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Huebers H-W, Semenov A, Richter H, Birk M, Krocka M, Mair U, et al. Superconducting hot electron bolometer as mixer for far-infrared heterodyne receivers. In: Phillips TG, Zmuidzinas J, editors. Proc. SPIE. Vol 4855. Tucson, USA: SPIE; 2003. p. 395–401. (Presented at the Society of Photo-Optical Instrumentation Engineers (SPIE) Conference; vol 4855).
Abstract: Heterodyne receivers for applications in astronomy need quantum limited sensitivity. In instruments which are currently under development for SOFIA or Herschel superconducting hot electron bolometers (HEB) will be used to achieve this goal at frequencies above 1.4 THz. We present results of the development of a phonon-cooled NbN HEB mixer for GREAT, the German Receiver for Astronomy at Terahertz Frequencies, which will be flown aboard SOFIA. The mixer is a small superconducting bridge incorporated in a planar feed antenna and a hyperhemispherical lens. Mixers with logarithmic-spiral and double-slot feed antennas have been investigated with respect to their noise temperature, conversion loss, linearity and beam pattern. At 2.5 THz a double sideband noise temperature of 2200 K was achieved. The conversion loss was 17 dB. The response of the mixer was linear up to 400 K load temperature. The performance was verified by measuring an emission line of methanol at 2.5 THz. The measured linewidth is in good agreement with the linewidth deduced from pressure broadening measurements at millimeter wavelength. The results demonstrate that the NbN HEB is very well suited as a mixer for far-infrared heterodyne receivers.
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Hübers H-W, Semenov A, Richter H, Birk M, Krocka M, Mair U, et al. Terahertz Heterodyn Receiver with a hot-electron bolometer mixer. In: Wolf U, Farhoomand J, McCreight CR, editors. Far-IR, Sub-mm & MM Detector Technology Workshop. NASA; 2002. p. 3–24. (NASA CP).
Abstract: During the past decade major advances have been made regarding low noise mixers for terahertz (THz) heterodyne receivers. State of the art hot-electron-bolometer (HEB) mixers have noise temperatures close to the quantum limit and require less than a µW power from the local oscillator (LO). The technology is now at a point where the performance of a practical receiver employing such mixer, rather than the figures of merit of the mixer itself, are of major concern. We have incorporated a phonon-cooled NbN HEB mixer in a 2.5 THz heterodyne receiver and investigated the performance of the receiver. This yields important information for the development of heterodyne receivers such as GREAT (German receiver for astronomy at THz frequencies aboard SOFIA) [1] and TELIS (Terahertz limb sounder), a balloon borne heterodyne receiver for atmospheric research [2]. Both are currently under development at DLR.
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Semenov A, Hübers H-W, Engel A, Gol’tsman G. Superconducting quantum detector for far infrared astronomy. In: Wolf J, Farhoomand J, McCreight CR, editors. Far-IR, Sub-mm & MM Detector Technology Workshop. NASA; 2002. p. 3–49. (NASA CP).
Abstract: We present the concept of the superconducting quantum detector for astronomy. Response to a single absorbed photon appears due to successive formation of a normal spot and phase-slip-centres in a narrow strip carrying sub-critical supercurrent. The detector simultaneously has a moderate energy resolution and a variable cut-off wavelength depending on both the material used and operation conditions. We simulated performance of the background-limited direct detector having the 100-micrometer cut-off wavelength. Low dark count rate will allow to realise 10-21 W Hz-1/2 noise equivalent power at 4 K background radiation. The detection mechanism provides a moderate 1/20 energy resolution at 50-micrometer wavelength.
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Tarkhov M, Claudon J, Poizat JP, Korneev A, Divochiy A, Minaeva O, et al. Ultrafast reset time of superconducting single photon detectors. Appl Phys Lett. 2008;92(24):241112 (1 to 3).
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Hübers HW, Pavlov SG, Semenov AD, Tredicucci A, Köhler R, Mahler L, et al. Investigation of a 2.5 THz quantum cascade laser as local oscillator. In: Proc. 16th Int. Symp. Space Terahertz Technol. Göteborg, Sweden; 2005. 18.
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