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Semenov AD, Hübers H-W, Richter H, Smirnov K, Gol'tsman GN, Voronov BM. Superconducting hot-electron bolometer mixer for terahertz heterodyne receivers [abstract]. In: Proc. 15th Int. Symp. Space Terahertz Technol.; 2004. 164.
Abstract: A number of on-going astronomical and atmospheric research programs are aimed to the Terahertz (THz) spectral region. At frequencies above about 1.4 THz heterodyne receivers planned for these missions will use superconducting hot-electron bolometers as a mixers. We present current results on the development of superconducting NbN hot- electron bolometer mixer and quasioptical radiation coupling scheme for GREAT (German Receiver for Astronomy at Terahertz Frequencies, to be used aboard of SOFIA) and TELIS (Terahertz Limb Sounder). The mixer is incorporated into hybrid antenna consisting of a planar feed antenna, which has either logarithmic spiral or double-slot configuration, and hyperhemispherical silicon lens. For the log-spiral feed antenna, the double side-band receiver noise temperature of 5500 K was achieved at 4.3 THz. The noise temperature shows less than 3 dB increase in the intermediate frequency band from 4 GHz to 7 GHz. The hybrid antenna had almost frequency independent and symmetric radiation pattern with the beam-width slightly broader than expected for a diffraction limited pattern. Results of FTS measurements in the direct detection regime agreed with the spectral dependence of the noise temperature for spiral antennas with different spacing of inner terminals.
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Ryabchun S, Korneev A, Matvienko V, Smirnov K, Kouminov P, Seleznev V, et al. Superconducting single photon detectors array based on hot electron phenomena. In: Proc. 15th Int. Symp. Space Terahertz Technol.; 2004. p. 242–7.
Abstract: In this paper we propose to use time domain multiplexing for large format arrays of superconducting single photon detectors (SSPDs) of the terahertz, visible and infrared frequency ranges based on ultrathin superconducting NbN films. Effective realization of time domain multiplexing for SSPD arrays is possible due to a short electric pulse of the SSPD as response to radiation quantum absorption, picosecond jitter and extremely low noise equivalent power (NEP). We present experimental results of testing 2×2 arrays in the infrared waveband. The measured noise equivalent power in the infrared and expected for the terahertz waveband is 10 – 21 WHz -1/2 . The best quantum efficiency (QE) of SSPD is 50% at 1.3 µm wavelength.
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Hajenius M, Baselmans JJA, Gao JR, Klapwijk TM, de Korte 2 PAJ, Voronov B, et al. Increased bandwidth of NbN phonon cooled hot electron bolometer mixers. In: Proc. 15th Int. Symp. Space Terahertz Technol.; 2004. p. 381–6.
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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Goltsman G, Korneev A, Izbenko V, Smirnov K, Kouminov P, Voronov B, et al. Nano-structured superconducting single-photon detectors. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 2004;520(1-3):527–9.
Abstract: NbN detectors, formed into meander-type, 10×10-μm2 area structures, based on ultrathin (down to 3.5-nm thickness) and nanometer-width (down to below 100 nm) NbN films are capable of efficiently detecting and counting single photons from the ultraviolet to near-infrared optical wavelength range. Our best devices exhibit QE >15% in the visible range and ∼10% in the 1.3–1.5-μm infrared telecommunication window. The noise equivalent power (NEP) ranges from ∼10−17 W/Hz1/2 at 1.5 μm radiation to ∼10−19 W/Hz1/2 at 0.56 μm, and the dark counts are over two orders of magnitude lower than in any semiconducting competitors. The intrinsic response time is estimated to be <30 ps. Such ultrafast detector response enables a very high, GHz-rate real-time counting of single photons. Already established applications of NbN photon counters are non-invasive testing and debugging of VLSI Si CMOS circuits and quantum communications.
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Il'in K, Siegel M, Semenov A, Engel A, Hübers H-W, Hollmann E, et al. Thickness dependence of superconducting properties of ultrathin Nb and NbN films. In: AKF-Frühjahrstagung.; 2004.
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Richter H, Semenov A, Hubers H-W, Smirnov K, Gol’tsman G, Voronov B. Phonon cooled hot-electron bolometric mixer for 1-5 THz. In: Proc. 29th IRMMW / 12th THz.; 2004. p. 241–2.
Abstract: Heterodyne receivers for applications in astronomy and planetary research need quantum limited sensitivity. In instruments which are currently built for SOFIA and Herschel, superconducting hot electron bolometers (HEB) are used to achieve this goal at frequencies above 1.4 THz. In order to optimize the performance for this frequency of hot electron bolometer mixers with different in-plane dimensions and logarithmic-spiral feed antennas have been investigated. Their noise temperatures and beam patterns were measured. Above 3 THz the best performance was achieved with a superconducting bridge of 2.0/spl times/0.2 /spl mu/m/sup 2/ incorporated in a logarithmic spiral antenna. The DSB noise temperatures were 2700 K, 4700 and 6400 K at 3.1 THz, 4.3 THz and 5.2 THz, respectively. The results demonstrate that the NbN HEB is very well suited as a mixer for THz heterodyne receivers up to at least 5 THz.
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Rubtsova I, Korneev A, Matvienko V, Chulkova G, Milostnaya I, Goltsman G, et al. Spectral sensitivity, quantum efficiency, and noise equivalent power of NbN superconducting single-photon detectors in the IR range. In: Proc. 29th IRMMW / 12th THz.; 2004. p. 461–2.
Abstract: We have developed nanostructured NbN superconducting single-photon detectors capable of GHz-rate photon counting in the 0.4 to 5 /spl mu/m wavelength range. Quantum efficiency of 30%, dark count rate 3/spl times/10/sup -4/ s/sup -1/, and NEP=10/sup -20/ W/Hz/sup -1/2/ have been measured at the 1.3-/spl mu/m wavelength for the device operating at 2.0 K.
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Verevkin A, Zhang J, Pearlman A, Slysz W, Sobolewski R, Korneev A, et al. Ultimate sensitivity of superconducting single-photon detectors in the visible to infrared range.; 2004.
Abstract: We present our quantum efficiency (QE) and noise equivalent power (NEP) measurements of the meandertype ultrathin NbN superconducting single-photon detector in the visible to infrared radiation range. The nanostructured devices with 3.5-nm film thickness demonstrate QE up to~ 10% at 1.3–1.55 µm wavelength, and up to 20% in the entire visible range. The detectors are sensitive to infrared radiation with the wavelengths down to~ 10 µm. NEP of about 2× 10-18 W/Hz1/2 was obtained at 1.3 µm wavelength. Such high sensitivity together with GHz-range counting speed, make NbN photon counters very promising for efficient, ultrafast quantum communications and another applications. We discuss the origin of dark counts in our devices and their ultimate sensitivity in terms of the resistive fluctuations in our superconducting nanostructured devices.
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Slysz W, Wegrzecki M, Papis E, Gol'tsman GN, Verevkin A, Sobolewski R. A method of optimization of the NbN superconducting single-photon detector. Vol 36.; 2004.
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Slysz W, Wegrzecki M, Bar J, Grabiec P, Gol'tsman GN, Verevkin M, et al. NbN superconducting single-photon detectors coupled with a communication fiber. Vol 37.; 2004.
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