Abstract
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.
Highlights
Optical access networks connect multiple endpoints to a common network node via shared fibre infrastructure
We have demonstrated that quantum key distribution (QKD) can be implemented in typical gigabit passive optical network (GPON) networks employing two feeder fibres between the network node and passive splitter
Two separate feeder fibres are used in conventional GPON networks for PON protection[17]
Summary
Optical access networks connect multiple endpoints to a common network node via shared fibre infrastructure. 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. 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. Realising multiplexed point-to-multipoint links critically depends on new approaches to overcome the heightened influence of Raman noise in passive networks In these networks power splitters are employed to address each user. In a dual feeder network, secure keys can be transmitted alongside full power GPON data signals without the need for post-processing[22] or time-alignment[23], making it compatible with this widespread optical access network technology. The method permits operating QKD with up to 128 users in realistic network layouts while keeping the advantage of having single fibre links in the main, multi-user part of the network
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