a heterodyne receiver based on the NbN HEB mixer with a quantum-cascade laser as a local oscillator. Radiophys. Quant. Electron., 60(12), 988–992.
Abstract: We present the results of experimental studies of the basic characteristics and operation features of a terahertz heterodyne detector based on the superconducting NbN HEB mixer and a quantum cascade laser as a local oscillator operating at a frequency of 2.02 THz. The measured noise temperature of such a mixer amounted to 1500 K. The spectral resolution of the detector is determined by the width of the local-oscillator spectral line whose measured value does not exceed 1 MHz. The quantum-cascade laser could be linearly tuned with respect to frequency with the coefficient 7.2 MHz/mA within the limits of the current oscillation bandwidth.
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Pentin, I. V., Smirnov, A. V., Ryabchun, S. A., Ozhegov, R. V., Gol’tsman, G. N., Vaks, V. L., et al. (2012). Semiconducting superlattice as a solid-state terahertz local oscillator for NbN hot-electron bolometer mixers. Tech. Phys., 57(7), 971–974.
Abstract: We present the results of our studies of the semiconducting superlattice (SSL) frequency multiplier and its application as part of the solid state local oscillator (LO) in the terahertz heterodyne receiver based on a NbN hot-electron bolometer (HEB) mixer. We show that the SSL output power level increases as the ambient temperature is lowered to 4.2 K, the standard HEB operation temperature.
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Ozhegov, R. V., Gorshkov, K. N., Okunev, O. V., & Gol’tsman, G. N. (2010). Superconducting hot-electron bolometer mixer as element of thermal imager matrix. Tech. Phys. Lett., 36(11), 1006–1008.
Abstract: The possibility of using a matrix of sensitive elements on a 12-mm-diameter hyperhemispherical lens in a thermal imager operating in the terahertz range has been studied. Dimensions of a lens region acceptable for arrangement of the matrix, in which the receiver noise temperature varies within 16% of the mean value, are determined to be 3.3% of the lens diameter. Deviations of the main lobe of the directivity pattern are evaluated, which amount to ±1.25° relative to the direction toward the optimum position of a mixer. The fluctuation sensitivity of the receiver measured in experiment is 0.5 K at a frequency of 300 GHz.
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Tret’yakov, I. V., Ryabchun, S. A., Kaurova, N. S., Larionov, P. A., Lobastova, A. A., Voronov, B. M., et al. (2010). Optimum absorbed heterodyne power for superconducting NbN hot-electron bolometer mixer. Tech. Phys. Lett., 36(12), 1103–1105.
Abstract: Absorbed heterodyne power has been measured in a low-noise broadband hot-electron bolometer (HEB) mixer for the terahertz range, operating on the effect of electron heating in the resistive state of an ultrathin superconducting NbN film. It is established that the optimum absorbed heterodyne power for the HEB mixer operating at 2.5 THz is about 100 nW.
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Gol'tsman, G., Maslennikov, S., Finkel, M., Antipov, S., Kaurova, N., Grishina, E., et al. (2006). Nanostructured ultrathin NbN film as a terahertz hot-electron bolometer mixer. In Proc. MRS (Vol. 935, 210 (1 to 6)).
Abstract: Planar spiral antenna coupled and directly lens coupled NbN HEB mixer structures are studied. An additional MgO buffer layer between the superconducting film and Si substrate is introduced. The buffer layer enables us to increase the gain bandwidth of a HEB mixer due to better acoustic transparency. The gain bandwidth is widened as NbN film thickness decreases and amounts to 5.2 GHz. The noise temperature of antenna coupled mixer is 1300 and 3100 K at 2.5 and 3.8 THz respectively. The structure and composition of NbN films is investigated by X-ray diffraction spectroscopy methods. Noise performance degradation at LO frequencies more than 3 THz is due to the use of a planar antenna and signal loss in contacts between the antenna and the sensitive NbN bridge. The mixer is reconfigured for operation at higher frequencies in a manner that receiver’s noise temperature is only 2300 K (3 times of quantum limit) at LO frequency of 30 THz.
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