We probe the local detection efficiency in a nanowire superconducting single-photon detector along the cross-section of the wire with a far subwavelength resolution. We experimentally find a strong variation in the local detection efficiency of the device. We demonstrate that this effect explains previously observed variations in NbN detector efficiency as a function of device geometry.
Renema, J. J., Wang, Q., Gaudio, R., Komen, I., Hoog, op 't, K. P. M., Sahin, D., ... Dood, de, M. J. A. (2015). Position-dependent local detection efficiency in a nanowire superconducting single-photon detector. Nano Letters, 15, 4541-4545. https://doi.org/10.1021/acs.nanolett.5b01103