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Meledin, D., Tong, C. - Y. E., Blundell, R., & Goltsman, G. (2003). Measurement of intermediate frequency bandwidth of hot electron bolometer mixers at terahertz frequency range. IEEE Microw. Wireless Compon. Lett., 13(11), 493–495.
Abstract: We have developed a new experimental setup for measuring the IF bandwidth of superconducting hot electron bolometer mixers. In our measurement system we use a chopped hot filament as a broadband signal source, and can perform a high-speed IF scan with no loss of accuracy when compared to coherent methods. Using this technique we have measured the 3 dB IF bandwidth of hot electron bolometer mixers, designed for THz frequency operation, and made from 3-4 nm thick NbN film deposited on an MgO buffer layer over crystalline quartz.
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Tong, C. E., Blundell, R., Papa, D. C., Smith, M., Kawamura, J., Gol'tsman, G., et al. (1999). An all solid-state superconducting heterodyne receiver at terahertz frequencies. IEEE Microw. Guid. Wave Lett., 9(9), 366–368.
Abstract: A superconducting hot-electron bolometer mixer-receiver operating from 1 to 1.26 THz has been developed. This heterodyne receiver employs two solid-state local oscillators each consisting of a Gunn oscillator followed by two stages of varactor frequency multiplication. The measured receiver noise temperature is 1350 K at 1.035 THz and 2700 K at 1.26 THz. This receiver demonstrates that tunable solid-state local oscillators, supplying only a few micro-watts of output power, can be used in terahertz receiver applications.
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0kunev, 0., Dzardanov, A., Ekstrom, H., Jacobsson, S., Kollberg, E., Gol'tsman, G., et al. (1994). NbN hot electron waveguide mixer for 100 GHz operation. In Proc. 5th Int. Symp. Space Terahertz Technol. (pp. 214–224).
Abstract: NbN is a promising superconducting material used to develope hot- electron superconducting mixers with an IF bandwidth over 1 GHz. In the 100 GHz frequency range, the following parameters were obtained for NbN films 50 A thick: the noise temperature of the receiver (DSB) 1000 K; the conversion losses 10 d13, the IF bandwidth 1 GHz; the local oscillator power 1 /LW. An increase of NbN film thickness up to 80-100 A and increase of working temperature up to 7-8 K, and a better mixer matching may allow to broader the IF band up to 3 Gllz, to reduce the conversion losses down to 3-5 dB and the noise tempera- ture down to 200-300 K.
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Ryabchun, S., Tong, C. -yu E., Blundell, R., Kimberk, R., & Gol’tsman, G. (2007). Stabilisation of a terahertz hot-electron bolometer mixer with microwave feedback control. In Proc. 18th Int. Symp. Space Terahertz Technol. (pp. 193–198).
Abstract: We report on implementation of microwave feedback control loop to stabilise the performance of an HEB mixer receiver. It is shown that the receiver sensitivity increases by a factor of 4 over a 16-minute scan, and the corresponding Allan time increases up to 10 seconds, as opposed to an open loop value of 1 second. Our experiments also demonstrate that the receiver sensitivity is limited by the intermediate frequency chain.
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Smirnov, A. V., Karmantsov, M. S., Smirnov, K. V., Vakhtomin, Y. B., Masterov, D. V., Tarkhov, M. A., et al. (2012). Terahertz response of thin-film YBCO bolometers. Tech. Phys., 57(12), 1716–1719.
Abstract: The bolometric response of high-temperature thin-film YBCO superconducting detectors to an electromagnetic radiation with a frequency of 2.5 THz is measured for the first time. The minimum value of the noise-equivalent power of the detectors is 3.5 × 10−9 W/Hz−−−√. The feasibility of further increasing the sensitivity of the detectors is discussed.
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Смирнов, А. В., Карманцов, М. С., Смирнов, К. В., Вахтомин, Ю. Б., Мастеров, Д. В., Тархов, М. А., et al. (2012). Терагерцовый отклик болометров на основе тонких пленок YBCO. ЖТФ, 82(12), 108–111.
Abstract: Представлены первые результаты измерения болометрического отклика высокотемпературных сверхпроводниковых детекторов на основе тонких пленок YBCO на электромагнитное излучение с частотой 2.5 THz. Минимальное значение оптической мощности, эквивалентной шуму созданных детекторов, составило 3.5· 10-9 W/sqrt(Hz)sqrt. Обсуждена возможность дальнейшего увеличения чувствительности исследуемых детекторов.
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Zorin, M., Lindgren, M., Danerud, M., Karasik, B., Winkler, D., Gol'tsman, G., et al. (1995). Nonequilibrium and bolometric responses of YBaCuO thin films to high-frequency modulated laser radiation. J. Supercond., 8(1), 11–15.
Abstract: Picosecond nonequilibrium and slow bolometric responses to infrared radiation from a patterned high-T c superconducting (HTS) film in resistive and normal states deposited onto LaAlO3, NdGaO3, and MgO substrates were investigated using both pulse and modulation techniques. The response time of 35 ps to a laser pulse of 17 ps FWHM has been observed. The intrinsic response time of the fast process is expected to be about a few picoseconds. The modulation technique, being free from the disadvantages of pulse methods (poor sensitivity, limited dynamic range), makes the detailed study of a number of relaxation processes possible. Besides the nonequilibrium response, two kinds of bolometric processes, namely phonon transport through the film-substrate interface and phonon thermal diffusion in a substrate, manifest themselves in certain frequency dependences.
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Gershenzon, E. M., Gol'tsman, G. N., Zorin, M. A., Karasik, B. S., & Trifonov, V. A. (1994). Nonequilibrium and bolometric response of YBaCuO films in a resistive state to infrared low intensity radiation. In Council on Low-temp. Phys. (pp. 82–83).
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Gershenzon, E. M., Gershenzon, M. E., Gol'tsman, G. N., Karasik, B. S., Semenov, A. D., & Sergeev, A. V. (1987). Light-induced heating of electrons and the time of the inelastic electron-phonon scattering in the YBaCuO compound. JETP Lett., 46(6), 285–287.
Abstract: For the first time, measurements have been made on the electron energy relaxation time due to the electron--phonon interaction in films of the YBaCuO superconductor. The results indicate a significant intensification of the electron--phonon interaction in this compound as compared with normal superconducting metals.
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Danerud, M., Winkler, D., Lindgren, M., Zorin, M., Trifonov, V., Karasik, B. S., et al. (1994). Nonequilibrium and bolometric photoresponse in patterned YBa2Cu3O7−δ thin films. J. Appl. Phys., 76(3), 1902–1909.
Abstract: Epitaxial laser deposited YBa2Cu3O7−δ films of ∼50 nm thickness were patterned into detectors consisting of ten parallel 1 μm wide strips in order to study nonequilibrium and bolometric effects. Typically, the patterned samples had critical temperatures around 86 K, transition widths around 2 K and critical current densities above 1×106A/cm2 at 77 K. Pulsed laser measurements at 0.8 μm wavelength (17 ps full width at half maximum) showed a ∼30 ps response, attributed to electron heating, followed by a slower bolometric decay. Amplitude modulation in the band fmod=100 kHz–10 GHz of a laser with wavelength λ=0.8 μm showed two different thermal relaxations in the photoresponse. Phonon escape from the film (∼3 ns) is the limiting process, followed by heat diffusion in the substrate. Similar relaxations were also seen for λ=10.6 μm. The photoresponse measurements were made with the film in the resistive state and extended into the normal state. These states were created by supercritical bias currents. Measurements between 75 and 95 K (i.e., from below to above Tc) showed that the photoresponse was proportional to dR/dT for fmod=1 MHz and 4 GHz. The fast response is limited by the electron‐phonon scattering time, estimated to 1.8 ps from experimental data. The responsivity both at 0.8 and 10.6 μm wavelength was ∼1.2 V/W at fmod=1 GHz and the noise equivalent power was calculated to 1.5×10−9 WHz−1/2 for the fast response.
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