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Semenov, A. D., Hübers, H. - W., Schubert, J., Gol'tsman, G. N., Elantiev, A. I., Voronov, B. M., et al. (2000). Design and performance of the lattice-cooled hot-electron terahertz mixer. J. Appl. Phys., 88(11), 6758–6767.
Abstract: We present the measurements and the theoreticalmodel of the frequency-dependent noise temperature of a superconductor lattice-cooled hot-electron bolometer mixer in the terahertz frequency range. The increase of the noise temperature with frequency is a cumulative effect of the nonuniform distribution of the high-frequency current in the bolometer and the charge imbalance, which occurs at the edges of the normal domain and at the contacts with normal metal. We show that under optimal operation the fluctuation sensitivity of the mixer is determined by thermodynamic fluctuations of the noise power, whereas at small biases there appears additional noise, which is probably due to the flux flow. We propose the prescription of how to minimize the influence of the current distribution on the mixer performance.
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Kardashev, N. S., Andreyanov, V. V., Buyakas, V. I., Vinogradov, I. S., Gvamichava, A. S., Kotik, A. I., et al. (2000). The Millimetron project. In Proc. Lebedev Phys. Institute (Vol. 228).
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Sergeev, A., & Mitin, V. (2000). Electron-phonon interaction in disordered conductors: Static and vibrating scattering potentials. Phys. Rev. B., 61(9), 6041–6047.
Abstract: Employing the Keldysh diagram technique, we calculate the electron-phonon energy relaxation rate in a conductor with the vibrating and static δ-correlated random electron-scattering potentials. If the scattering potential is completely dragged by phonons, this model yields the Schmid’s result for the inelastic electron-scattering rate τ−1e−ph. At low temperatures the effective interaction decreases due to disorder, and τ−1e−ph∝T4l (l is the electron mean-free path). In the presense of the static potential, quantum interference of numerous scattering processes drastically changes the effective electron-phonon interaction. In particular, at low temperatures the interaction increases, and τ−1e−ph∝T2/l. Along with an enhancement of the interaction, which is observed in disordered metallic films and semiconducting structures at low temperatures, the suggested model allows us to explain the strong sensitivity of the electron relaxation rate to the microscopic quality of a particular film.
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Kawamura, J., Blundell, R., Tong, C. - Y. E., Papa, D. C., Hunter, T. R., Paine, S. N., et al. (2000). Superconductive hot-electron-bolometer mixer receiver for 800-GHz operation. IEEE Trans. Microw. Theory Techn., 48(4), 683–689.
Abstract: 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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Nagatsuma, T., Hirata, A., Royter, Y., Shinagawa, M., Furuta, T., Ishibashi, T., et al. (2000). A 120-GHz integrated photonic transmitter. In Proc. International topical meeting on microwave photonics (MWP 2000) (pp. 225–228).
Abstract: A photonics-based 120-GHz transmitter has been developed. A photodiode, a planar antenna and a silicon lens were integrated to form a compact millimeter-wave (MMW) emitter. The MMW signal emitted from the transmitter has been detected with a waveguide-mounted Schottky diode. The received power exceeded 100 μW, which is the highest value ever reported for photonic MMW transmitter at frequencies of >100 GHz
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