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Hübers, H.-W.; Semenov, A.; Holldack, K.; Schade, U.; Wüstefeld, G.; Gol’tsman, G. |
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Title |
Time domain analysis of coherent terahertz synchrotron radiation |
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Journal Article |
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Year |
2005 |
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Appl. Phys. Lett. |
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Appl. Phys. Lett. |
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87 |
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18 |
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184103 (1 to 3) |
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NbN HEB mixers, applications |
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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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Il'in, K.; Siegel, M.; Semenov, A.; Engel, A.; Hübers, H.-W.; Hollmann, E.; Gol'tsman, G.; Voronov, B. |
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Title |
Thickness dependence of superconducting properties of ultrathin Nb and NbN films |
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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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1503 |
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Semenov, A.; Richter, H.; Hübers, H.-W.; Smirnov, K.; Voronov, B.; Gol'tsman, G. |
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Title |
Development of terahertz superconducting hot-electron bolometer mixers |
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Conference Article |
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2003 |
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Proc. 6th European Conf. Appl. Supercond. |
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Proc. 6th European Conf. Appl. Supercond. |
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181 |
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2960-2965 |
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NbN HEB mixers |
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We present recent results of the development of phonon cooled hot-electron bolometric (HEB) mixers for airborne and balloon borne terahertz heterodyne receivers. Three iomportant issues have been addresses: the quality of NbN films the HEB mixers were made from, the spectral properties of the HEB mixers and the local oscillator power required for optical operation. Studies with an atomic force microscope indicate, that the performance of the HEB mixer might have been effected by the microstructure of the NbN film. Antenna gain and noise temperature were investigated at terahertz frequencies for a HEB embedded in either log-spiral or twin-slot feed antenna. Comparison suggests that at frequencies above 3 THz the spiral feed provides better overall performance. At 1.6 THz, a power of 2.5 µW was required from the local oscillator for optimal operation of the HEB mixer. |
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Sorrento, Italy |
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0750309814, 978-0750309813 |
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1505 |
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Semenov, A. D.; Hübers, H.-W.; Richter, H.; Birk, M.; Krocka, M.; Mair, U.; Smirnov, K.; Gol'tsman, G. N.; Voronov, B. M. |
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2.5 THz heterodyne receiver with NbN hot-electron-bolometer mixer |
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2002 |
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Phys. C: Supercond. |
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Phys. C: Supercond. |
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372-376 |
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448-453 |
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NbN HEB mixers, applications |
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We describe a 2.5 THz heterodyne receiver for applications in astronomy and atmospheric research. The receiver employs a superconducting NbN phonon-cooled hot-electron-bolometer mixer and an optically pumped far-infrared gas laser as local oscillator. 2200 K double sideband mixer noise temperature was measured at 2.5 THz across a 1 GHz intermediate frequency bandwidth centred at 1.5 GHz. The total conversion losses were 17 dB. The mixer response was linear at load temperatures smaller than 400 K. The receiver was tested in the laboratory environment by measuring the methanol line in emission. Observed pressure broadening confirms the true heterodyne detection regime of the mixer. |
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0921-4534 |
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1526 |
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Hübers, H.-W.; Semenov, A.; Richter, H.; Birk, M.; Krocka, M.; Mair, U.; Smirnov, K.; Gol’tsman, G.; Voronov, B. |
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Title |
Terahertz Heterodyn Receiver with a hot-electron bolometer mixer |
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Conference Article |
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2002 |
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Far-IR, Sub-mm & MM Detector Technology Workshop |
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Far-IR, Sub-mm & MM Detector Technology Workshop |
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3-24 |
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Keywords |
NbN HEB mixers |
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During the past decade major advances have been made regarding low noise mixers for terahertz (THz) heterodyne receivers. State of the art hot-electron-bolometer (HEB) mixers have noise temperatures close to the quantum limit and require less than a µW power from the local oscillator (LO). The technology is now at a point where the performance of a practical receiver employing such mixer, rather than the figures of merit of the mixer itself, are of major concern. We have incorporated a phonon-cooled NbN HEB mixer in a 2.5 THz heterodyne receiver and investigated the performance of the receiver. This yields important information for the development of heterodyne receivers such as GREAT (German receiver for astronomy at THz frequencies aboard SOFIA) [1] and TELIS (Terahertz limb sounder), a balloon borne heterodyne receiver for atmospheric research [2]. Both are currently under development at DLR. |
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NASA |
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Wolf, U.; Farhoomand, J.; McCreight, C.R. |
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NASA CP |
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Volume: 211408 |
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1537 |
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