Optical time domain reflectometry with low noise waveguide-coupled superconducting nanowire single-photon detectors

TL;DR

This paper presents a highly sensitive optical time domain reflectometry system using integrated superconducting nanowire detectors, achieving high resolution and low noise over long fiber spans for defect detection.

Contribution

It introduces a compact, low-noise superconducting detector integrated with waveguides, enabling improved optical time domain reflectometry performance over long distances.

Findings

Achieved 50 ps timing resolution.

Dark count rate of 3 Hz.

Effective defect detection over 200 km fiber.

Abstract

We demonstrate optical time domain reflectometry over 200 km of optical fiber using low-noise NbTiN superconducting single-photon detectors integrated with Si3N4 waveguides. Our small detector footprint enables high timing resolution of 50ps and a dark count rate of 3 Hz with unshielded fibers, allowing for identification of defects along the fiber over a dynamic range of 37.4 dB. Photons scattered and reflected back from the fiber under test can be detected in free-running mode without showing dead zones or other impairments often encountered in semiconductor photon-counting optical time domain reflectometers.