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Author Gousev, Yu. P.; Olsson, H. K.; Gol'tsman, G. N.; Voronov, B. M.; Gershenzon, E. M.
Title NbN hot-electron mixer at radiation frequencies between 0.9 THz and 1.2 THz Type (up) Conference Article
Year 1998 Publication Proc. 9th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 9th Int. Symp. Space Terahertz Technol.
Volume Issue Pages 121-129
Keywords NbN HEB mixers
Abstract We report on noise temperature measurements for a NbN phonon-cooled hot-electron mixer at radiation frequencies between 0.9 THz and 1.2 THz. Radiation was coupled to the mixer, placed in a vacuum chamber of He cryostat, by means of a planar spiral antenna and a Si immersion lens. A backward-wave oscillator, tunable throughout the spectral range, delivered an output power of few 1.1W that was enough for optimum operation of the mixer. At 4.2 K ambient temperature and 1.025 THz radiation frequency, we obtained a receiver noise temperature of 1550 K despite of using a relatively noisy room-temperature amplifier at the intermediate frequency port. The noise temperature was fairly constant throughout the entire operation range and for intermediate frequencies from 1 GHz to 2 GHz.
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Call Number Serial 1588
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Author Yazoubov, P.; Kroug, M.; Merkel, H.; Kollberg, E.; Gol'tsman, G.; Lipatov, A.; Svechnikov, S.; Gershenzon, E.
Title Quasioptical NbN phonon-cooled hot electron bolometric mixers with low optimal local oscillator power Type (up) Conference Article
Year 1998 Publication Proc. 9th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 9th Int. Symp. Space Terahertz Technol.
Volume Issue Pages 131-140
Keywords NbN HEB mixers
Abstract In this paper, the noise perform.ance of NIN based phonon-cooled Hot Electron Bolometric (HEB) quasioptical mixers is investigated in the 0.55-1.1 THz frequency range. The best results of the DSB noise temperature are: 500 K at 640 GHz, 600 K at 750 GHz, 850 K at 910 GHz and 1250 K at 1.1 THz. The water vapor in the signal path causes a significant contribution to the measured noise temperature around 1.1 THz. The required LO power is typically about 60 nW. The frequency response of the spiral antenna+lens system is measured using a Fourier Transform Spectrometer with the HEB operating in a detector mode.
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Notes Approved no
Call Number Serial 1589
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Author Il'in, K. S.; Cherednichenko, S. I.; Gol'tsman, G. N.; Currie, M.; Sobolewski, R.
Title Comparative study of the bandwidth of phonon-cooled NbN hot-electron bolometers in submillimeter and optical wavelength ranges Type (up) Conference Article
Year 1998 Publication Proc. 9th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 9th Int. Symp. Space Terahertz Technol.
Volume Issue Pages 323-330
Keywords NbN HEB mixers
Abstract We report the results of the bandwidth measurements of NbN hot-electron bolometers, perfomied in the terahertz frequency domain at 140 GHz and 660 GHz and in time domain in the optical range at the wavelength of 395 nm.. Our studies were done on 3.5-nm-thick NbN films evaporated on sapphire substrates and patterned into ilin-size microbridges. In order to measure the gain bandwidth, we used two identical BWOs (140 or 660 GHz), one functioning as a local oscillator and the other as a signal source. The bandwidth we achieved was 3.5-4 GHz at 4.2 K with the optimal LO and DC biases. Time-domain measurements with a resolution below 300 fs were performed using an electro-optic sampling system, in the temperature range between 4.2 K to 9 K at various values of the bias current and optical power. The obtained response time of the NbN hot-electron bolometer to —100- fs-wide Ti:sapphire laser pulses was about 27 ps, what corresponds to the 5.9 GHz gain bandwidth.
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Notes Approved no
Call Number Serial 1590
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Author Il’in, K. S.; Milostnaya, I. I.; Verevkin, A. A.; Gol’tsman, G. N.; Gershenzon, E. M.; Sobolewski, R.
Title Ultimate quantum efficiency of a superconducting hot-electron photodetector Type (up) Journal Article
Year 1998 Publication Appl. Phys. Lett. Abbreviated Journal Appl. Phys. Lett.
Volume 73 Issue 26 Pages 3938-3940
Keywords NbN SSPD, SNSPD
Abstract The quantum efficiency and current and voltage responsivities of fast hot-electron photodetectors, fabricated from superconducting NbN thin films and biased in the resistive state, have been shown to reach values of 340, 220 A/W, and 4×104 V/W,

respectively, for infrared radiation with a wavelength of 0.79 μm. The characteristics of the photodetectors are presented within the general model, based on relaxation processes in the nonequilibrium electron heating of a superconducting thin film. The observed, very high efficiency and sensitivity of the superconductor absorbing the photon are explained by the high multiplication rate of quasiparticles during the avalanche breaking of Cooper pairs.
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ISSN 0003-6951 ISBN Medium
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Notes Approved no
Call Number Serial 1579
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Author Floet, D. Wilms; Baselmans, J. J. A.; Klapwijk, T. M.; Gao, J. R.
Title Resistive transition of niobium superconducting hot-electron bolometer mixers Type (up) Journal Article
Year 1998 Publication Applied Physics Letters Abbreviated Journal Appl. Phys. Lett.
Volume 73 Issue 19 Pages 2826
Keywords HEB
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ISSN 0003-6951 ISBN Medium
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Notes Approved no
Call Number Serial 543
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