Demonstration and scalability analysis of all-optical virtual private network in multiple passive optical networks using ASK/FSK format

We present a scalable all-optical virtual private network (VPN) in a,two-stage passive optical network (PON) architecture to connect optical network units (ONUs) in different sub-PONs. It provides efficient access and VPN service covering a wider area. The scheme employs amplitude-shift keying/frequency-shift keying (FSK) orthogonal modulation formats, which are used for the VPN and upstream traffic at 625 Mb/s and 5 Gb/s, respectively. At the optical line terminal side, a fiber Bragg grating reflects one of the two frequency components in the FSK signal back to the ONUs in a same VPN. Using a bidirectional amplifier, the power budget and the scalability of the network are significantly improved, as evidenced by numerical analysis using the parameters in the experiment.