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Author Baselmans, J. J. A.; Baryshev, A.; Reker, S. F.; Hajenius, M.; Gao, J. R.; Klapwijk, T. M.; Vahtomin, Yu.; Maslennikov, S.; Antipov, S.; Voronov, B.; Gol'tsman, G. doi  openurl
  Title Direct detection effect in small volume hot electron bolometer mixers Type Journal Article
  Year 2005 Publication (up) Appl. Phys. Lett. Abbreviated Journal Appl. Phys. Lett.  
  Volume 86 Issue 16 Pages 163503 (1 to 3)  
  Keywords HEB, mixer, direct detection effect  
  Abstract We measure the direct detection effect in a small volume (0.15μm×1μm×3.5nm)(0.15μm×1μm×3.5nm) quasioptical NbN phonon cooled hot electronbolometermixer at 1.6THz1.6THz. We find that the small signal sensitivity of the receiver is underestimated by 35% due to the direct detection effect and that the optimal operating point is shifted to higher bias voltages when using calibration loads of 300K300K and 77K77K. Using a 200GHz200GHzbandpass filter at 4.2K4.2K the direct detection effect virtually disappears. This has important implications for the calibration procedure of these receivers in real telescope systems.  
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  Notes Approved no  
  Call Number Serial 377  
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Author Siddiqi, I.; Prober, D. E. url  doi
openurl 
  Title Nb–Au bilayer hot-electron bolometers for low-noise THz heterodyne detection Type Journal Article
  Year 2004 Publication (up) Applied Physics Letters Abbreviated Journal Appl. Phys. Lett.  
  Volume 84 Issue 8 Pages 1404  
  Keywords HEB, mixers, dynamic range, saturation, LO power, local oscillator power, Nb  
  Abstract The sensitivity of present Nb diffusion-cooled hot-electron bolometer (HEB) mixers is not quantum limited, and can be improved by reducing the superconducting transition temperature TC. Lowering TC reduces thermal fluctuations, resulting in a decrease of the mixer noise temperature TM. However, lower TC mixers have reduced dynamic range and saturate more easily due to background noise. We present 30 GHz microwave measurements on a bilayer HEB system, Nb–Au, in which TC can be tuned with Au layer thickness to obtain the maximum sensitivity for a given noise background. These measurements are intended as a guide for the optimization of THz mixers. Using a Nb–Au mixer with TC = 1.6 K, we obtain TM = 50 K with 2 nW of local oscillator (LO) power. Good mixer performance is observed over a wide range of LO power and bias voltage and such a device should not exhibit saturation in a THz receiver.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0003-6951 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 571  
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Author Tong, C.-Y.E.; Meledin, D.V.; Marrone, D.P.; Paine, S.N.; Gibson, H.; Blundell, R. url  doi
openurl 
  Title Near field vector beam measurements at 1 THz Type Journal Article
  Year 2003 Publication (up) IEEE Microw. Compon. Lett. Abbreviated Journal  
  Volume 13 Issue 6 Pages 235-237  
  Keywords HEB, mixer, waveguide, LO power, local oscillator power, saturation effect, dynamic range  
  Abstract We have performed near-field vector beam measurements at 1.03 THz to characterize and align the receiver optics of a superconducting receiver. The signal source is a harmonic generator mounted on an X-Y translation stage. We model the measured two-dimensional complex beam pattern by a fundamental Gaussian mode, from which we derive the position of the beam center, the beam radius and the direction of propagation. By performing scans in the planes separated by 400 mm, we have confirmed that our beam pattern measurements are highly reliable.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1531-1309 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number RPLAB @ lobanovyury @ Serial 574  
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Author Gao, J. R.; Hajenius, M.; Yang, Z. Q.; Baselmans, J. J. A.; Khosropanah, P.; Barends, R.; Klapwijk, T. M. url  doi
openurl 
  Title Terahertz superconducting hot electron bolometer heterodyne receivers Type Journal Article
  Year 2007 Publication (up) IEEE Trans. Appl. Supercond. Abbreviated Journal  
  Volume 17 Issue 2 Pages 252-258  
  Keywords HEB, mixer, direct detection effect  
  Abstract We highlight the progress on NbN hot electron bolometer (HEB) mixers achieved through fruitful collaboration between SRON Netherlands Institute for Space Research and Delft University of Technology, the Netherlands. This includes the best receiver noise temperatures of 700 K at 1.63 THz using a twin-slot antenna mixer and 1050 K at 2.84 THz using a spiral antenna coupled HEB mixer. The mixers are based on thin NbN films on Si and fabricated with a new contact-process and-structure. By reducing their areas HEB mixers have shown an LO power requirement as low as 30 nW. Those small HEB mixers have demonstrated equivalent sensitivity as those with large areas provided the direct detection effect due to broadband radiation is removed. To manifest that a HEB based heterodyne receiver can in practice be used at arbitrary frequencies above 2 THz, we demonstrate a 2.8 THz receiver using a THz quantum cascade laser (QCL) as local oscillator.  
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  Series Volume Series Issue Edition  
  ISSN 1051-8223 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number RPLAB @ asmirn @ Serial 557  
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Author Ryabchun, Sergey; Tong, Cheuk-Yu Edward; Blundell, Raymond; Gol'tsman, Gregory url  doi
openurl 
  Title Stabilization scheme for hot-electron bolometer receivers using microwave radiation Type Journal Article
  Year 2009 Publication (up) IEEE Trans. Appl. Supercond. Abbreviated Journal IEEE Trans. Appl. Supercond.  
  Volume 19 Issue 1 Pages 14-19  
  Keywords HEB, mixer, Allan variance, stabilization, radiometer equation  
  Abstract We present the results of a stabilization scheme for terahertz receivers based on NbN hot-electron bolometer (HEB) mixers that uses microwave radiation with a frequency much lower than the gap frequency of NbN to compensate for mixer current fluctuations. A feedback control loop, which actively controls the power level of the injected microwave radiation, has successfully been implemented to stabilize the operating point of the HEB mixer. This allows us to increase the receiver Allan time to 10 s and also improve the temperature resolution of the receiver by about 30% in the total power mode of operation.  
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  Corporate Author Thesis  
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  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1051-8223 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number RPLAB @ lobanovyury @ Serial 559  
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