Superconducting single photon detectors with minimized polarization dependence

Abstract

Superconducting single photon detectors are usually fabricated in such a way that a polarization dependence of the quantum efficiency is inevitable. Their meandering nanowire leads to a preferential polarization absorption, this is undesired in experiments where the polarization degree of freedom is used. We have designed two new geometries for which the polarization dependence is minimized: a detector with two meander-type parts oriented perpendicular with respect to each other and a spiraling detector. Focusing on individual parts of the detectors shows polarization dependent quantum efficiency. When the detectors are illuminated uniformly, the maximum polarization dependent quantum efficiency cannot be achieved, however, the polarization dependence of the quantum efficiency is minimized.