Superconducting microstrip single-photon detector with system detection efficiency over 90% at 1550 nm

TL;DR

This paper presents a superconducting microstrip single-photon detector with over 90% efficiency at 1550 nm, demonstrating high performance and practical advantages over traditional SNSPDs, including high efficiency, low jitter, and operation at higher temperatures.

Contribution

The study introduces a NbN SMSPD with high detection efficiency, low dark counts, and polarization sensitivity, advancing the development of practical, large-area superconducting single-photon detectors.

Findings

Saturated system detection efficiency of ~92.2% at 1550 nm

Minimum timing jitter of ~48 ps

Over 70% efficiency at 2.1 K operation

Abstract

Generally, a superconducting nanowire single-photon detector (SNSPD) is composed of wires with a typical width of ~100 nm. Recent studies have found that superconducting strips with a micrometer-scale width can also detect single photons. Compared with the SNSPD, the superconducting microstrip single-photon detector (SMSPD) has smaller kinetic inductance, higher working current, and lower requirement in fabrication accuracy, providing potential applications in the development of ultra-large active area detectors. However, the study on SMSPD is still in its infancy, and the realization of its high-performance and practical use remains an opening question. This study demonstrates a NbN SMSPD with a saturated system detection efficiency (SDE) of ~92.2% at a dark count rate of ~200 cps, a polarization sensitivity of ~1.03, and a minimum timing jitter of ~48 ps, at the telecom wavelength of 1550 nm when coupled with a single mode fiber and operated at 0.84 K. Furthermore, the detector's SDE is over 70% when operated at a 2.1-K closed-cycle cryocooler.