Patent ID: 7982945

Claim:
An optical amplification module, comprising: a first optical amplification unit which amplifies an incident light to be amplified and emits a first amplified light, said first optical amplification unit comprising: a first optical amplification medium having an optical waveguide region which is doped with a rare earth element, and having a light entrance end on which the light to be amplified is incident and a light exit end which emits a first amplified light that has been amplified inside said first optical amplification medium; a first pumping light source for outputting a first pumping light of a predetermined wavelength; and a first optical multiplexer for multiplexing the light to be amplified and the first pumping light, said multiplexer being disposed on the light entrance end side of said first optical amplification medium such that the first pumping light propagates from the light entrance end to the light exit end of said first amplification medium; and a second optical amplification unit which further amplifies the first amplified light emitted from said first optical amplification unit and emits a second amplified light, said second optical amplification unit comprising: a second optical amplification medium having an optical waveguide region which is doped with a rare earth element in a higher concentration than the rare earth concentration of said first optical amplification medium, and having a light entrance end on which the first amplified light is incident and a light exit end which emits a second amplified light that has been amplified inside said second optical amplification medium; a second pumping light source for outputting a second pumping light of different wavelength from the first pumping light; and a second optical multiplexer for multiplexing the first amplified light outputted from said first optical amplification medium and the first pumping light together with the second pumping light, said optical multiplexer being disposed between said first optical amplification medium and said second optical amplification medium, wherein: unsaturated absorption of said first optical amplification medium is not less than 60% of unsaturated absorption of said second optical amplification medium, and population inversion in said second optical amplification medium is not greater than 40%.