Xtera holds exclusive rights in this patent, US Patent No. 6,239,902, which it says "illustrates Xtera's precedence in the development of long haul transport systems employing lumped or distributed Raman amplification on most types of NZ-DSF fibers."
Distributed Raman, which uses the transmission line fiber as the gain medium, is used by carriers to achieve greater transmission distances in long haul and ultralong haul networks. Xtera uses this patented technology in its Nu-Wave DWDM system.