[21p-A306-1~16] 11.4 Analog applications and their related technologies

△ [21p-A306-5] Superconducting nanostrip single-photon detectors for 2 um wavelength band

〇(P)Fumihiro China¹, Satoru Mima¹, Shigehito Miki^1,2, Masahiro Yabuno¹, Shigeyuki Miyajima¹, Hirotaka Terai¹ (1.NICT, 2.Kobe Univ.)

Keywords:Superconducting nanostrip single-photon detector, Mid-infrared photon detection

In this study, we have been developing superconducting nanostrip single-photon detectors (SNSPDs) for 2 um wavelength band, which is difficult to detect photons with the semiconductor photon detectors. We designed and fabricated NbTiN-SNSPDs with a distributed Bragg reflector mirror for 2 um wavelength comprised of SiO₂/Si bilayers on Si wafer. Subsequently, we evaluated the system detection efficiency (SDE) of the fabricated SNSPDs using cryocooling systems and an optical system for 2 um wavelength. We confirmed that the internal detection efficiency of the SNSPD saturates at an operation temperature of 0.77 K, and the SNSPD achieves 89% SDE at 2 um wavelength.