Fröhlich Bernd, Dynes James F, Lucamarini Marco, Sharpe Andrew W, Tam Simon W-B, Yuan Zhiliang, Shields Andrew J
Toshiba Research Europe Ltd, 208 Cambridge Science Park, Cambridge CB4 0GZ, UK.
Sci Rep. 2015 Dec 14;5:18121. doi: 10.1038/srep18121.
Optical access networks connect multiple endpoints to a common network node via shared fibre infrastructure. They will play a vital role to scale up the number of users in quantum key distribution (QKD) networks. However, the presence of power splitters in the commonly used passive network architecture makes successful transmission of weak quantum signals challenging. This is especially true if QKD and data signals are multiplexed in the passive network. The splitter introduces an imbalance between quantum signal and Raman noise, which can prevent the recovery of the quantum signal completely. Here we introduce a method to overcome this limitation and demonstrate coexistence of multi-user QKD and full power data traffic from a gigabit passive optical network (GPON) for the first time. The dual feeder implementation is compatible with standard GPON architectures and can support up to 128 users, highlighting that quantum protected GPON networks could be commonplace in the future.
光接入网络通过共享光纤基础设施将多个端点连接到一个公共网络节点。它们在扩大量子密钥分发（QKD）网络中的用户数量方面将发挥至关重要的作用。然而，常用的无源网络架构中光分路器的存在使得微弱量子信号的成功传输具有挑战性。如果在无源网络中对QKD和数据信号进行复用，情况尤其如此。光分路器会在量子信号和拉曼噪声之间引入不平衡，这可能会完全阻止量子信号的恢复。在此，我们介绍一种克服这一限制的方法，并首次展示了多用户QKD与来自千兆无源光网络（GPON）的全功率数据流量的共存。双馈线实现与标准GPON架构兼容，并且可以支持多达128个用户，这突出表明量子保护的GPON网络在未来可能会很常见。
