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Deployment-Oriented Classical/Quantum coexistence in X-haul fiber link for B5G Networks

Argiris Ntanos, Dimitris Zavitsanos, Aristeidis Stathis, Giannis Giannoulis, H. Avramopoulos

Published Jan 1, 2023• 2 citations
Publisher

Abstract

Coexistence of weak coherent pulses and intense light is experimentally demonstrated in a practical 5G X-haul scenario. Acceptable QBER measurements were obtained over 5 km fiber transmission by optimizing the parameters of single-photon sender/receiver stations.
DOI
10.1364/cleo_at.2023.am3n.5

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This work demonstrates successful QKD/5G service coexistence over deployed X-Haul infrastructure, sharing10 Gb/s10 ~\text{Gb} / \mathrm{s}10 Gb/sclassical data and raw click rates of 4.3 kbps and 51.9 kbps over 22.6 km backhaul and 2.2 km fronthaul fiber links. ©2025 The Author(s)
Entanglement distribution between spatially distant nodes is crucial for advancing the development of quantum networks. Achieving large-scale, practical quantum networks by leveraging existing fiber infrastructures and commercial technologies can greatly enhance cost efficiency in real-world applications. As such, the simultaneous transmission of quantum entanglement and classical signals within a single optical fiber is becoming increasingly desirable, yet it remains challenging due to the substantial intensity disparities between single-photon-level quantum light and classical traffic. In this study, we theoretically describe and experimentally implement polarization entanglement distribution using a continuous wave pumped integrated AlGaAs Bragg reflection waveguide quantum source, coexisting with classical light in optical fiber at the telecom C-band. The characteristics of noise photons are analyzed and evaluated under different levels of classical light power. Using the BBM92 protocol for quantum key distribution, we demonstrate that temporal and spectral filtering during coincidence detection, combined with optimized source brightness, effectively influences the secure key rate and achievable distance of the system. Polarization drift is measured across various fiber paths, with 35-hour stability tests on fibers ranging up to 55 km in length. Our results can guide the initial design of optimal entanglement distribution networks that are compatible with fiber-optic communication systems.