An essential requirement for deploying Quantum Key Distribution (QKD) in real-world Optical Transport Networks (OTNs) is the co-propagation of quantum and classical channels over the same fibre infrastructure. Within the ALLEGRO project (Horizon Europe GA ID: 101092766), we are actively investigating the multiplexing of quantum channels—specifically BB84-based QKD—with auxiliary and third-party classical optical channels. 📡💡
🔍 Why is this important?
Multiplexing is key to scaling QKD without building new fibre networks. However, the main challenge lies in mitigating Raman scattering, where intense classical signals (~70 dB stronger than quantum signals) generate noise photons that can swamp the fragile quantum states.
📈 Our approach:
We explore spectral separation by placing the quantum channel in the O-band (1310 nm) while classical traffic remains in the C-band (1530–1565 nm). This helps reduce noise but introduces trade-offs like higher attenuation and limited component availability.
🔧 The ALLEGRO consortium is pushing forward with experimental setups (see schematic below) to evaluate and optimize this co-existence strategy, paving the way for more robust, scalable, and industry-compatible QKD solutions.
➡️ Stay tuned as we bring quantum-secured communication closer to mainstream telecom infrastructure.
#QuantumSecurity #QKD #OpticalNetworks #HorizonEurope #ALLEGROProject #QuantumCommunication #CyberSecurity #BB84 #Photonics #Multiplexing #DPO #QuantumTech
