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arXiv:2511.20868

Tungsten Germanide Single-Photon Detectors with Saturated Internal Detection Efficiency at Wavelengths up to 29 μm

Benedikt Hampel, Daniel Kuznesof, Andrew S. Mueller, Sahil R. Patel, Robert H. Hadfield, Emma E. Wollman, Matthew D. Shaw, Dirk Schwarzer, Alec M. Wodtke, Khalid Hossain, Allison V. Mis, Alexana Roshko, Richard P. Mirin, Sae Woo Nam, Varun B. Verma

physics.ins-detcond-mat.supr-conphysics.app-phphysics.opticsquant-phSubmitted Nov 25, 2025• Announced Nov 27, 2025

v1 · Nov 25, 2025 v2 · Jun 16, 2026

Abstract

Superconducting nanowire single-photon detectors (SNSPDs) are among the most sensitive single-photon detectors available and have the potential to transform fields ranging from infrared astrophysics to molecular spectroscopy. However, extending their performance into the mid-infrared spectral region - crucial for applications such as exoplanet transit spectroscopy and vibrational fingerprinting of molecules - has remained a major challenge, primarily due to material limitations and scalability constraints. Here, we report on the development of SNSPDs based on tungsten germanide, a novel material system that combines high infrared sensitivity with compatibility for large-scale fabrication. Our detectors exhibit saturated internal detection efficiency at wavelengths up to 29 $\mathrm{μm}$. This advance enables scalable, high-performance single-photon detection in a spectral region that was previously inaccessible, opening new frontiers in remote sensing, thermal imaging, environmental monitoring, molecular physics, and astronomy.

Journal reference: APL Photonics 11 (6): 066112 (2026)
DOI: 10.1063/5.0331641
Comments: 10 pages, 6 figures

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