Mid-infrared characterization of NbTiN superconducting nanowire single-photon detectors on silicon-on-insulator

TL;DR

This paper reports on the development of NbTiN superconducting nanowire single-photon detectors capable of detecting mid-infrared photons up to 3.5 micrometers with high efficiency, low dark counts, and fast recovery, suitable for integrated photonic applications.

Contribution

It introduces mid-infrared sensitive superconducting nanowire detectors fabricated on silicon-on-insulator, expanding their spectral range and demonstrating high performance in this regime.

Findings

Detection efficiency saturated up to 3.5 μm wavelength

Dark count rate less than 10 counts per second

Recovery time of 4.3 ns

Abstract

Superconducting nanowire single-photon detectors are widely used for detecting individual photons across various wavelengths from ultraviolet to near-infrared range. Recently, there has been increasing interest in enhancing their sensitivity to single photons in the mid-infrared spectrum, driven by applications in quantum communication, spectroscopy and astrophysics. Here, we present our efforts to expand the spectral detection capabilities of U-shaped NbTiN-based superconducting nanowire single-photon detectors, fabricated in a 2-wire configuration on a silicon-on-insulator substrate, into the mid-infrared range. We demonstrate saturated internal detection efficiency extending up to a wavelength of 3.5 {\mu}m for a 5 nm thick and 50 nm wide NbTiN nanowire with a dark count rate less than 10 counts per second at 0.9 K and a rapid recovery time of 4.3 ns. The detectors are engineered for integration on waveguides in a silicon-on-insulator platform for compact, multi-channel device applications.