Time resolution is one of the main characteristics of the single photon detectors besides quantum efficiency and dark count rate. We demonstrate here an ultrafast time-correlated single photon counting (TCSPC) setup consisting of a newly developed single photon counting board SPC-150NX and a superconducting NbN single photon detector with a sensitive area of 7 × 7 μm. The combination delivers a record instrument response function with a full width at half maximum of 17.8 ps and system quantum efficiency ∼15% at wavelength of 1560 nm. A calculation of the root mean square value of the timing jitter for channels with counts more than 1% of the peak value yielded about 7.6 ps. The setup has also good timing stability of the detector-TCSPC board.
It was investigated the possibility of creating NbN superconducting single-photon detectors with saturated dependence of quantum efficiency versus normalized bias current. It was shown that the saturation increases for the detectors based on finer films with a lower value of R s300 /R s20 . The decreasing of R s300 /R s20 related to increasing influence of quantum corrections to conductivity of superconductors and, in its turn, to decreasing electron diffusion coefficient. The best samples has constant value of system quantum efficiency 94% at I b /I c~0 .8 and wavelength 1310 nm.
We have found experimentally that the rise times of voltage pulses in NbN superconducting single photon detectors increase nonlinearly with increasing detector length. We fabricated superconducting single photon detectors based on NbN thin films with a meander-like sensitive region of area from 2x2 µm 2 to 11x11 µm 2 . The effect is connected with the dependence of the detector resistance, which appears after photon absorption, on its kinetic inductance and hence on detector length. This conclusion is confirmed by our calculations in the framework of the two-temperature model. _____________________________ a) Author to whom correspondence should be addressed. Electronic mail: morozov@scontel.ru
We demonstrate niobium nitride based superconducting single-photon detectors sensitive in the spectral range 452 nm -2300 nm. The system performance was tested in a real-life experiment with correlated photons generated by means of spontaneous parametric down conversion, where one of photon was in the visible range and the other was in the infrared range. We measured a signal to noise ratio as high as 4 × 10 4 in our detection setting. A photon detection efficiency as high as 64% at 1550 nm and 15 % at 2300 nm was observed. arXiv:1807.04273v2 [physics.ins-det]
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.