Optical Properties of Superconducting Nanowire Single-Photon Detectors

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We measured the optical absorptance of superconducting nanowire single photon detectors.

• We found that 200-nm-pitch, 50%-fill-factor devices had an average absorptance of 21% for normally-incident front-illumination of 1.55-um-wavelength light polarized parallel to the nanowires, and only 10% for perpendicularly-polarized light.
• We also measured devices with lower fill-factors and narrower wires that were five times more sensitive to parallel-polarized photons than perpendicular-polarized photons.
• We developed a numerical model that predicts the absorptance of our structures.