Patent ID: 7130109

Claim:
An optical signal amplification device for outputting an output signal light which has a first wavelength that is the same as a wavelength of an input signal light and an intensity variation that is identical in phase with an intensity variation of the input signal light, said optical signal amplification device comprising: a first optical amplifying element having a mutual gain modulation function of outputting an output light including (i) the output signal light and (ii) a neighboring light which has a neighboring wavelength that is different from the wavelength of the output signal light and an intensity variation that is inverted in phase with respect to the intensity variation of the output signal light; signal-light inputting means inputting only the input signal light to said first optical amplifying element; a wavelength-selecting element extracting the output signal light of the first wavelength and at least a part of the neighboring light of the wavelength different from the first wavelength, from the output light outputted from said first optical amplifying element, such that the output signal light and said at least a part of the neighboring light are separated from each other; and optical feedback means for feeding back said at least a part of the neighboring light extracted by said wavelength-selecting element, to said first optical amplifying element, so that said at least a part of the neighboring light is inputted to said first optical amplifying element, for rendering said first optical amplifying element to generate a negative feedback amplification effect.