Raman amplifier and optical communication system including the same

A Raman amplifier provided at a predetermined position on an optical fiber transmission line and has 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 which is installed between said input end and said output end, and includes a Raman amplification optical fiber for Raman-amplifying signal light which enters through said input end by the supply of pumping light into said Raman amplification optical fiber;
• a dispersion compensation section provided between said input end and said output end while being optically connected to said Raman amplification optical fiber, and compensates for a total chromatic dispersion in the signal light wavelength of said optical fiber transmission line positioned outside of said Raman amplifier and said Raman amplification optical fiber positioned inside of said Raman amplifier;
• and
• a pumping light source supply system, comprising a first pumping light source, and supplies said pumping light to said Raman amplification optical fiber, and a first optical multiplexing structure for guiding the pumping light from said first pumping light source to said Raman amplification optical fiber without passing through said dispersion compensating optical fiber, and
• wherein said Raman amplification optical fiber has an effective area of 30 μm2 or less in the pumping light wavelength, and a parameter gR of 2.3×10−14 m/W or more.