Evaluation of a superconducting nanostrip single-photon detector for 2 µm DIAL application

We present a 2 μm Differential Absorption Lidar (DIAL) system with a Superconducting Nanostrip Single-Photon Detector (SNSPD) for measuring water vapor. The SNSPD is particularly suited for DIAL applications owing to its superior characteristics such as high detection efficiency, low dark count rate, high photon count rate, and low timing jitter. In this paper, we report on the evaluation results of the System Detection Efficiency (SDE) and dark count rate of a SNSPD developed at National Institute of Information and Communications Technology and a demonstration of CO₂ measurement using a gas cell and a 2 μm tunable laser. At a detector temperature of 2.1 K, the SNSPD achieved a SDE of 70.5%. Furthermore, we directly observed the absorption spectra around the CO₂ R30 absorption line. Our results indicate that SNSPDs are a promising technology for 2 μm gas remote sensing applications.