Hajenius, M., Baselmans, J. J. A., Gao, J. R., Klapwijk, T. M., de Korte 2, P. A. J., Voronov, B., et al. (2004). Increased bandwidth of NbN phonon cooled hot electron bolometer mixers. In Proc. 15th Int. Symp. Space Terahertz Technol. (pp. 381–386).
Abstract: We study experimentally the IF gain bandwidth of NbN phonon-cooled hot-electron-bolometer (HEB) mixers for a set of devices with different contact structures but an identical NbN film. We observe that the IF bandwidth depends strongly on the exact contact structure and find an IF gain bandwidth of 6 GHz for a device with an additional superconducting layer (NbTiN) in between the active NbN film and the gold contact to the antenna. These results contradict the common opinion that the IF bandwidth is determined by the phonon-escape time between the NbN film and the substrate. Hence we calculate the IF gain bandwidth of a superconducting film using a two-temperature model. We find that the bandwidth increases strongly with operating temperature and is not limited by the phonon escape time. This is because of strong temperature dependence of the phonon specific heat in the NbN film.
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Tong, C. E., Blundell, R., Papa, D. C., Smith, M., Kawamura, J., Gol'tsman, G., et al. (1999). An all solid-state superconducting heterodyne receiver at terahertz frequencies. IEEE Microw. Guid. Wave Lett., 9(9), 366–368.
Abstract: A superconducting hot-electron bolometer mixer-receiver operating from 1 to 1.26 THz has been developed. This heterodyne receiver employs two solid-state local oscillators each consisting of a Gunn oscillator followed by two stages of varactor frequency multiplication. The measured receiver noise temperature is 1350 K at 1.035 THz and 2700 K at 1.26 THz. This receiver demonstrates that tunable solid-state local oscillators, supplying only a few micro-watts of output power, can be used in terahertz receiver applications.
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Cherednichenko, S., Khosropanah, P., Adam, A., Merkel, H. F., Kollberg, E. L., Loudkov, D., et al. (2003). 1.4- to 1.7-THz NbN hot-electron bolometer mixer for the Herschel space observatory. In T. G. Phillips, & J. Zmuidzinas (Eds.), Proc. SPIE (Vol. 4855, pp. 361–370). SPIE.
Abstract: NbN hot- electron bolometer mixers have reached the level of 10hv/k in terms of the input noise temperature with the noise bandwidth of 4-6 GHz from subMM band up to 2.5 THz. In this paper we discuss the major characteristics of this kind of receiver, i.e. the gain and the noise bandwidth, the noise temperature in a wide RF band, bias regimes and optimisation of RF coupling to the quasioptical mixer. We present the status of the development of the mixer for Band 6 Low for Herschel Telescope.
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Yngvesson, K. S., Gerecht, E., Musante, C. F., Zhuang, Y., Ji, M., Goyette, T. M., et al. (1999). Low-noise HEB heterodyne receivers and focal plane arrays for the THz regime using NbN. In R. J. Hwu, & K. Wu (Eds.), Proc. SPIE (Vol. 3795, pp. 357–368). SPIE.
Abstract: We have developed prototype HEB receivers using thin film superconducting NbN devices deposited on silicon substrates. The devices are quasi-optically coupled through a silicon lens and a self-complementary log-specific toothed antenna. We measured DSB receiver noise temperatures of 500 K (13 X hf/2k) at 1.56 THz and 1,100 K (20 X hf/2k) at 2.24 THz. Noise temperatures are expected to fall further as devices and quasi-optical coupling methods are being optimized. The measured 3 dB IF conversion gain bandwidth for one device was 3 GHz, and it is estimated that the bandwidth over which the receiver noise temperature is within 3 dB of its minimum value is 6.5 GHz which is sufficient for a number of practical applications. We will discuss our latest results and give a detailed description of our prototype setup and experiments. We will also discuss our plans for developing focal plane arrays with tens of Hot Electron Bolometric mixer elements on a single silicon substrate which will make real time imaging systems in the THz region feasible.
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Hoogeveen, R. W. M., Yagoubov, P. A., Maurellis, A., Koshelets, V. P., Shitov, S. V., Mair, U., et al. (2003). New cryogenic heterodyne techniques applied in TELIS: the balloonborne THz and submillimeter limb sounder for atmospheric research. In M. Strojnik (Ed.), Proc. SPIE (Vol. 5152, pp. 347–355). SPIE.
Abstract: We present a design concept for a new state-of-the-art balloon borne atmospheric monitor that will allow enhanced limb sounding of the Earth’s atmosphere within the submillimeter and far-infrared wavelength spectral range: TELIS, TErahertz and submm LImb Sounder. The instrument is being developed by a consortium of major European institutes that includes the Space Research Organization of the Netherlands (SRON), the Rutherford Appleton Laboratory (RAL) will utilize state-of-the-art superconducting heterodyne technology and is designed to be a compact, lightweight instrument cpaable of providing broad spectral coverage, high spectral resolution and long flight duration ( 24 hours duration during a single flight campaign). The combination of high sensitivity and extensive flight duration will allow evaluation of the diurnal variation of key atmospheric constitutenets sucyh as OH, HO2, ClO, BrO togehter will onger lived constituents such as O3, HCL and N2O. Furthermore, TELIS will share a common balloon platform to that of the MIPAS-B Fourier Transform Spectrometer, developed by the Institute of Meteorology and Climate research of the over an extended spectral range. The combination of the TELIS and MIPAS instruments will provide atmospheric scientists with a very powerful observational tool. TELIS will serve as a testbed for new cryogenic heterodyne detection techniques, and as such it will act as a prelude to future spaceborne instruments planned by the European Space Agency (ESA).
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Vachtomin, Y. B., Antipov, S. V., Kaurova, N. S., Maslennikov, S. N., Smirnov, K. V., Polyakov, S. L., et al. (2004). Noise temperature, gain bandwidth and local oscillator power of NbN phonon-cooled HEB mixer at terahertz frequenciess. In Proc. 29th IRMMW / 12th THz (pp. 329–330). Karlsruhe, Germany.
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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Słysz, W., Wegrzecki, M., Bar, J., Grabiec, P., Górska, M., Zwiller, V., et al. (2007). Fibre-coupled, single photon detector based on NbN superconducting nanostructures for quantum communications. J. Modern Opt., 54(2-3), 315–326.
Abstract: We present a novel, two-channel, single photon receiver based on two fibre-coupled, NbN, superconducting, single photon detectors (SSPDs). The SSPDs are nanostructured superconducting meanders and are known for ultrafast and efficient detection of visible-to-infrared photons. Coupling between the NbN detector and optical fibre was achieved using a micromechanical photoresist ring placed directly over the SSPD, holding the fibre in place. With this arrangement, we obtained coupling efficiencies up to ∼30%. Our experimental results showed that the best receiver had a near-infrared system quantum efficiency of 0.33% at 4.2 K. The quantum efficiency increased exponentially with the photon energy increase, reaching a few percent level for visible-light photons. The photoresponse pulses of our devices were limited by the meander high kinetic inductance and had the rise and fall times of approximately 250 ps and 5 ns, respectively. The receiver's timing jitter was in the 37 to 58 ps range, approximately 2 to 3 times larger than in our older free-space-coupled SSPDs. We stipulate that this timing jitter is in part due to optical fibre properties. Besides quantum communications, the two-detector arrangement should also find applications in quantum correlation experiments.
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Yagoubov, P., Gol'tsman, G., Voronov, B., Svechnikov, S., Cherednichenko, S., Gershenzon, E., et al. (1996). Quasioptical phonon-cooled NbN hot-electron bolometer mixer at THz frequencies. In Proc. 7th Int. Symp. Space Terahertz Technol. (pp. 303–317).
Abstract: In our experiments we tested phonon-cooled hot-electron bolometer (HEB) quasioptical mixer based on spiral antenna designed for 0.5-1.2 THz frequency band and fabricated on sapphire, Si-coated sapphire and high resistivity silicon substrates. HEB devices were produced from thin superconducting NbN film 3.5-6 nm thick with the critical temperature of about 11-12 K. For these devices we achieved the receiver noise temperature T R (DSB) = 3000 K in the 500-700 GHz frequency range and an IF bandwidth of 3-4 GHz. Prelimanary measurements at frequencies 1-1.2 THz resulted the receiver noise temperature about 9000 K (DSB).
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Kaurova, N. S., Finkel, M. I., Maslennikov, S. N., Vahtomin, Y. B., Antipov, S. V., Smirnov, K. V., et al. (2004). Submillimeter mixer based on YBa2Cu3O7-x thin film. In Proc. 1-st conf. Fundamental problems of high temperature superconductivity (291). Moscow-Zvenigorod.
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Yagubov, P., Gol'tsman, G., Voronov, B., Seidman, L., Siomash, V., Cherednichenko, S., et al. (1996). The bandwidth of HEB mixers employing ultrathin NbN films on sapphire substrate. In Proc. 7th Int. Symp. Space Terahertz Technol. (pp. 290–302). Charlottesville, Virginia, USA.
Abstract: We report on some unusual features observed during fabrication of ultrathin NbN films with high Tc. The films were used to fabricate HEB mixers, which were evaluated for IF bandwidth measurements at 140 GHz. Ultrathin films were fabricated using reactive dc magnetron sputtering with a discharge current source. Reproducible parameters of the films are assured keeping constant the difference between the discharge voltage in pure argon, and in a gas mixture, for the same current. A maximum bandwidth of 4 GHz at optimal LO and dc bias was obtained for mixer chip based on NbN film 35 A thick with Tc = 11 K.
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