| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain an optical transmission line capable of reducing the deterioration of optical signal strength-to-noise ratio (OSNR) of signal light, which is output by a Raman amplification from an optical fiber transmission line. <P>SOLUTION: The optical fiber transmission line is formed by using a plurality of optical fibers, excited light output from an exciting light source for Raman amplification is input to the optical fiber transmission line, the signal light propagating in the optical fiber transmission line is amplified by Raman amplification with a backward excitation in which the excited light is propagated in the reverse direction of the propagating direction of the signal light, the propagation loss of the signal light is compensated. The plurality of optical fibers composing the optical fiber transmission line are composed in the propagating direction of the signal light in the order: a first optical fiber which has first non-linear critical power which is the signal light power causing a non-linear deterioration; a second optical fiber which has second non-linear critical power which is smaller than the first non-linear critical power; and a third optical fiber which has third non-linear critical power which is smaller than the first non-linear critical power and larger than the second non-linear critical power, wherein the Raman amplification is performed within a range which does not exceed the respective first to third non-linear critical power. <P>COPYRIGHT: (C)2010,JPO&INPIT |
