Patent ID: 9077286
Filing Date: 2015-07-07
Classification: H01S,H03F,H04B

Abstract:
1. An optical amplifier comprising: an optical amplifier circuit that implements optical amplification on an optical signal input from an input end of the optical amplifier to output the amplified optical signal from an output end of the optical amplifier to a device through a transmission line; a branching circuit that branches light input from the output end toward the optical amplifier; a photo-detector that receives the light branched by the branching circuit, and to detect optical level of the received light; and a control circuit that reduces an amount of optical amplification of the optical amplifier circuit in case where the optical level detected by the photo-detector becomes more than or equal to a threshold previously fixed, wherein the control circuit increases the amount of optical amplification of the optical amplifier circuit when a variation in reduction of the optical level detected by the photo-detector becomes less than or equal to a predetermined variation, the variation of the optical level being brought by the reduction of the amount of optical amplification.