FORWARD RAMAN AMPLIFIER, BIDIRECTIONAL RAMAN AMPLIFICATION SYSTEM, AND FORWARD RAMAN AMPLIFICATION SYSTEM

1 . A forward Raman amplifier comprising:

a plurality of pumping light sources with different wavelengths,

wherein the forward Raman amplifier, according to a fiber type or a zero-dispersion wavelength of the fiber, changes the number of pumping light sources to be emitted, changes a power ratio between the plurality of pumping light sources with the different wavelengths, or changes wavelength characteristics of a gain, according to a fiber type.

2 . The forward Raman amplifier according to claim 1 , wherein in a case where signal light exists within a wavelength band obtained by folding a pumping light wavelength with respect to a zero-dispersion wavelength on a wavelength axis, power of a pumping light source with the wavelength is turned off.

3 . The forward Raman amplifier according to claim 1 , wherein a pumping light source is mounted that has a wavelength that does not fall within a wavelength band obtained by folding a wavelength of signal light with respect to a zero-dispersion wavelength of a fiber on a wavelength axis.

4 . A forward Raman amplifier,

wherein in a case where signal light exists within a wavelength band obtained by folding a pumping light wavelength with respect to a zero-dispersion wavelength on a wavelength axis, a pumping light power ratio of the wavelength is lowered to be lower than a pumping light power ratio of a wavelength in which signal light does not exist within the wavelength band obtained by folding the pumping light wavelength with respect to the zero-dispersion wavelength.

5 . The forward Raman amplifier according to claim 4 , wherein in a case where signal light exists within a wavelength band obtained by folding a pumping light wavelength with respect to a zero-dispersion wavelength on a wavelength axis, power of a pumping light source with the wavelength is turned off.

6 . The forward Raman amplifier according to claim 4 , wherein a pumping light source is mounted that has a wavelength that does not fall within a wavelength band obtained by folding a wavelength of signal light with respect to a zero-dispersion wavelength of a fiber on a wavelength axis.

7 . The forward Raman amplifier according to claim 4 , wherein in addition, in a case where a plurality of the pumping light sources exists in which the signal light exists within the wavelength band obtained by folding the pumping light wavelength with respect to the zero-dispersion wavelength on the wavelength axis, a pumping light source closest to the zero-dispersion wavelength is quenched.

8 . The forward Raman amplifier according to claim 4 , wherein in addition, incoherent pumping light and coherent light are used as the pumping light, and

in addition, in a case where the signal light exists within the wavelength band obtained by folding the pumping light wavelength with respect to the zero-dispersion wavelength on the wavelength axis, for both of a coherent pumping light source and incoherent pumping light source, the coherent pumping light source is quenched, and a pumping light source closest to the zero-dispersion wavelength among the incoherent pumping light source is quenched.

9 . A bidirectional Raman amplification system comprising:

a forward Raman amplifier including a plurality of pumping light sources with different wavelengths and configured to, according to a fiber type or a zero-dispersion wavelength of the fiber, change the number of pumping light sources to be emitted, change a power ratio between the plurality of pumping light sources with the different wavelengths, or change wavelength characteristics of a gain, according to a fiber type; and

a backward Raman amplifier configured to generate wavelength characteristics of a gain in an opposite direction so as to compensate wavelength characteristics of a gain generated by the forward Raman amplifier.