Статистика фотоотсчетов сверхпроводникового однофотонного детектора из трехслойной пленки WSi
Superconducting nanowire single-photon detectors (SNSPD) are successfully used in quantum optics, when a record-breaking time resolution, high speed and record low level of dark counts are required. However, the SNSPD detection efficiency is limited by the absorption coefficient of the radiation by the ultrathin superconducting film. One of the promising ways to increase the absorption in the detector without limiting its broadband is to make the detector in the form of several vertically stacked layers and connecting them in parallel. For the first time, we studied single-photon detection in a multilayer structure consisting of three superconducting layers of amorphous tungsten silicide (WSi) separated by thin layers of amorphous silicon. We demonstrated two modes of operation of the detector: the avalanche regime and the arm-trigger regime, and determined that the regime change occurs in the bias current range of ~0.5-0.6 of the detector superconducting critical current.