Patent ID: 7880960
Filing Date: 2011-02-01
Classification: H01S,H04B

Abstract:
1. An optical amplifier for amplifying wavelength-division multiplexed light, comprising a first optical amplification unit which amplifies input light, a variable optical attenuation unit which attenuates an output of said first optical amplification unit, a second optical amplification unit which amplifies an output of said variable optical attenuation unit, and a loss amount control unit which controls an amount of loss to be introduced by said variable optical attenuation unit, wherein an external attenuating optical medium is inserted between said variable optical attenuation unit and said second optical amplification unit, and said loss amount control unit compensates for variations in optical loss of said external attenuating optical medium by controlling the amount of loss to be introduced by said variable optical attenuation unit, said optical amplifier further comprising: an abnormality detecting unit which detects abnormality in optical loss between said first and second optical amplification units based on a light level detected between said external attenuating optical medium and said second optical amplification unit; and a detection invalidating unit which invalidates any abnormality detected by said abnormality detecting unit when a light level detected between said variable optical attenuation unit and said external attenuating optical medium is lower than a predetermined threshold level.