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Słysz W, Węgrzecki M, Bar J, Grabiec P, Gol'tsman GN, Verevkin A, et al. NbN superconducting single-photon detector coupled with a communication fiber. Elektronika : konstrukcje, technologie, zastosowania. 2005;46(6):51–2.
Abstract: We present novel superconducting single-photon detectors (SSPDs), based on ultrathin NbN films, designed for fiber-based quantum communications (lambda = 1.3 žm and 1.55 žm). For fiber-based operation, our SSPDs contain a special micromechanical construction integrated with the NbN structure, which enables efficient and mechanically very stabile fiber coupling. The detectors combine GHz counting rate, high quantum efficiency and very low level of dark counts. At 1.3 – 1.55 žm wavelength range our detector exhibits a quantum efficiency up to 10%.
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Hübers H-W, Semenov A, Holldack K, Schade U, Wüstefeld G, Gol’tsman G. Time domain analysis of coherent terahertz synchrotron radiation. Appl Phys Lett. 2005;87(18):184103 (1 to 3).
Abstract: The time structure of coherent terahertz synchrotron radiation at the electron storage ring of the Berliner Elektronensynchrotron und Speicherring Gesellschaft has been analyzed with a fast superconducting hot-electron bolometer. The emission from a single bunch of electrons was found to last ∼1500ps at frequencies around 0.4THz, which is much longer than the length of an electron bunch in the time domain (∼5ps). It is suggested that this is caused by multiple reflections at the walls of the beam line. The quadratic increase of the power with the number of electrons in the bunch as predicted for coherent synchrotron radiation and the transition from stable to bursting radiation were determined from a single storage ring fill pattern of bunches with different populations.
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Finkel MI, Maslennikov SN, Gol'tsman GN. Terahertz heterodyne receivers based on superconductive hot-electron bolometer mixers. Radiophys Quant Electron. 2005;48(10-11):859–64.
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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Koshelets VP, Dmitriev PN, Ermakov AB, Filippenko LV, Koryukin OV, Torgashin MY, et al. Integrated superconducting spectrometer for atmosphere monitoring. Radiophys. Quant. Electron.. 2005;48(10-11):844–50.
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Encrenaz T. Neutral Atmospheres of the Giant Planets: An Overview of Composition Measurements. Space Sci Rev. 2005;116(1-2):99–119.
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Datesman AM, Schultz JC, Lichtenberger AW, Golish D, Walker CK, Kooi J. Fabrication and characterization of niobium diffusion-cooled hot-electron bolometers on silicon nitride membranes. IEEE Trans. Appl. Supercond.. 2005;15(2):928–31.
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Koshelets VP, Dmitriev PN, Ermakov AB, Sobolev AS, Torgashin MY, Kurin VV, et al. Optimization of the phase-locked flux-flow oscillator for the submm integrated receiver. IEEE Trans. Appl. Supercond.. 2005;15(2):964–7.
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Koshelets VP, Shitov SV, Ermakov AB, Filippenko LV, Koryukin OV, Khudchenko AV, et al. Superconducting integrated receiver for TELIS. IEEE Trans. Appl. Supercond.. 2005;15(2):960–3.
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Baselmans JJA, Hajenius M, Gao JR, Baryshev A, Kooi J, Klapwijk TM, et al. NbN hot electron bolometer mixers: sensitivity, LO power, direct detection and stability. IEEE Trans Appl Supercond. 2005;15(2):484–9.
Abstract: We demonstrate that the performance of NbN lattice cooled hot electron bolometer mixers depends strongly on the interface quality between the bolometer and the contact structure. Both the receiver noise temperature and the gain bandwidth can be improved by a factor of 2 by cleaning the interface and adding an additional superconducting interlayer to the contact pad. Using this we obtain a double sideband receiver noise temperature of 950 K at 2.5 THz and 4.3 K, using a 0.4/spl times/4 /spl mu/m HEB mixer with a spiral antenna. At the same bias point, we obtain an IF gain bandwidth of 6 GHz. To comply with current demands on THz mixers for use in space based receivers we reduce the device size to 0.15/spl times/1 /spl mu/m and use a twin slot antenna. We report measurements of the noise temperature, LO power requirement, stability and the direct detection effect, using a mixer with a 1.6 THz twin slot antenna and a 1.462 THz solid state LO source with calibrated output power.
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Hajenius M, Barends R, Gao JR, Klapwijk TM, Baselmans JJA, Baryshev A, et al. Local resistivity and the current-voltage characteristics of hot electron bolometer mixers. IEEE Trans Appl Supercond. 2005;15(2):495–8.
Abstract: Hot-electron bolometer devices, used successfully in low noise heterodyne mixing at frequencies up to 2.5 THz, have been analyzed. A distributed temperature numerical model of the NbN bridge, based on a local electron and a phonon temperature, is used to model pumped IV curves and understand the physical conditions during the mixing process. We argue that the mixing is predominantly due to the strongly temperature dependent local resistivity of the NbN. Experimentally we identify the origins of different transition temperatures in a real HEB device, suggesting the importance of the intrinsic resistive transition of the superconducting bridge in the modeling.
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