Characterization of NbTiN-Based Superconducting Nanowire Single-Photon Detectors on Si Waveguide

We have fabricated and characterized a niobium titanium nitride (NbTiN)-based superconducting nanowire single- photon detector (SSPD or SNSPD) on the silicon (Si) waveguide toward the realization of waveguide-coupled SSPD. The superconducting critical temperature and critical current were 7.85 K and 34.4 μA at 0.3 K, respectively. We investigated the optical response of the fabricated device and found that the device exhibited a single-photon response. Furthermore, the fabricated device showed a clear bias current dependence of the output counts similar to conventional SSPDs.