DWDM reach extension of a GPON to 135 km

We report the operation of a gigabit-capable passive optical network (GPON, 2.488 Gb/s downstream and 1.244 Gb/s upstream) over 135 km giving performance that is consistent with the standards of International Telecommunication Union-Telecommunications Standardization Sector (ITU-T). Advanced dense-wavelength-division-multiplexing (DWDM) equipment is used to extend the physical reach and to provide fiber gain.