Gap-plasmon-enhanced NbN superconducting photon detectors at single-photon level

Here, we use a novel approach to enhance the visible-light photoresponse in NbN superconducting microwire photon detectors (SMPDs) by integrating them with gap plasmon resonators (GPRs). This talk describes how we observe the plasmonic NbN SMPDs can achieve a 233-fold enhancement in the phonon-electron interaction factor (γ) compared to pristine NbN SMPDs under resonant conditions with illumination at 532 nm. The nonlinear photoresponse in the visible region is attributed to the gap-plasmon resonances that disrupt the Copper pairs that break the superconducting state to normal. In addition, an impressive detection efficiency of 98% was achieved using these plasmonic SMPDs.