Development and evaluation of superconducting nanowire single-photon detectors with dielectric multilayers

摘要

Superconducting nanowire single-photon detectors (SSPDs or SNSPDs) are capable of detecting photon in the wide wavelength range from visible light to mid-infrared light. To achieve high detection efficiency (DE) at a certain wavelength, an appropriate optical cavity structure to enhance the optical absorptance is necessary. In this study, we have been developed and evaluated the SSPDs with dielectric multilayers (DMLs) composed of SiO_2 and TiO_2. We optimized the non-periodic DML to realize an optical absorptance of 80% or more in the target wavelength of 900 - 1100 nm. Subsequently, we fabricated NbTiN based nanowires on the DML and evaluated DE of SSPDs in detail by using supercontinuum light source. The results indicated that the measured DE is almost consistent with the dependence expected from the calculated optical absorptance of the optimized DML. In addition, we confirmed the highest DE of 81% at the wavelength of 980 nm.