Optical repeater using raman amplification, wavelength division multiplexed light transmission system, excitation light supply method and excitation light control method for raman amplification

An excitation light supply method for supplying excitation light to a Raman amplification medium of each one of a plurality of transmission systems transmitting wavelength division multiplexed signal lights, when Raman amplifying each wavelength division multiplexed signal light transmitted through each of said transmission systems, comprising:

• generating a plurality of excitation lights of different wavelengths corresponding to the wavelength bands of said wavelength division multiplexed signal lights;
• multiplexing said generated plurality of excitation lights, and then demultiplexing the multiplexed excitation light to a number corresponding to said plurality of transmission systems;
• and
• supplying each of said demultiplexed excitation lights to the Raman amplification medium of each of said transmission systems.

An excitation light supply method for supplying excitation light to a Raman amplification medium of each one of a plurality of transmission systems transmitting wavelength division multiplexed signal lights, when Raman amplifying each wavelength division multiplexed signal light transmitted through each of said transmission systems, comprising:

• generating a plurality of excitation lights of different wavelengths corresponding to the wavelength bands of said wavelength division multiplexed signal lights;
• multiplexing said generated plurality of excitation lights, and then demultiplexing the multiplexed excitation light to a number corresponding to said plurality of transmission systems;
• supplying each of said demultiplexed excitation lights to the Raman amplification medium of each of said transmission systems;
• detecting the power of wavelength division multiplexed signal light amplified by the Raman amplification medium of each of said transmission systems;
• and
• controlling the power of each of said generated excitation lights based on said detected wavelength division multiplexed signal light power of each of said transmission systems.