Optical amplifying apparatus

摘要

An optical amplifying apparatus has a plurality of pumping sources 3-1 and 3-2 generating pumping light beams at different wavelengths, a Raman amplification medium 1 receiving the pumping light beams from the pumping sources 3-1 and 3-2 to amplify a main signal light beam by using stimulated Raman scattering phenomenon due to the pumping light beams, a rare-earth-doped optical amplification medium 2 receiving the main signal light beam amplified by the Raman amplification medium 1 to further amplify it, and a pumping light introducing means 6 introducing a part or all of a pumping light beam at a specific wavelength of the pumping light beams as a pumping light beam for the rare-earth-doped optical amplification medium 2 to the rare-earth-doped optical amplification medium 2. The optical amplifying apparatus in a smaller size and with less fluctuation in the optical output power can readily send monitoring control information irrespective of presence of the optical input power. <IMAGE>