Records |
Author |
Semenov, A. D.; Gol’tsman, G. N. |
Title |
Nonthermal mixing mechanism in a diffusion-cooled hot-electron detector |
Type |
Journal Article |
Year |
2000 |
Publication |
J. Appl. Phys. |
Abbreviated Journal |
J. Appl. Phys. |
Volume |
87 |
Issue |
1 |
Pages |
502-510 |
Keywords |
NbN HEB mixers, nonthermal |
Abstract |
We present an analysis of a diffusion-cooled hot-electron detector fabricated from clean superconducting material with low transition temperature. The distinctive feature of a clean material, i.e., material with large electron mean free path, is a relatively weak inelastic electron scattering that is not sufficient for the establishment of an elevated thermodynamic electron temperature when the detector is subjected to irradiation. We propose an athermal model of a diffusion-cooled detector that relies on suppression of the superconducting energy gap by the actual dynamic distribution of excess quasiparticles. The resistive state of the device is caused by the electric field penetrating into the superconducting bridge from metal contacts. The dependence of the penetration length on the energy gap delivers the detection mechanism. The sources of the electric noise are equilibrium fluctuations of the number of thermal quasiparticles and frequency dependent shot noise. Using material parameters typical for A1, we evaluate performance of the device in the heterodyne regime at terahertz frequencies. Estimates show that the mixer may have a noise temperature of a few quantum limits and a bandwidth of a few tens of GHz, while the required local oscillator power is in the μW range due to ineffective suppression of the energy gap by quasiparticles with high energies. |
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0021-8979 |
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1558 |
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Author |
Kroug, M.; Cherednichenko, S.; Merkel, H.; Kollberg, E.; Voronov, B.; Gol'tsman, G.; Hübers, H. W.; Richter, H. |
Title |
NbN hot electron bolometric mixers for terahertz receivers |
Type |
Journal Article |
Year |
2001 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
Volume |
11 |
Issue |
1 |
Pages |
962-965 |
Keywords |
NbN HEB mixers |
Abstract |
Sensitivity and gain bandwidth measurements of phonon-cooled NbN superconducting hot-electron bolometer mixers are presented. The best receiver noise temperatures are: 700 K at 1.6 THz and 1100 K at 2.5 THz. Parylene as an antireflection coating on silicon has been investigated and used in the optics of the receiver. The dependence of the mixer gain bandwidth (GBW) on the bias voltage has been measured. Starting from low bias voltages, close to operating conditions yielding the lowest noise temperature, the GBW increases towards higher bias voltages, up to three times the initial value. The highest measured GBW is 9 GHz within the same bias range the noise temperature increases by a factor of two. |
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312 |
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Author |
Cherednichenko, S.; Kroug, M.; Merkel, H.; Kollberg, E.; Loudkov, D.; Smirnov, K.; Voronov, B.; Gol'tsman, G.; Gershenzon, E. |
Title |
Local oscillator power requirement and saturation effects in NbN HEB mixers |
Type |
Conference Article |
Year |
2001 |
Publication |
Proc. 12th Int. Symp. Space Terahertz Technol. |
Abbreviated Journal |
Proc. 12th Int. Symp. Space Terahertz Technol. |
Volume |
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Issue |
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Pages |
273-285 |
Keywords |
NbN HEB mixers, LO power, local oscillator power, saturation effect, dynamic range |
Abstract |
The local oscillator power required for NbN hot-electron bolometric mixers (P LO ) was investigated with respect to mixer size, critical temperature and ambient temperature. P LO can be decreased by a factor of 10 as the mixer size decreases from 4×0.4 µm 2 to 0.6×0.13 µm 2 . For the smallest volume mixer the optimal local oscillator power was found to be 15 nW. We found that for such mixer no signal compression was observed up to an input signal of 2 nW which corresponds to an equivalent input load of 20,000 K. For a constant mixer volume, reduction of T c can decrease optimal local oscillator power at least by a factor of 2 without a deterioration of the receiver noise temperature. Bath temperature was found to have minor effect on the receiver characteristics. |
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San Diego, CA, USA |
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Jet Propulsion Laboratory, California Inst.it.u.t.e of Technology |
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318 |
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Hübers, H.-W.; Semenov, A. D.; Richter, H.; Schubert, J.; Hadjiloucas, S.; Bowen, J. W.; Gol'tsman, G.; Voronov, B. M.; Gershenzon, E. M. |
Title |
Antenna pattern of the quasi-optical hot-electron bolometric mixer at terahertz frequencies |
Type |
Conference Article |
Year |
2001 |
Publication |
Proc. 12th Int. Symp. Space Terahertz Technol. |
Abbreviated Journal |
Proc. 12th Int. Symp. Space Terahertz Technol. |
Volume |
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Issue |
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Pages |
286-296 |
Keywords |
NbN HEB mixers |
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San Diego, CA, USA |
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323 |
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Author |
Kawamura, J.; Tong, C.-Y. E.; Blundell, R.; Papa, D. C.; Hunter, T. R.; Patt, F.; Gol’tsman, G.; Gershenzon, E. |
Title |
Terahertz-frequency waveguide NbN hot-electron bolometer mixer |
Type |
Journal Article |
Year |
2001 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
Volume |
11 |
Issue |
1 |
Pages |
952-954 |
Keywords |
NbN HEB mixers |
Abstract |
We have developed a low-noise waveguide heterodyne receiver for operation near 1 THz using phonon-cooled NbN hot-electron bolometers. The mixer elements are submicron-sized microbridges of 4 nm-thick NbN film fabricated on a quartz substrate. Operating at a bath temperature of 4.2 K, the double-sideband receiver noise temperature is 760 K at 1.02 THz and 1100 K at 1.26 THz. The local oscillator is provided by solid-state sources, and power measured at the source is less than 1 /spl mu/W. The intermediate frequency bandwidth exceeds 2 GHz. The receiver was used to make the first ground-based heterodyne detection of a celestial spectroscopic line above 1 THz. |
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1558-2515 |
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Call Number |
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Serial |
1546 |
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