Hot-spot relaxation time current dependence in niobium nitride waveguide-integrated superconducting nanowire single-photon detectors.

Title Hot-spot relaxation time current dependence in niobium nitride waveguide-integrated superconducting nanowire single-photon detectors.
Authors S. Ferrari; V. Kovalyuk; W. Hartmann; A. Vetter; O. Kahl; C. Lee; A. Korneev; C. Rockstuhl; G. Gol'tsman; W. Pernice
Journal Opt Express
DOI 10.1364/OE.25.008739
Abstract

We investigate how the bias current affects the hot-spot relaxation dynamics in niobium nitride. We use for this purpose a near-infrared pump-probe technique on a waveguide-integrated superconducting nanowire single-photon detector driven in the two-photon regime. We observe a strong increase in the picosecond relaxation time for higher bias currents. A minimum relaxation time of (22 ± 1)?ps is obtained when applying a bias current of 50% of the switching current at 1.7 K bath temperature. We also propose a practical approach to accurately estimate the photon detection regimes based on the reconstruction of the measured detector tomography at different bias currents and for different illumination conditions.

Citation S. Ferrari; V. Kovalyuk; W. Hartmann; A. Vetter; O. Kahl; C. Lee; A. Korneev; C. Rockstuhl; G. Gol'tsman; W. Pernice.Hot-spot relaxation time current dependence in niobium nitride waveguide-integrated superconducting nanowire single-photon detectors.. Opt Express. 2017;25(8):87398750. doi:10.1364/OE.25.008739

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