Status monitoring concept for a WDM PON

We propose and demonstrate a method for simultaneous real-time status monitoring and troubleshooting of a high-capacity single-fiber bidirectional passive optical network (PON) that is based on wavelength-division-multiplexing (WDM) techniques. To avoid interference between the bidirectional traffic, downstream and upstream signals are assigned in different spectral bands. The two main parts of the monitoring and fault-diagnosis functions are a traffic-directing and amplification module and a signal-selection switch module. Using an optical time-domain reflectometer, the fault-diagnosis test path can be greater than 50 km. Tests results are presented for 10-Gb/s upstream and downstream links over 35-km distances.