| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical branching device which is inexpensive and is flat in amplification gain. SOLUTION: The signal light amplified by multiplexing with exciting light in a rare earth added optical fiber 15 for optical amplification is passed through rare earth added optical fibers 19-1 to 19-8 on an output side, by which the signal light of the specific wavelength increased in the amplification factor is optically absorbed and, therefore, the amplification gain deviation is made small. If an isolator 11 of a polarization independent type is inserted between the rare earth added optical fiber 15 for optical amplification and the optical branching device 17, light reflection is suppressed and loss is lowered. If Al2 O3 is added to the cores of the rare earth added optical fibers 15, 19-1 to 19-8, the amplification gain deviation is made smaller. |
