Patent ID: 7307782

Claim:
A Raman amplifier provided at a predetermined position of an optical fiber transmission line and having an input end for entering signal light which propagates through said optical fiber transmission line and an output end for outputting said Raman-amplified signal light, comprising: an optical amplification section provided between said input end and said output end, and including a Raman amplification optical fiber for Raman-amplifying signal light which enters through said input end by supplying pumping light into said Raman amplification optical fiber; wherein said Raman amplifier further comprises a dispersion compensating section provided between said input end and said output end while being optically connected to said Raman amplification optical fiber, said dispersion compensation section compensating for a total chromatic dispersion of said optical fiber transmission line positioned outside of said Raman amplifier and said Raman amplification optical fiber positioned inside of said Raman amplifier, in a signal light wavelength band, wherein said Raman amplification optical fiber has an effective area of 30 μm 2 or less in the pumping light wavelength, and wherein a signal light propagation path from said input end to said output end, excluding said dispersion compensating section, has a total chromatic dispersion whose absolute value is 5 ps/nm or less in the signal light wavelength band.