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Author Goltsman, Gregory N.; Vachtomin, Yuriy B.; Antipov, Sergey V.; Finkel, Matvey I.; Maslennikov, Sergey N.; Polyakov, Stanislav L.; Svechnikov, Sergey I.; Kaurova, Natalia S.; Grishina, Elisaveta V.; Voronov, Boris M. url  openurl
  Title Low-noise NbN phonon-cooled hot-electron bolometer mixers for terahertz heterodyne receivers Type Conference Article
  Year (down) 2005 Publication Proc. 9-th WMSCI Abbreviated Journal Proc. 9-th WMSCI  
  Volume 9 Issue Pages 154-159  
  Keywords NbN HEB mixers  
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  Corporate Author Thesis  
  Publisher International Institute of Informatics and Systemics Place of Publication Editor  
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  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 547  
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Author Baryshev, A.; Baselmans, J. J. A.; Reker, S. F.; Hajenius, M.; Gao, J. R.; Klapwijk, T. M.; Vachtomin, Yu.; Maslennikov, S.; Antipov, S.; Voronov, B.; Gol'tsman, G. url  openurl
  Title Direct detection effect in hot electron bolometer mixers Type Abstract
  Year (down) 2005 Publication Proc. 16th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 16th Int. Symp. Space Terahertz Technol.  
  Volume Issue Pages 463-464  
  Keywords NbN HEB mixers, effect of direct detection, direct detection effect  
  Abstract NbN phonon cooled hot electron bolometer (HEB) mixers are currently the most sensitive heterodyne detectors at frequencies above 1.2 THz. They combine a good sensitivity (8-15 times the quantum limit), an IF bandwidth of the order of 4-6 GHz and a wide RF bandwidth from 0.7-5.2 THz. However, for use in a space based observatory, such as Herschel, it is of vital importance that the Local Oscillator (LO) power requirement of the mixer is compatible with the low output power of present day THz LO sources. This can be achieved by reducing the mixer volume and critical current. However, the large RF bandwidth and low LO power requirement of such a mixer result in a direct detection effect, characterized by a change in the bias current of the HEB when changing the RF signal from a black body load at 300 K to one at 77 K. As a result the measured sensitivity using a 300 K and 77 K calibration load differs significantly from the small signal sensitivity relevant for astronomical observations. In this article we describe a set of dedicated experiments to characterize the direct detection effect for a small volume quasi-optical NbN phonon cooled HEB mixer. We measure the direct detection effect in a small volume (0.15 μm · 1 μm · 3.5 nm) quasi- optical NbN phonon cooled HEB mixer at 1.6 THz. We found that the small signal sensitivity of the receiver is underestimated by approximately 35% due to the direct detection effect and that the optimal operating point is shifted to higher bias voltages when using calibration loads of 300 K and 77 K. Using a 200 GHz wide band-pass filter at the 4.2 K the direct detection effect virtually disappears. Heterodyne response measurements using water vapor absorption line in a gas cell confirms the existence and a magnitude of a direct detection effect. We also propose a theoretical explanation using uniform electron heating model. This direct detection effect has important implications for the calibration procedure of these receivers in real telescope systems. We are developing Nb HEBs for a large-format, diffusion-cooled hot electron bolometer (HEB) array submillimeter camera. The goal is to produce a 64 pixel array together with the University of Arizona to be used on the HHT on Mt Graham. It is designed to detect in the 850 GHz atmospheric window. We have fabricated Nb HEBs using a new angle- deposition process, which had previously produced high quality Nb-Au bilayer HEB devices at Yale. [1] We have characterized these devices using heterodyne mixing at ~30 GHz to compare to 345 GHz tests at the University of Arizona. We can also directly compare our Nb HEB mixers to SIS mixers in this same 345 GHz system. This allows us to rigorously calibrate the system’s losses and extract the mixer noise temperature in a well characterized mixer block, before undertaking the 850 GHz system. Here we give a report on the initial devices we have fabricated and characterized. * Department of Applied Physics, Yale University ** Department of Astronomy, University of Arizona [1] Applied Physics Letters 84, Number 8; p.1404-7, Feb 23 (2004)  
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  Notes Approved no  
  Call Number Serial 1475  
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Author Vachtomin, Y. B.; Antipov, S. V.; Maslennikov, S. N.; Smirnov, K. V.; Polyakov, S. L.; Kaurova, N. S.; Grishina, E. V.; Voronov, B. M.; Gol'tsman, G. N. url  openurl
  Title Noise temperature measurements of NbN phonon-cooled hot electron bolometer mixer at 2.5 and 3.8 THz Type Conference Article
  Year (down) 2004 Publication Proc. 15th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 15th Int. Symp. Space Terahertz Technol.  
  Volume Issue Pages 236-241  
  Keywords HEB mixer, NbN, direct detection effect  
  Abstract We present the results of noise temperature measurements of NbN phonon-cooled HEB mixers based on a 3.5 nm NbN film deposited on a high-resistivity Si substrate with a 200 nm – thick MgO buffer layer. The mixer element was integrated with a log-periodic spiral antenna. The noise temperature measurements were performed at 2.5 THz and at 3.8 THz local oscillator frequencies for the 3 µm x 0.2 µm active area devices. The best uncorrected receiver noise temperatures found for these frequencies are 1300 K and 3100 K, respectively. A water vapour discharge laser was used as the LO source. We also present the results of direct detection contribution to the measured Y-factor and of a possible error of noise temperature calculation. This error was more than 8% for the mixer with in-plane dimensions of 2.4 x 0.16 µm 2 at the optimal noise temperature point. The use of a mesh filter enabled us to avoid the effect of direct detection and decrease optical losses by 0.5 dB. The paper is concluded by the investigation results of the mixer polarization response. It was shown that the polarization can differ from the circular one at 3.8 THz by more than 2 dB.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Northampton, Massachusetts, USA Editor  
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  Notes Approved no  
  Call Number Serial 344  
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Author Ozhegov, R.; Morozov, D.; Maslennikov, S.; Okunev, O.; Smirnov, K.; Gol'tsman, G. openurl 
  Title Submillimeter wave range imaging system for registering human body radiation and finding out the things covered under clothes Type Conference Article
  Year (down) 2004 Publication Proc. 3rd Int. exhibition and conf. Non-Destructive Testing Equipment and Devices Abbreviated Journal  
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  Corporate Author Thesis  
  Publisher Place of Publication Moscow Editor  
  Language Summary Language Original Title  
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  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 345  
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Author Ожегов, Р. В.; Морозов, Д. В.; Масленников, С. Н.; Смирнов, К. В.; Окунев, О. В.; Гольцман, Г. Н. openurl 
  Title Тепловизор субмиллиметрового диапазона волн для регистрации теплового излучения тела человека и обнаружения скрытых под одеждой предметов Type Conference Article
  Year (down) 2004 Publication 3-я Международная выставка и конференция Неразрушающий контроль и техническая диагностика в промышленности Abbreviated Journal  
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  Corporate Author Thesis  
  Publisher Place of Publication Москва Editor  
  Language russian Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
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  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes Duplicated as 345 Approved no  
  Call Number Serial 346  
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