Reiger, E., Pan, D., Slysz, W., Jukna, A., Sobolewski, R., Dorenbos, S., et al. (2007). Spectroscopy with nanostructured superconducting single photon detectors. IEEE J. Select. Topics Quantum Electron., 13(4), 934–943.
Abstract: Superconducting single-photon detectors (SSPDs) are nanostructured devices made from ultrathin superconducting films. They are typically operated at liquid helium temperature and exhibit high detection efficiency, in combination with very low dark counts, fast response time, and extremely low timing jitter, within a broad wavelength range from ultraviolet to mid-infrared (up to 6 mu m). SSPDs are very attractive for applications such as fiber-based telecommunication, where single-photon sensitivity and high photon-counting rates are required. We review the current state-of-the-art in the SSPD research and development, and compare the SSPD performance to the best semiconducting avalanche photodiodes and other superconducting photon detectors. Furthermore, we demonstrate that SSPDs can also be successfully implemented in photon-energy-resolving experiments. Our approach is based on the fact that the size of the hotspot, a nonsuperconducting region generated upon photon absorption, is linearly dependent on the photon energy. We introduce a statistical method, where, by measuring the SSPD system detection efficiency at different bias currents, we are able to resolve the wavelength of the incident photons with a resolution of 50 nm.
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(2007). SRON-TELIS.
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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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Ryabchun, S., Tong, C. - Y. E., Blundell, R., Kimberk, R., & Gol'tsman, G. (2007). Study of the effect of microwave radiation on the operation of HEB mixers in the terahertz frequency range. IEEE Trans. Appl. Supercond., 17(2), 391–394.
Abstract: We have investigated the effect of injecting microwave radiation, with a frequency much lower than that corresponding to the energy gap of the superconductor, on the performance of the hot-electron bolometer mixer incorporated into a THz heterodyne receiver. More specifically, we show that exposing the mixer to microwave radiation does not cause a significant rise of the receiver noise temperature and fall of the mixer conversion gain so long as the microwave power is a small fraction of local oscillator power. The injection of a small, but controlled amount of microwave power therefore enables active compensation of local oscillator power and coupling fluctuations which can significantly degrade the gain stability of hot electron bolometer mixer receivers.
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Torgashin, M. Y., Koshelets, V. P., Dmitriev, P. N., Ermakov, A. B., Filippenko, L. V., & Yagoubov, P. A. (2007). Superconducting Integrated Receiver Based on Nb-AlN-NbN-Nb Circuits. IEEE Trans. Appl. Supercond., 17(2), 379–382.
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Torgashin, M. Y., Koshelets, V. P., Dmitriev, P. N., Ermakov, A. B., Filippenko, L. V., & Yagoubov, P. A. (2007). Superconducting integrated receivers based on Nb-AlN-NbN circuits. IEEE Trans. Appl. Supercond., 17(2), 379–382.
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Koshelets, V. P., Ermakov, A. B., Filippenko, L. V., Khudchenko, A. V., Kiselev, O. S., Sobolev, A. S., et al. (2007). Superconducting integrated submillimeter receiver for TELIS. IEEE Trans. Appl. Supercond., 17(2), 336–342.
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Delacour, C., Claudon, J., Poizat, J. - P., Pannetier, B., Bouchiat, V., de Lamaestre, R. E., et al. (2007). Superconducting single photon detectors made by local oxidation with an atomic force microscope. Appl. Phys. Lett., 90(19), 191116 (1 t0 3).
Abstract: The authors present a fabrication technique of superconducting single photon detectors made by local oxidation of niobium nitride ultrathin films. Narrow superconducting meander lines are obtained by direct writing of insulating niobium oxynitride lines through the films using voltage-biased tip of an atomic force microscope. Due to the 30nm resolution of the lithographic technique, the filling factor of the meander line can be made substantially higher than detector of similar geometry made by electron beam lithography, thus leading to increased quantum efficiency. Single photon detection regime of these devices is demonstrated at 4.2K.
The authors thank J.-P. Maneval for stimulating discussions. This work has been partly supported by ACI Nanoscience from French Ministry of Research, D.G.A., by Grant No. 02.445.11.7434 of Russian Ministry of Education and Science, and by the European Commission under project “SINPHONIA,” Contract No. NMP4-CT-2005-16433.
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Koch, M. (2007). Terahertz communications: a 2020 vision. In NATO Security through Science Series (Vol. 2007, pp. 325–338).
Abstract: We discuss basic considerations for potential short-range THz communication systems which may replace or supplement present WLAN systems in 10–15 years from now. On the basis of a few fundamental estimations we show that such a system will need a line-of-sight connection between receiver and emitter. To circumvent the blocking of the direct line-of-sight connection indoor THz communication systems will also have to rely on non-line-of-sight paths which involve reflections off the walls. The reflectivity of the walls can be enhanced by dielectric mirrors. This new scheme makes steerable high-gain antennas a necessity. Hence, a wireless THz communication system can not be a simple extension of the existing technology of today's local area networks. Instead it involves completely new concepts and ideas that have not yet been worked upon.
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Semenov, A. D., Richter, H., Hubers, H. - W., Gunther, B., Smirnov, A., Il'in, K. S., et al. (2007). Terahertz performance of integrated lens antennas with a hot-electron bolometer. IEEE Trans. Microw. Theory Techn., 55(2), 239–247.
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