Patent ID: 8351112
Filing Date: 2013-01-08
Classification: H01S,H04B

Abstract:
1. An optical amplifier comprising: a light source configured to generate excitation light; a first amplification medium configured to receive light obtained by combining wavelength-multiplexed signal light input into an input port and the excitation light; a second amplification medium disposed on a signal path between the first amplification medium and an output port of the optical amplifier; a loss medium that is optically coupled between the first amplification medium and the second amplification medium and is configured to receive the wavelength-multiplexed signal light separated from light output from the first amplification medium; a variable optical attenuator that is optically coupled between the first amplification medium and the second amplification medium, is disposed on an alternative path that bypasses the loss medium, and is configured to receive the excitation light separated from the light output from the first amplification medium; a first photodetector configured to detect power of light separated from the wavelength-multiplexed signal light transmitted from the second amplification medium to the output port; and a controller configured to set an amount of attenuation for the variable optical attenuator in accordance with a wavelength number of the wavelength-multiplexed signal light input into the input port, and control the amount of attenuation for the variable optical attenuator or output power of the light source on a basis of a result of detection performed by the first photodetector so that signal light power per wavelength of the wavelength-multiplexed signal light to be output from the output port becomes closer to a target value set in advance.