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Tanner, M. G., Natarajan, C. M., Pottapenjara, V. K., O'Connor, J. A., Warburton, R. J., Hadfield, R. H., et al. (2010). Enhanced telecom wavelength single-photon detection with NbTiN superconducting nanowires on oxidized silicon. Appl. Phys. Lett., 96(22), 3.
Abstract: Superconducting nanowire single-photon detectors (SNSPDs) have emerged as a highly promising infrared single-photon detector technology. Next-generation devices are being developed with enhanced detection efficiency (DE) at key technological wavelengths via the use of optical cavities. Furthermore, new materials and substrates are being explored for improved fabrication versatility, higher DE, and lower dark counts. We report on the practical performance of packaged NbTiN SNSPDs fabricated on oxidized silicon substrates in the wavelength range from 830 to 1700 nm. We exploit constructive interference from the SiO2/Si interface in order to achieve enhanced front-side fiber-coupled DE of 23.2 % at 1310 nm, at 1 kHz dark count rate, with 60 ps full width half maximum timing jitter.
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Yamashita, T., Miki, S., Qiu, W., Fujiwara, M., Sasaki, M., & Wang, Z. (2010). Temperature dependent performances of superconducting nanowire single-photon detectors in an ultralow-temperature region. IEEE Trans. Appl. Supercond., 21(3), 336–339.
Abstract: We report on the performance of a fiber-coupled superconducting nanowire single-photon detector (SNSPD) from 4 K down to the ultralow temperature of 16 mK for a 1550 nm wave length. The system detection efficiency (DE) increased with de creasing the temperature and reached the considerably high value of 15% with a dark count rate less than 100 cps below 1.5 K, even without an optical cavity structure. We also observed saturation of the system DE in its bias current dependency at 16 mK, which indicates that the device DE of our SNSPD nearly reached intrinsic DE despite the device having a large active area of 20 μm × 20 μm. The dark count was finite even at 16 mK and the black body radiation becomes its dominant origin in the low temperatures for fiber-coupled devices.
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Marsili, F., Najafi, F., Dauler, E., Bellei, F., Hu, X., Csete, M., et al. (2011). Single-photon detectors based on ultranarrow superconducting nanowires. Nano Lett., 11(5), 2048–2053.
Abstract: We report efficient single-photon detection (η = 20% at 1550 nm wavelength) with ultranarrow (20 and 30 nm wide) superconducting nanowires, which were shown to be more robust to constrictions and more responsive to 1550 nm wavelength photons than standard superconducting nanowire single-photon detectors, based on 90 nm wide nanowires. We also improved our understanding of the physics of superconducting nanowire avalanche photodetectors, which we used to increase the signal-to-noise ratio of ultranarrow-nanowire detectors by a factor of 4, thus relaxing the requirements on the read-out circuitry and making the devices suitable for a broader range of applications.
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Manova, N. N., Korneeva, Y. P., Korneev, A. A., Slysz, W., Voronov, B. M., & Gol'tsman, G. N. (2011). Superconducting NbN single-photon detector integrated with quarter-wave resonator. Tech. Phys. Lett., 37(5), 469–471.
Abstract: The spectral dependence of the quantum efficiency of superconducting NbN single-photon detectors integrated with quarter-wave resonators based on Si3N4, SiO2, and SiO layers has been studied.
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Yang, J. K. W., Kerman, A. J., Dauler, E. A., Cord, B., Anant, V., Molnar, R. J., et al. (2009). Suppressed critical current in superconducting nanowire single-photon detectors with high fill-factors. IEEE Trans. Appl. Supercond., 19(3), 318–322.
Abstract: In this work we present a new fabrication process that enabled the fabrication of superconducting nanowire single photon detectors SNSPD with fill-factors as high as 88% with gaps between nanowires as small as 12 nm. This fabrication process combined high-resolution electron-beam lithography with photolithography. Although this work was motivated by the potential of increased detection efficiency with higher fill-factor devices, test results showed an unexpected systematic suppression in device critical currents with increasing fill-factor.
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