Dauler, E. A., Kerman, A. J., Robinson, B. S., Yang, J. K. W., Voronov, B. M., Gol’tsman, G. N., et al. (2006). Achieving high counting rates in superconducting nanowire single-photon detectors. In CLEO/QELS (JTuD3 (1 to 2)). Optical Society of America.
Abstract: Kinetic inductance is determined to be the primary limitation to the counting rate of superconducting nanowire single-photon counters. Approaches for overcoming this limitation will be discussed.
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Rosfjord, K. M., Yang, J. K. W., Dauler, E. A., Anant, V., Berggren, K. K., Kerman, A. J., et al. (2006). Increased detection efficiencies of nanowire single-photon detectors by integration of an optical cavity and anti-reflection coating. In CLEO/QELS (JTuF2 (1 to 2)).
Abstract: We fabricate and test superconducting NbN-nanowire single-photon detectors with an integrated optical cavity and anti-reflection coating. We design the cavity and coating such as to maximize absorption in the NbN film of the detector.
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Finkel, M. I., Maslennikov, S. N., Vachtomin, Y. B., Svechnikov, S. I., Smirnov, K. V., Seleznev, V. A., et al. (2005). Hot electron bolometer mixer for 20 – 40 THz frequency range. In Proc. 16th Int. Symp. Space Terahertz Technol. (pp. 393–397). Göteborg, Sweden.
Abstract: The developed HEB mixer was based on a 5 nm thick NbN film deposited on a GaAs substrate. The active area of the film was patterned as a 30×20 μm 2 strip and coupled with a 50 Ohm coplanar line deposited in situ. An extended hemispherical germanium lens was used to focus the LO radiation on the mixer. The responsivity of the mixer was measured in a direct detection mode in the 25÷64 THz frequency range. The noise performance of the mixer and the directivity of the receiver were investigated in a heterodyne mode. A 10.6 μm wavelength CW CO 2 laser was utilized as a local oscillator.
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Jiang, L., Li, J., Zhang, W., Yao, Q. J., Lin, Z. L., Shi, S. C., et al. (2005). Characterization of NbN HEB mixers cooled by a close-cycled 4 Kelvin refrigerator. IEEE Trans. Appl. Supercond., 15(2), 511–513.
Abstract: It is quite beneficial to operate superconducting hot-electron-bolometer (HEB) mixers with a close-cycled 4 Kelvin refrigerator for real applications such as astronomy and atmospheric research. In this paper, a phononcooled NbN HEB mixer (quasioptical type) is thoroughly characterized under such a cooling circumstance. The effects of mechanical vibration, electrical interference, and temperature fluctuation of a two-stage Gifford-McMahon 4 Kelvin refrigerator upon the characteristics of the phononcooled NbN HEB mixer are investigated in particular. Detailed measurement results are presented.
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Zhang, W., Jiang, L., Lin, Z. H., Yao, Q. J., Li, J., Shi, S. C., et al. (2005). Development of a quasi-optical NbN superconducting HEB mixer. In Proc. 16th Int. Symp. Space Terahertz Technol. (pp. 209–213).
Abstract: In this paper, we report the performance of a quasi-optical NbN superconducting HEB (hot electron bolometer) mixer measured at 500 and 850GHz. The quasi-optical NbN superconducting HEB mixer is cryogenically cooled by a 4-K close-cycled refrigerator. Measured receiver noise temperature at 850 and 500GHz are 3000K and 2500K respectively with wire grid as beamsplitter, while the lowest receiver noise temperature is found to be approximately 1200K with Mylar film. The theoretical receiver noise temperature (taking into account the elliptical polarization of log-spiral antenna) is consistent with measured one. The receiver noise temperature and conversion gain with 15-μm Mylar film as the beamsplitter at 500GHz are thoroughly investigated for different LO pumping levels and dc biases. The stability of the mixer’s IF output power is also demonstrated.
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