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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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Finkel, M. I., Maslennikov, S. N., & Gol'tsman, G. N. (2005). Terahertz heterodyne receivers based on superconductive hot-electron bolometer mixers. Radiophys. Quant. Electron., 48(10-11), 859–864.
Abstract: We consider recent results in development of hot-electron bolometer mixers. Special attention is paid to optimization of the contacts between the antenna and the active area of a superconducting film. An important result in the study of the parasitic effect of direct detection is obtained during the measurement of the noise temperatures by the hot/cold load method. The latest results of studies of the waveguide hot-electron bolometer mixers and their successful practical applications are considered. Progress in development of high-frequency (over 1.3 THz) heterodyne receivers for several important international projects is discussed and new submillimeter radio astronomy projects ESPRIT and SAFIR are described.
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Finkel, M. I., Maslennikov, S. N., & Gol'tsman, G. N. (2007). The concept of the receiving complex for the “Millimetron” space radio telescope. Radiophys. Quant. Electron., 50(10-11), 837–846.
Abstract: We consider the current status of research in the development of a submillimeter and far-infrared receiving instrument and propose promising solutions for the receivers of the spaceborne telescope “Millimetron,” which allow one to realize comprehensively the opportunities given by this international project administrated by the Astrospace Center of the P. N. Lebedev Physical Institute of the Russian Academy of Sciences.
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Svechnikov, S. I., Finkel, M. I., Maslennikov, S. N., Vachtomin, Y. B., Smirnov, K. V., Seleznev, V. A., et al. (2006). Superconducting hot electron bolometer mixer for middle IR range. In Proc. 16th Int. Crimean Microwave and Telecommunication Technology (Vol. 2, pp. 686–687).
Abstract: The developed directly lens coupled hot electron bolometer (HEB) mixer was based on 5 nm superconducting NbN deposited on GaAs substrate. The layout of the structure, including 30x20 mcm^2 active area coupled with a 50 Ohm coplanar line, was patterned by photolithography. The responsivity of the mixer was measured in a direct detection mode in the 25-64 THz frequency range. The noise performance of the mixer and the directivity of the receiver were investigated in a heterodyne mode. A 10.6 mum wavelength CW CO2 laser was utilized as a local oscillator.
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Vachtomin, Y. B., Antipov, S. V., Maslennikov, S. N., Smirnov, K. V., Polyakov, S. L., Zhang, W., et al. (2006). Quasioptical hot electron bolometer mixers based on thin NBN films for terahertz region. In Proc. 16th Int. Crimean Microwave and Telecommunication Technology (Vol. 2, pp. 688–689).
Abstract: Presented in this paper are the performances of HEB mixers based on 2-3.5 nm thick NbN films integrated with log-periodic spiral antenna. Double side-band receiver noise temperature values are 1300 K and 3100 K at 2.5 THz and at 3.8 THz, respectively. Mixer gain bandwidth is 5.2 GHz. Local oscillator power is 1-3 muW for mixers with different active area
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