Single photon detection up to 2 um in pair of parallel microstrips based on NbRe ultrathin films

TL;DR

This paper demonstrates the successful operation of NbRe superconducting microstrip single-photon detectors at wavelengths up to 2 micrometers, expanding their applicability beyond traditional telecommunication wavelengths.

Contribution

It introduces a novel parallel microstrip design using NbRe ultrathin films capable of detecting single photons at 1.55 and 2 um, with potential for large-area detection without compromising speed.

Findings

Single-photon detection at 2 um achieved.

Device design allows large sensitive areas.

Performance explained by hot-spot two-temperature model.

Abstract

Superconducting Microstrip Single Photon Detectors (SMSPDs) are increasingly attracting the interest of the scientific community as a new platform for large area detectors with unprecedented advantaged in terms of fabrication. However, while their operativity at the telecommunication wavelength was achieved, working beyond 1.55 um is challenging. Here, we experimentally demonstrate single-photon operation of NbRe microstrips at wavelengths of 1.55 and 2 um. The devices are structured as pairs of parallel microstrips with widths ranging from 1.4 to 2.2 um and lengths from 5 to 10 um. This innovative design may assure large sensitive areas, without affecting the kinetic inductance, namely the time performance of the detectors. The results are discussed in the framework of the hot-spot two-temperature model.