| 摘要 |
PROBLEM TO BE SOLVED: To obtain a long wavelength region erbium-doped optical fiber amplifier which can be improved in amplification efficiency in a long wavelength region. SOLUTION: A long wavelength region optical fiber amplifier is provided with a rare earth doped optical fiber 203, a forward and backward directed pumping laser diode which generates pumping light, and first wavelength selection couplers (202 and 204) for supplying the pumping light of the laser diode. The amplifier is also provided with optical isolators 206 and 209 for interrupting the reverse flow of reflected signal light at the input and output terminals of the optical fiber amplifier, a feedback loop, which makes a seed beam incident on the optical fiber 203 or makes ASE incident again on the fiber 203, and second wavelength selection couplers (201 and 205) which make the seed beam incident to the feedback loop or extracts the ASE to the feedback loop. In addition, the amplifier is also provided with a filter 210 for filtering the specific wavelength of the seed beam or ASE. |
