Patent ID: 7269351

Claim:
A wavelength division multiplexing optical transmission system comprising: an optical loading-channel transmitter generating a plurality of un-modulated optical loading channels, wherein the optical loading channel transmitter comprises a doped-fiber laser comprising a resonator constructed as an optical loop comprising: at least one rare-earth-doped optical fiber, a periodic optical filtering apparatus for generating an optical comb comprising a plurality of separate optical loading channels from amplified optical radiation produced by the optical fiber laser, and an output apparatus for outputting from the optical loading-channel transmitter a plurality of the optical loading channels of the generated optical comb, and wherein the wavelength division multiplexing optical transmission system further comprises a pump re-cycling apparatus removing and inserting pump radiation into the resonator optical loop, and wherein the pump re-cycling apparatus has an optical transmission line with a first end coupled to said resonator optical loop for removing said pump radiation therefrom and a second end coupled to said resonator optical loop for inputting said removed pump radiation thereto, and wherein a rare-earth-doped optical fiber is located within said resonator optical loop for receiving removed said pump radiation input thereto by said second end of the transmission line of said re-cycling apparatus.