Patent ID: 7079313

Claim:
An optical amplifying apparatus comprising: a plurality of pumping sources generating pumping light beams at different wavelengths; a Raman amplification medium receiving the pumping light beams from said pumping sources to amplify a main signal light beam by using stimulated Raman scattering phenomenon due to said pumping light beams; a rare-earth-doped optical amplification medium receiving said main signal light beam amplified by said Raman amplification medium to further amplify said main signal light beam; and a pumping light introducing means introducing a part or all of a pumping light beam at a specific wavelength of said pumping light beams as a pumping light beam for said rare-earth-doped optical amplification medium to said rare-earth-doped optical amplification medium, wherein said plurality of pumping sources comprises a plurality of counterpropagating pumping sources generating counterpropagating pumping light beams at different wavelengths, and a copropagating pumping source generating a copropagating pumping light beam at a specific wavelength identical to at least one of said wavelengths of said counterpropagating pumping light beams generated by said counterpropagating pumping sources, said Raman amplification medium receives said counterpropagating pumping light beams from said counterpropagating pumping sources from one direction and receives said copropagating pumping light beam from said copropagating pumping source from another direction to amplify the main signal light beam by using stimulated Raman scattering phenomenon due to said pumping light beams from said one and said another directions, and said pumping light introducing means introduces a part or all of said counterpropagating pumping light beam at said specific wavelength of said counterpropagating pumping light beams from said counterpropagating pumping sources as a pumping light beam for said rare-earth- doped optical amplification medium to said rare-earth-doped optical amplification medium, and transmits at least said copropagating pumping light beam at said specific wavelength from said copropagating pumping source as another pumping light beam for said rare-earth-doped optical amplification medium to said rare-earth-doped optical amplification medium.