Patent ID: 6867907

Claim:
A pumping light source unit for Raman amplification, said pumping light source unit comprising: a pumping light supply system including N (≧2) pumping light sources for outputting N channels of pumping light having respective wavelengths different from each other, at least one of said pumping light sources including a wavelength variable pumping light source adapted to change a channel wavelength of pumping light outputted therefrom; a multiplexer for multiplexing said N channels of pumping light respectively outputted from said N pumping light sources; and an output structure for outputting said pumping light multiplexed by said multiplexer, wherein said wavelength variable pumping light source includes an external resonator type wavelength variable laser unit comprising a pumping light laser, a resonance grating, and a channel wavelength adjusting system for changing a wavelength of light reflected by said resonance grating.