Extending the sensitivity of superconducting nanowire single-photon detectors to infrared wavelengths

Superconducting nanowire single-photon detectors (SNSPDs) have long been the detector of choice for photon-counting applications in the near-infrared that demand high efficiency, high timing resolution and low dark counts. Extending the operation of these detectors to mid-infrared wavelengths above 2 µm would enable a host of applications in the fields of chemical and remote sensing, LIDAR and quantum optics. Pushing the range of these detectors deeper into the mid-infrared would also be of interest to the astronomical and dark matter communities. In this work we demonstrate long-wavelength sensitivity in SNSPDs by careful material and device optimization. We also show work towards efficient, low jitter devices in the mid-infrared.