| 摘要 |
<p>It has been desired to suppress the optical surge which occurs when a signal light accompanied by an abrupt light intensity change is inputted to an optical amplifier such as an EDF. The optical surge suppressing circuit comprises signal light branching means for branching the inputted first signal light into a second signal light and a third signal light and outputting them, a variable optical attenuator for attenuating and outputting the second signal light outputted by the signal light branching means, a photoelectric transducer for converting the third signal light outputted by the signal light branching means to an electric signal and outputting it, high-frequency component detecting means for detecting a high-frequency component contained in an electric signal outputted by the photoelectric transducer, and variable optical attenuator control means for controlling the attenuation of the signal light by the variable optical attenuator according to the detection result of the high-frequency component detecting means.</p> |
