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

Optics Express. 2017. Vol. 25. No. 8. P. 8739–8750.

Ferrari S., Kovalyuk V., Hartmann W., Vetter A., Kahl O., Lee C., Корнеев А. А., Rockstuhl C., G.Gol’tsman, Pernice W.

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.

Ключевые слова: интегральная оптика, нанофотоника, сверхпроводниковый однофотонный детектор, superconducting single-photon detector, nanophotonics