Dependence of dark count rates in superconducting single photon detectors on the filtering effect of standard single mode optical fibers

摘要

We found that background radiation limits the dark count rates of superconducting single photon detectors coupled to standard single mode optical fibers to a minimum level when the source temperature of the photons is close to 300 K. We measured this level to be 10~3cps, which was confirmed by a theoretical analysis of the background radiation influence. We also investigated the filtering-effect of cooled single mode optical fibers with different bending diameters and showed that for superconducting photon receivers with operating wavelengths below 2 urn the minimum dark count rate can be significantly decreased down to 0.1 cps.