Polarization-insensitive high-efficiency superconducting nanowire single-photon detector

Superconducting nanowire single-photon detectors (SNSPDs) struggle to balance high system detection efficiency (SDE) and low polarization dependence. This work proposes a co-design of the NbN films, α-Si anti-reflection coating (ARC), and SiO₂/Ta₂O₅ distributed Bragg reflector (DBR) to reduce the polarization-dependent optical response of the nanowires. Simulations based on rigorous coupled-wave analysis (RCWA) and the finite-element method show absorptance above 99% for both transverse-electric (TE) and transverse-magnetic (TM) polarizations and absorptance above 90% over the wavelength range from 1530 to 1640 nm. Experimentally, the device achieves 97% SDE at 1530 nm (polarization sensitivity, PS = 1.1), PS < 1.3 over 1490-1640 nm, 39.5 ns recovery time, and 63.5 ps timing jitter. Retaining a conventional single-layer meander nanowire geometry, this design unifies high efficiency and polarization insensitivity, advancing SNSPD applications in quantum communications, free-space links, and single-photon imaging.