Enhanced Mid-Infrared Single-Photon Detection with Antenna-Coupled Superconducting Nanowires

TL;DR

This paper introduces an antenna-coupled SNSPD architecture that significantly increases effective detection area at mid-infrared wavelengths without sacrificing efficiency or increasing dark counts, advancing scalable photon detection.

Contribution

The study demonstrates a novel antenna-coupled SNSPD design that enhances detection area and scalability for mid-infrared single-photon detection, overcoming limitations of traditional meander geometries.

Findings

15.7× increase in effective detection area at 7.4 μm wavelength

Maintains internal detection efficiency and dark-count rate

Provides a scalable alternative to conventional meander SNSPDs

Abstract

Scaling the photon-detection area of superconducting nanowire single-photon detectors (SNSPDs) has traditionally been achieved by nanowire meandering. However, material inhomogeneities and fabrication-induced defects, such as line-edge roughness, increase with nanowire length, leading to reduced internal photon-detection efficiency and elevated dark-count rates. This trade-off becomes increasingly pronounced as nanowires are scaled to sub-100 nm widths and sub-5 nm thicknesses required for mid- to far-infrared sensitivity. Here, we demonstrate an antenna-coupled SNSPD architecture that enhances the effective photon-detection area without increasing nanowire length. A crossed bowtie antenna integrated with an 80 nm-wide, 3 nm-thick WSi nanowire yields 15.7$\times$ increase in effective detection area at 7.4 $\mu$m compared to a bare nanowire of identical geometric footprint, while maintaining the same internal detection efficiency and dark-count rate. Antenna coupling improves noise-equivalent power and provides a more scalable route to increasing photon-detection area than conventional meander geometries, offering performance benefits for applications in astronomy, biological imaging, and molecular spectroscopy.