A fiber amplifier having a flat high gain and a low noise figure is known as a flattened high gain and low noise figure.

摘要

The present invention relates to an optical fiber amplifier having a high gain and a low noise figure which are flat with respect to changes in the intensity of an incident light signal and a pump power and includes a first isolator for blocking reverse propagation of incident signal light; A pump LD for applying pumping light; A first WDM for wavelength-splitting the wavelength of the signal light and the pumping light; Amplifying an incident light signal by the pumping light of the pump LD, and having a negative gain slope; A second WDM for wavelength-splitting the amplified signal light into a pump light and a signal light; A filter that attenuates signal light among output signals of the second WDM and has a negative signal attenuation slope; A third WDM for wavelength-splitting the signal light passing through the filter and the pumping light passing through the second WDM; Amplifying the incident light signal with the pump light, having a positive gain slope, the second EDF being of a different kind of material than the first EDF; And a second isolator for blocking reverse propagation of the signal that has passed through the second EDF.;According to the present invention, it has a high gain with respect to intensity of an incident light signal and a change in pump power, is flat, has a gain characteristic and a low noise figure.