Mid-infrared Nb4N3-based superconducting nanowire single photon detectors for wavelengths up to 10 μm

Mid-infrared (MIR) single-photon detection is emerging as an important technology for various applications. Superconducting nanowire single photon detectors (SNSPDs) fabricated with superconducting films with energy gaps of a few meV are natural broadband single-photon detectors. Recently, extending SNSPDs' operation wavelengths into the MIR region is highly attractive. gamma-Nb4N3 has a reduced N content and lower energy gap than the commonly used delta-NbN, making SNSPDs based on gamma-Nb4N3 film more sensitive to low energy photons. We report on a Nb4N3-SNSPD based on 62-nm wide nanowire, with an optical absorption enhancement design and an optimized device package for efficient ZBLAN fiber coupling and dark count filtering. The developed device has a unity intrinsic detection efficiency (IDE) in the 1.5-4 mu m wavelength region, and the device detection efficiency at 2.95 mu m was measured to be 32.5%, with an uncertainty of 12.7%. Furthermore, we reduced the device geometry, and measured 3-10 mu m photon response of a device based on 5-nm film and 42-nm nanowire, with an IDE of 95%, 81%, 40%, and 6% for 4.8, 6, 8, and 10 mu m, respectively.(c) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

Mid-infrared single-photon detection is an important technology, and superconducting nanowire single photon detectors based on gamma-Nb4N3 film are more sensitive to low energy photons and have high detection efficiency.