Mid-infrared Nb<sub>4</sub>N<sub>3</sub>-based superconducting nanowire single photon detectors for wavelengths up to 10 µm
Yiming Pan, Hui Zhou, Xingyu Zhang, Huiqin Yu, Lu Zhang, Mengting Si, Hao Li, Lixing You, Zhen Wang
Abstract
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. γ-Nb 4 N 3 has a reduced N content and lower energy gap than the commonly used δ-NbN, making SNSPDs based on γ-Nb 4 N 3 film more sensitive to low energy photons. We report on a Nb 4 N 3 -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 µm wavelength region, and the device detection efficiency at 2.95 µm was measured to be 32.5%, with an uncertainty of 12.7%. Furthermore, we reduced the device geometry, and measured 3–10 µm 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 µm, respectively.