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Tol, J. van; Brunel, L.-C.; Wylde, R. J. |
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A quasioptical transient electron spin resonance spectrometer operating at 120 and 240 GHz |
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Journal Article |
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2005 |
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Rev. Sci. Instrum. |
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Rev. Sci. Instrum. |
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76 |
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7 |
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074101 (1 to 8) |
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Schottky, noise temperature |
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A new multifrequency quasioptical electron paramagnetic resonance (EPR) spectrometer is described. The superheterodyne design with Schottky diode mixer/detectors enables fast detection with subnanosecond time resolution. Optical access makes it suitable for transient EPR (TR-EPR) at 120 and 240 GHz. These high frequencies allow for an accurate determination of small g-tensor anisotropies as are encountered in excited triplet states of organic molecules like porphyrins and fullerenes. The measured concentration sensitivity for continuous-wave (cw) EPR at 240 GHz and at room temperature without cavity is 1013 spins/cm3 (15 nM) for a 1 mT linewidth and a 1 Hz bandwidth. With a Fabry-Perot cavity and a sample volume of 30 nl, the sensitivity at 240 GHz corresponds to [approximate]3×109 spins for a 1 mT linewidth. The spectrometer's performance is illustrated with applications of transient EPR of excited triplet states of organic molecules, as well as cw EPR of nitroxide reference systems and a thin film of a colossal magnetoresistance material. |
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Actually, noise spectral density is given (3e-19 W/Hz) |
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588 |
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Shelkovnikov, A.; Grain, C.; Nguyen, C. T.; Butcher, R. J.; Amy-Klein, A.; Chardonnet, C. |
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500-Hz two-photon Ramsey fringes with a SF6 beam: towards a new frequency standard in the 30-THz spectral region |
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Journal Article |
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2001 |
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Applied Physics B: Lasers and Optics |
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Appl. Phys. B: Lasers and Optics |
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73 |
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93-98 |
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THz applications |
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485 |
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Kawamura, J.; Blundell, R.; Tong, C.-yu E.; Gol’tsman, G.; Gershenzon, E.; Voronov, B.; Cherednichenko, S. |
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Low noise NbN lattice-cooled superconducting hot-electron bolometric mixers at submillimeter wavelengths |
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Journal Article |
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1997 |
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Appl. Phys. Lett. |
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Appl. Phys. Lett. |
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70 |
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12 |
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1619-1621 |
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NbN HEB mixers |
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Lattice-cooled superconducting hot-electron bolometric mixers are used in a submillimeter-wave waveguide heterodyne receiver. The mixer elements are niobium nitride film with 3.5 nm thickness and ∼10 μm2 area. The local oscillator power for optimal performance is estimated to be 0.5 μW, and the instantaneous bandwidth is 2.2 GHz. At an intermediate frequency centered at 1.4 GHz with 200 MHz bandwidth, the double sideband receiver noise temperature is 410 K at 430 GHz. The receiver has been used to detect molecular line emission in a laboratory gas cell. |
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0003-6951 |
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1599 |
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Karpowicz, Nicholas; Lu, Xiaofei; Zhang, X.-C. |
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Title |
Terahertz gas photonics |
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Journal Article |
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2009 |
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J. Modern Opt. |
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56 |
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10 |
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1137-1150 |
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The underlying physics of the generation and detection of terahertz (THz) waves in gases are described. The THz wave generation process takes place in two steps: asymmetric gas ionization by two-frequency laser fields, followed by interaction of the ionized electron wave packets with the surrounding medium, producing an intense ‘echo' with tunable spectral content. In order to clarify the physical picture at the moment of ionization, the laser–atom interaction is treated through solution of the time-dependent Schrödinger equation, yielding an ab initio understanding of the release of the electron wave packets. The second step, where the electrons interact with the surrounding plasma is treated analytically. The resulting pressure dependence of the THz radiation is explored in detail. The THz wave detection process is shown to be the result of four-wave mixing, leading to analytical expressions of the signal obtained which allow for improved optimization of systems that exploit these effects. |
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RPLAB @ gujma @ |
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670 |
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Semenov, Alexei D.; Richter, Heiko; Hubers, Heinz-Wilhelm; Gunther, Burghardt.; Smirnov, Andrey; Il'in, Konstantin S.; Siegel, Michael; Karamarkovic, Jugoslav P. |
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Terahertz performance of integrated lens antennas with a hot-electron bolometer |
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Journal Article |
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2007 |
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IEEE Trans. Microw. Theory Techn. |
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55 |
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2 |
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239-247 |
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HEB, lens antenna |
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0018-9480 |
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538 |
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Jiang, Ling; Miao, Wei; Zhang, Wen; Li, Ning; Lin, Zhen Hui; Yao, Qi Jun; Shi, Sheng-Cai; Svechnikov, S. I.; Vakhtomin, Y. B.; Antipov, S. V.; Voronov, B. M.; Kaurova, N. S.; Gol'tsman, G. N. |
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Characterization of a quasi-optical NbN superconducting HEB mixer |
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Journal Article |
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2006 |
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IEEE Trans. Microwave Theory Techn. |
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IEEE Trans. Microwave Theory Techn. |
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54 |
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7 |
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2944-2948 |
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NbN HEB mixers |
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In this paper, the performance of a quasi-optical NbN superconducting hot-electron bolometer (HEB) mixer, cryogenically cooled by a close-cycled 4-K refrigerator, is thoroughly investigated at 300, 500, and 850 GHz. The lowest receiver noise temperatures measured at the respective three frequencies are 1400, 900, and 1350 K, which can go down to 659, 413, and 529 K, respectively, after correcting the loss and associated noise contribution of the quasi-optical system before the measured superconducting HEB mixer. The stability of the quasi-optical superconducting HEB mixer is also investigated here. The Allan variance time measured with a local oscillator pumping at 500 GHz and an IF bandwidth of 110 MHz is 1.5 s at the dc-bias voltage exhibiting the lowest noise temperature and increases to 2.5 s at a dc bias twice that voltage. |
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0018-9480 |
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1448 |
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Meledin, D. V.; Marrone, D. P.; Tong, C.-Y. E.; Gibson, H.; Blundell, R.; Paine, S. N.; Papa, D.C.; Smith, M.; Hunter, T. R.; Battat, J.; Voronov, B.; Gol'tsman, G. |
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A 1-THz superconducting hot-electron-bolometer receiver for astronomical observations |
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Journal Article |
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2004 |
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IEEE Trans. Microwave Theory Techn. |
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IEEE Trans. Microwave Theory Techn. |
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52 |
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10 |
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2338-2343 |
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NbN HEB mixer, applications |
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In this paper, we describe a superconducting hot-electron-bolometer mixer receiver developed to operate in atmospheric windows between 800-1300 GHz. The receiver uses a waveguide mixer element made of 3-4-nm-thick NbN film deposited over crystalline quartz. This mixer yields double-sideband receiver noise temperatures of 1000 K at around 1.0 THz, and 1600 K at 1.26 THz, at an IF of 3.0 GHz. The receiver was successfully tested in the laboratory using a gas cell as a spectral line test source. It is now in use on the Smithsonian Astrophysical Observatory terahertz test telescope in northern Chile. |
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0018-9480 |
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1484 |
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Gershenzon, E. M.; Il'in, V. A.; Litvak-Gorskaya, L. B.; Filonovich, S. R. |
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Character of submillimeter photoconductivity in n-lnSb |
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1979 |
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Sov. Phys. JETP |
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Sov. Phys. JETP |
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49 |
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1 |
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121-128 |
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A comprehensive investigation was made of the submillimeter photoconductivity of n -1nSb in the range of wavelengths L = 0.6-8 mm, magnetic fields H = 0-30 kOe, electric fields E = 0.01-0.5 V/cm, and temperatures T = 1.3-30 K. The kinetics of the photoconductivity processes as a function of T, E; and H is investigated. It is shown that impurity photoconductivity does exist for any degree of compensation of extremely purified n-InSb. Particular attention is paid to the hopping photoconductivity realized in strongly compensated n-1nSb (K > 0.8). |
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RPLAB @ phisix @ |
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Kawamura, Jonathan; Blundell, Raymond; Tong, C.-Y. Edward; Papa, D. Cosmo; Hunter, Todd R.; Paine, Scot.t. N.; Patt, Ferdinand; Gol'tsman, Gregory; Cherednichenko, Sergei; Voronov, Boris; Gershenzon, Eugene |
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Superconductive hot-electron bolometer mixer receiver for 800 GHz operation |
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Miscellaneous |
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2000 |
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IEEE Trans. Microwave Theory and Techniques |
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IEEE Trans. Microwave Theory and Techniques |
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48 |
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4 |
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683-689 |
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RPLAB @ s @ Kawamura_superconductivehot-electron |
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Kawamura, J.; Blundell, R.; Tong, C.-Y. E.; Papa, D. C.; Hunter, T. R.; Paine, S. N.; Patt, F.; Gol'tsman, G.; Cherednichenko, S.; Voronov, B.; Gershenzon, E. |
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Superconductive hot-electron-bolometer mixer receiver for 800-GHz operation |
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2000 |
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IEEE Trans. Microw. Theory Techn. |
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IEEE Trans. Microw. Theory Techn. |
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Volume |
48 |
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4 |
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683-689 |
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NbN HEB mixers, LO power, local oscillator power, saturation, linearity, dynamic range |
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In this paper, we describe a superconductive hot-electron-bolometer mixer receiver designed to operate in the partially transmissive 350-μm atmospheric window. The receiver employs an NbN thin-film microbridge as the mixer element, in which the main cooling mechanism of the hot electrons is through electron-phonon interaction. At a local-oscillator frequency of 808 GHz, the measured double-sideband receiver noise temperature is TRX=970 K, across a 1-GHz intermediate-frequency bandwidth centered at 1.8 GHz. We have measured the linearity of the receiver and the amount of local-oscillator power incident on the mixer for optimal operation, which is PLO≈1 μW. This receiver was used in making observations as a facility instrument at the Heinrich Hertz Telescope, Mt. Graham, AZ, during the 1998-1999 winter observing season. |
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RPLAB @ lobanovyury @ |
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573 |
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