| 摘要 |
<p>An optical amplifier includes: an optical amplification unit implementing optical amplification on an optical signal input from an input end to output an amplified optical signal from an output end to a device through a transmission line; a branching unit branching light from the output end, where the light contains reflected-light or/and optical feedback; a photo-detector receiving the branched light and detecting the optical level of the received light; and a control circuit reducing an amount of optical amplification of the optical amplification unit in a case where the detected optical level becomes greater than or equal to a first threshold. The control circuit normalizes the amount of optical amplification in case where a variation of the optical level detected by the photo-detector becomes less than or equal to a second threshold, where the variation of the optical level has been caused by the reduction of the amount of optical amplification.</p> |
