Flexible and Concurrent All-Optical VPN in OFDMA PON

We propose and experimentally demonstrate a new scheme to support an all-optical virtual private network (VPN) in orthogonal frequency-division multiple-access passive optical networks (OFDMA PONs). In our scheme, VPN communications among optical network units (ONUs) are concurrent, where each ONU can simultaneously transmit/receive different VPN traffic to/from other ONUs. Therefore, VPN communications between any two ONUs can be achieved at any time. The bit rates of VPN traffic can be also flexibly adjusted by using dynamic OFDM subcarrier-allocation technique. The proposed scheme is experimentally demonstrated with 5-Gb/s downlink, 2-Gb/s uplink, and 2-Gb/s VPN OFDM signals. Error-free performances are obtained for all these signals after 25-km standard single-mode fiber (SSMF) transmission.