PT Journal
AU Gol’tsman, GN
   Okunev, O
   Chulkova, G
   Lipatov, A
   Semenov, A
   Smirnov, K
   Voronov, B
   Dzardanov, A
   Williams, C
   Sobolewski, R
TI Picosecond superconducting single-photon optical detector
SO Appl. Phys. Lett.
JI Appl. Phys. Lett.
PY 2001
BP 705
EP 707
VL 79
IS 6
DI 10.1063/1.1388868
DE NbN SSPD; SNSPD
AB We experimentally demonstrate a supercurrent-assisted, hotspot-formation mechanism for ultrafast detection and counting of visible and infrared photons. A photon-induced hotspot leads to a temporary formation of a resistive barrier across the superconducting sensor strip and results in an easily measurable voltage pulse. Subsequent hotspot healing in ∼30 ps time frame, restores the superconductivity (zero-voltage state), and the detector is ready to register another photon. Our device consists of an ultrathin, very narrow NbN strip, maintained at 4.2 K and current-biased close to the critical current. It exhibits an experimentally measured quantum efficiency of ∼20% for 0.81 μm wavelength photons and negligible dark counts.
ER