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| Author |
Semenov, A.; Richter, H.; Smirnov, A.; Günther, B.; Hübers, H.-W.; Il’in, K.; Siegel, M.; Gol’tsman, G.; Drakinskiy, V.; Merkel, H.; Karamarkovic, J. |
| Title |
Development of HEB mixers for GREAT and for security screening |
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Abstract |
| Year |
2007 |
Publication |
Proc. 18th Int. Symp. Space Terahertz Technol. |
Abbreviated Journal |
Proc. 18th Int. Symp. Space Terahertz Technol. |
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184 |
| Keywords |
NbN HEB mixers, GREAT |
| Abstract |
We report the study on the quasioptical coupling efficiency and the gain bandwidth of NbN hot-electron bolometer mixers developed for the 4.7 THz channel of the German receiver for Astronomy at THz-frequencies (GREAT) and for security screening at subterahertz frequencies. Radiation coupling efficiency and directive properties of integrated lens antennas with log-spiral, log-periodic and double-slot planar feeds coupled to a hot-electron bolometer were experimentally studied at frequencies from 1 THz to 6 THz and compared with simulations based on the method of moments and the physical-optics ray tracing. For all studied antennas the modeled spectral dependence of the coupling efficiency fits to the experimental data obtained with both Fourier transform spectroscopy and noise temperature measurements only if the complex impedance of the bolometer is explicitly taken into account. Our experimental data did not indicate any noticeable contribution of the quantum noise to the system noise temperature. The experimentally observed deviation of the beam pattern from the model prediction increases with frequency and is most likely due to a non- ideality of the presently used lenses. Study of the intermediate frequency mixer gain at local oscillator (LO) frequencies between 2.5 THz and 0.3 THz showed an increase of the gain bandwidth at low LO frequencies that was understood as the contribution of the direct interaction of magnetic vortices with the radiation field. We have found that the non- homogeneous hot-spot model more adequately describes variation of the intermediate frequency bandwidth with the applied local oscillator power than any of uniform mixer models. The state-of-the-day performance of the GREAT 4.7-THz channel and the 0.8-THz security scanner will be presented. |
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1420 |
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Hübers, H.-W.; Semenov, A.; Holldack, K.; Schade, U.; Wüstefeld, G.; Gol’tsman, G. |
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Time domain analysis of coherent terahertz synchrotron radiation |
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Journal Article |
| Year |
2005 |
Publication |
Appl. Phys. Lett. |
Abbreviated Journal |
Appl. Phys. Lett. |
| Volume |
87 |
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18 |
Pages |
184103 (1 to 3) |
| Keywords |
NbN HEB mixers, applications |
| 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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0003-6951 |
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1457 |
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Yagoubov, P. L.; Hoogeveen, R. W. M.; Maurellis, A. M.; Mair, U.; Krocka, M.; Wagner, G.; Birk, M.; Hiibers, H.-W.; Richter, H.; Semenov, A.; Gol'tsman, G.; Voronov, B.; Koshelets, V.; Shitov, S.; Ellison, B.; Kerridge, B.; Matheson, D.; Alderman, B.; Harman, M.; Siddans, R.; Reburn, J. |
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TELIS — development of a new balloon borne THz/submm heterodyne limb sounder |
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Conference Article |
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2003 |
Publication |
Proc. 14th Int. Symp. Space Terahertz Technol. |
Abbreviated Journal |
Proc. 14th Int. Symp. Space Terahertz Technol. |
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204-214 |
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limb-sounder, TELIS |
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We present a design concept for a new state-of-the-art balloon borne atmospheric monitor that will allow enhanced limb sounding of the Earth's atmosphere within the submillimeter and far-infrared wavelength spectral range: TELIS, TErahertz and submm LImb Sounder. The instrument is being developed by a consortium of major European institutes that includes the Space Research Organisation of the Netherlands (SRON), the Rutherford Appleton Laboratory (RAL) in the United Kingdom and the Deutschen Zentrum far Luft- und Raumfahrt (DLR) in Germany (lead institute). TELIS will utilise state-of-the-art superconducting heterodyne technology and is designed to be a compact, lightweight instrument capable of providing broad spectral coverage, high spectral resolution and long flight duration (-24 hours duration during a single flight campaign). The combination of high sensitivity and extensive flight duration will allow evaluation of the diurnal variation of key atmospheric constituents such as OH, HO,, C10, BrO together will longer lived constituents such as 0 3 , HCL and N 2 0. Furthermore, TELIS will share a common balloon platform to that of the MIPAS-B Fourier Transform Spectrometer, developed by the Institute of Meteorology and Climate research of the University of Karlsruhe, Germany. MIPAS-B will provide simultaneous and complementary spectral measurements over an extended spectral range. The combination of the TELIS and MIPAS instruments will provide atmospheric scientists with a very powerful observational tool. TELIS will serve as a testbed for new cryogenic heterodyne detection techniques, and as such it will act as a prelude to future spacebome instruments planned by the European Space Agency (ESA). |
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1499 |
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Smirnov, K. V.; Vachtomin, Yu. B.; Antipov, S. V.; Maslennikov, S. N.; Kaurova, N. S.; Drakinsky, V. N.; Voronov, B. M.; Gol'tsman, G. N.; Semenov, A. D.; Richter, H.; Hubers, H.-W. |
| Title |
Noise and gain performance of spiral antenna coupled HEB mixers at 0.7 THz and 2.5 THz |
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Conference Article |
| Year |
2003 |
Publication |
Proc. 14th Int. Symp. Space Terahertz Technol. |
Abbreviated Journal |
Proc. 14th Int. Symp. Space Terahertz Technol. |
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405-412 |
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NbN HEB mixers |
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Noise and gain performance of hot electron bolometer (HEB) mixers based on ultrathin superconducting NbN films integrated with a spiral antenna was studied. The noise temperature measurements for two samples with different active area of 3 p.m x 0.24 .tni and 1.3 1..tm x 0.12 1.tm were performed at frequencies 0.7 THz and 2.5 THz. The best receiver noise temperatures 370 K and 1600 K, respectively, have been found at these frequencies. The influence of contact resistance between the superconductor and the antenna terminals on the noise temperature of HEB is discussed. The noise and gain bandwidth of 5GHz and 4.2 GHz, respectively, are demonstrated for similar HEB mixer at 0.75 THz. |
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1502 |
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Il'in, K.; Siegel, M.; Semenov, A.; Engel, A.; Hübers, H.-W.; Hollmann, E.; Gol'tsman, G.; Voronov, B. |
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Thickness dependence of superconducting properties of ultrathin Nb and NbN films |
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Conference Article |
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2004 |
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AKF-Frühjahrstagung |
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Nb, NbN films, has potential plagiarism |
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Berlin-Adlershof |
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