| 摘要 |
PURPOSE:To make a bidirectional excitation method of a high performance possible at a low cost, by so controlling the outputs of first and second excitation lights based on the output of a monitoring part that the output or gain of an amplified light is kept constant, and by making the excitation lights highly reliable. CONSTITUTION:When the output of one of first or second excitation light is reduced, the controlling part of a means 6 for driving excitation light sources so controls the other excitation light that its output is increased. Thereby, since the outputs of third and fourth excitation lights are made constant, the excitation state of an amplifying optical fiber continues to be stable. Therefore, the output or gain of an amplified light is kept constant by virtue of the highly reliable excitation lights, and the long-term reliability of an optical fiber amplifier 1 can be improved. Also, since the third and fourth excitation lights branched by an optical mixing/branching device 4 have equal intensities to each other, even when the output of the first or second excitation light is varied, the states of the excitations applied to the amplifying optical fiber 1 from both its sides are balanced with each other. |
