Patent ID: 8854727
Filing Date: 2014-10-07
Classification: H01S,H04B,H04J

Abstract:
1. An optical amplifier comprising: a first amplifier that excites an inputted signal light by a first excitation light to amplify the inputted signal light; a variable optical attenuator that attenuates the signal light outputted from the first amplifier; a second amplifier that excites the signal light outputted from the variable optical attenuator by a second excitation light to amplify the signal light; a mode selector that selects an operative state of the optical amplifier from a first mode and a second mode; a gain controller that, when the operative state is the first mode, controls the first excitation light and the second excitation light to be outputted to the first amplifier and the second amplifier, respectively so that a gain of the power of the signal light becomes constant; a first output controller that, when the operative state is the second mode, controls the first excitation light to be outputted to the first amplifier; a second output controller that, when the operative state is the second mode, controls the second excitation light to be outputted to the second amplifier so that a spontaneous emission light having a fixed level is outputted from the second amplifier to the outside of the optical amplifier; and an attenuation controller that controls an attenuation of the variable optical attenuator according to an input level of the signal light when the operative state is the first mode, and controls the attenuation so as to become a given value larger than a value in the first mode when the operative state is the second mode.