Raman amplifier, raman amplifier control method, and optical communication system

A control method for a Raman amplifier comprising, at least, a Raman amplification optical fiber for Raman-amplifying a plurality of signal channels of signal light having respective center optical frequencies different from each other, and a pumping light supply section, said control method comprising the steps of:

• supplying N (N being an integer of 2 or more) channels of pumping light having respective center optical frequencies different from each other to said Raman amplification optical fiber;
• detecting a part of said signal light Raman-amplified within said Raman amplification optical fiber when said pumping light is supplied thereto;
• and
• dividing said detected Raman-amplified signal light into N optical frequency ranges defined so as to include respective Raman amplification peaks as optical frequencies lower than respective center optical frequencies of said pumping channels of pumping light by an optical frequency shift of 13.5 to 15.7 THz, and controlling said pumping light supply section such that said Raman-amplified signal light has a power fluctuation of 2 dB or less in each of thus divided N optical frequency ranges.

A Raman amplifier comprising:

• an optical fiber for Raman-amplifying a plurality of signal channels of signal light having respective center optical frequencies different from each other;
• a pumping light supply section for supplying N (N being an integer of 2 or more) pumping channels of pumping light having respective center optical frequencies different from each other to said optical fiber;
• and
• a feedback section for detecting a part of said signal light Raman-amplified within said optical fiber when said pumping light is supplied thereto, and controlling said pumping light supply section such that said Raman-amplified signal light has a substantially flat power spectrum with respect to an optical frequency direction according to a result of said detection;
• said feedback section dividing said detected Raman-amplified signal light into optical frequency ranges having a number identical to that of said pumping channels of said pumping light, and controlling said pumping light supply section such that said Raman-amplified signal light included in each of thus divided optical frequency ranges has a power average fluctuation of 2 dB or less,
• wherein said feedback section comprises:
• a photodetector for monitoring a power of said Raman-amplified signal light and a pumping light power at each of said center optical frequencies of said pumping channels;
• and
• a controller for determining, when dividing said Raman-amplified signal light into optical frequency ranges having a number identical to that of said pumping channels, an optical frequency indicating a boundary between said optical frequency ranges according to a result of detection effected by said photodetector.

A control method

• for a Raman amplifier comprising, at least, a Raman amplification optical fiber for Raman-amplifying a plurality of signal channels of signal light having respective center optical frequencies different from each other, and a pumping light supply section, said control method comprising the steps of:
• supplying N (N being an integer of 2 or more) channels of pumping light having respective center optical frequencies different from each other to said Raman amplification optical fiber:
• detecting a part of said signal light Raman-amplified within said Raman amplification optical fiber when said pumping light is supplied thereto;
• and
• dividing said detected Raman-amplified signal light into optical frequency ranges having a number identical to that of said pumping channels of said pumping light, and controlling said pumping light supply section such that said Raman-amplified signal light included in each of thus divided optical frequency ranges has a power average fluctuation of 2 dB or less,
• wherein, when dividing said Raman-amplified signal light into optical frequency ranges having a number identical to that of said pumping channels, an optical frequency indicating a boundary between said optical frequency ranges is determined according to a result of detection of a pumping light power at each of center optical frequencies of said optical frequency ranges.