| 摘要 |
<P>PROBLEM TO BE SOLVED: To improve a noise characteristic in a light amplifier 11 in a multilevel structure which is constituted of first and second rare earth element doped fibers 21 and 22 and a Raman amplification fiber 31. <P>SOLUTION: First EDF 21, the Raman amplification fiber 31 and the second EDF 22 are connected in series from a signal input side in this order. Excitation light from a first exciting light source 51 is made incident on the first EDF 21 and excitation light from a second exciting light source 52 is made incident on the Raman amplification fiber 31 and second EDF 22. A noise factor in first EDF 32 is made smaller than that of second EDF 22. <P>COPYRIGHT: (C)2003,JPO |
