217 km long distance photon-counting optical time-domain reflectometry based on ultra-low noise up-conversion single photon detector

TL;DR

This paper presents a photon-counting optical time-domain reflectometry system capable of detecting defects over nearly 217 km of fiber with high resolution and ultra-low noise, advancing long-distance fiber diagnostics.

Contribution

The authors introduce a novel ultra-low noise up-conversion single photon detector with long wave pump and volume Bragg grating, enabling high dynamic range and long-distance OTDR measurements.

Findings

Achieved 42.19 dB dynamic range in OTDR

Detected defects along 216.95 km fiber

Attained sub-10 cm spatial resolution

Abstract

We demonstrate a photon-counting optical time-domain reflectometry with 42.19 dB dynamic range using an ultra-low noise up-conversion single photon detector. By employing the long wave pump technique and a volume Bragg grating, we reduce the noise of our up-conversion single photon detector, and achieve a noise equivalent power of -139.7 dBm/sqrt(Hz). We perform the OTDR experiments using a fiber of length 216.95 km, and show that our system can identify defects along the entire fiber length with a distance resolution better than 10 cm in a measurement time of 13 minutes.