Exceeding 95% system efficiency within the telecom C-band in superconducting nanowire single photon detectors

We present a single-photon detector with system detection efficiencies exceeding 95% over the wavelength range 1520-1550 nm, with polarization sensitivities in the range of 1.02-1.08. The wavelength range is tunable over 200 nm via variation of the top-two dielectric layer thicknesses.