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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. |
Title |
A 1-THz superconducting hot-electron-bolometer receiver for astronomical observations |
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Journal Article |
Year |
2004 |
Publication ![sorted by Publication field, ascending order (up)](img/sort_asc.gif) |
IEEE Trans. Microwave Theory Techn. |
Abbreviated Journal |
IEEE Trans. Microwave Theory Techn. |
Volume |
52 |
Issue |
10 |
Pages |
2338-2343 |
Keywords |
NbN HEB mixer, applications |
Abstract |
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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Author |
Hoeffgen, S.K.; Kuhnhenn, J.; Weinand, U. |
Title |
High radiation sensitivity of chiral long period gratings |
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Journal Article |
Year |
2010 |
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IEEE Trans. Nucl. Sci. |
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Volume |
57 |
Issue |
5 |
Pages |
2915 - 2922 |
Keywords |
chiral fiber gratings, chiral gratings, chiral LPG, from chiralphotonics |
Abstract |
The radiation sensitivity of chiral long period gratings was investigated for the first time. After a Co-60 gamma dose of 100 kGy they show radiation-induced changes of their transmission dip wavelength of up to 10 nm, which is 100 to 1000 times higher than the radiation-induced wavelength shift of different fiber Bragg grating types. They can therefore be used as radiation sensors down to doses of 10 Gy or even below, but not for accurate dose measurements since the size of the wavelength shift after a certain dose still depends on the radiation dose rate. Chiral gratings made of eight single mode fiber types with differences of their radiation-induced attenuation of several orders of magnitude were investigated in order to look for a correlation between dip wavelength shift and fiber attenuation. However, the dip wavelength curves do not show exactly the same order as the fiber attenuation curves. A theory that can exactly predict all properties of the chiral gratings might enable us to specify from our results an optimized fiber for the production of gratings that can also be used for radiation dosimetry. |
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848 |
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Baksheeva, K.; Ozhegov, R.; Goltsman, G.; Kinev, N.; Koshelets, V.; Kochnev, A.; Betzalel, N.; Puzenko, A.; Ben Ishai, P.; Feldman, Y. |
Title |
The sub THz emission of the human body under physiological stress |
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Journal Article |
Year |
2021 |
Publication ![sorted by Publication field, ascending order (up)](img/sort_asc.gif) |
IEEE Trans. Terahertz Sci. Technol. |
Abbreviated Journal |
IEEE Trans. Terahertz Sci. Technol. |
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skin sub-THz emission, medicine |
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We present evidence that in the sub-THz frequency band, human skin can be considered as an electromagnetic bio-metamaterial, in that its natural emission is a product of skin tissue geometry and embedded structures. Radiometry was performed on 32 human subjects from 480 to 700 GHz. Concurrently, the subjects were exposed to stress, while heart pulse rate (PS) and galvanic skin response (GSR) were also measured. The results are substantially different from the expected black body radiation signal of the skin surface. PS and GSR correlate to the emissivity. Using a simulation model for the skin, we find that the sweat duct is a critical element. The simulated frequency spectra qualitatively match the measured emission spectra and show that our sub-THz emission is modulated by our level of mental stress. This opens avenues for the remote monitoring of the human state. |
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9380570 |
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1259 |
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Krause, S.; Mityashkin, V.; Antipov, S.; Gol’tsman, G.; Meledin, D.; Desmaris, V.; Belitsky, V.; Rudziński, M. |
Title |
Reduction of phonon escape time for nbn hot electron bolometers by using gan buffer layers |
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Journal Article |
Year |
2017 |
Publication ![sorted by Publication field, ascending order (up)](img/sort_asc.gif) |
IEEE Trans. Terahertz Sci. Technol. |
Abbreviated Journal |
IEEE Trans. Terahertz Sci. Technol. |
Volume |
7 |
Issue |
1 |
Pages |
53-59 |
Keywords |
NbN HEB mixer |
Abstract |
In this paper, we investigated the influence of the GaN buffer layer on the phonon escape time of phonon-cooled hot electron bolometers (HEBs) based on NbN material and compared our findings to conventionally employed Si substrate. The presented experimental setup and operation of the HEB close to the critical temperature of the NbN film allowed for the extraction of phonon escape time in a simplified manner. Two independent experiments were performed at GARD/Chalmers and MSPU on a similar experimental setup at frequencies of approximately 180 and 140 GHz, respectively, and have shown reproducible and consistent results. By fitting the normalized IF measurement data to the heat balance equations, the escape time as a fitting parameter has been deduced and amounts to 45 ps for the HEB based on Si substrate as in contrast to a significantly reduced escape time of 18 ps for the HEB utilizing the GaN buffer layer under the assumption that no additional electron diffusion has taken place. This study indicates a high phonon transmissivity of the NbN-to-GaN interface and a prospective increase of IF bandwidth for HEB made of NbN on GaN buffer layers, which is desirable for future THz HEB heterodyne receivers. |
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2156-3446 |
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1330 |
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Shurakov, A.; Tong, Cheuk-yu E.; Grimes, P.; Blundell, R.; Golt'sman, G. |
Title |
A microwave reflection readout scheme for hot electron bolometric direct detector |
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Journal Article |
Year |
2015 |
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IEEE Trans. THz Sci. Technol. |
Abbreviated Journal |
IEEE Trans. THz Sci. Technol. |
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5 |
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Pages |
81-84 |
Keywords |
HEB detectors |
Abstract |
In this paper, we propose and present data from a fast THz detector based on the repurpose of hot electron bolometer mixers (HEB) fabricated from superconducting NbN thinfilm. This detector is essentially a traditional NbN bolometer element that operates under the influence of a microwave pump. The in-jected microwave power serves the dual purpose of enhancing the detector sensitivity and reading out the impedance changes of the device in response to incidentTHz radiation. We have measured an optical Noise Equivalent Power of 4 pW/ Hz for our detector at a bath temperature of 4.2 K. The measurement frequency was 0.83 THz and the modulation frequency was 1.48 kHz. The readout
scheme is versatile and facilitates both high-speed operation as well as multi-pixel applications. |
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RPLAB @ atomics90 @ |
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950 |
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