Physical-Layer Network Coding for VPN in TDM-PON

We experimentally demonstrate a novel optical physical-layer network coding scheme over a time-division multiplexing passive optical network. Full-duplex error-free communications between optical network units (ONUs) at 2.5 Gb/s are shown for all-optical virtual private network (VPN) applications. Compared to the conventional half-duplex communications setup, our scheme can increase the capacity by 100% with a power penalty smaller than 3 dB. Synchronization of ONUs is not required for the proposed VPN scheme.