Patent ID: 7940453

Claim:
A method of operating a fiber amplifier characterized by a spectral gain curve, the method comprising: providing an input signal at a signal wavelength, wherein the signal wavelength lies within an in-band portion of the spectral gain curve extending from a first in-band wavelength to a second in-band wavelength, the in-band portion being characterized by a first amplitude range; providing pump radiation at a pump wavelength, wherein the pump wavelength is less than the signal wavelength and the pump radiation is characterized by a pump power; coupling the pump radiation to the fiber amplifier; absorbing a portion of the pump radiation in the fiber amplifier, wherein a power of the pump radiation exiting an output end of the fiber amplifier is greater than or equal to a power of the portion of the pump radiation absorbed in the fiber amplifier; and amplifying the input signal to generate an output signal, wherein all portions of the spectral gain curve at wavelengths less than the first in-band wavelength and greater than the pump wavelength are characterized by a second amplitude less than or equal to 10 dB greater than the first amplitude range.