| 摘要 |
PURPOSE:To facilitate detection of noise light by providing a means to branch noise light emitted to the input side. CONSTITUTION:An optical amplifier 1 directly amplifies and emits light signal incident via an optical branch. At this time, the optical amplifier 1 generates noise light along with amplification of light signal, and noise light is emitted to the input side and the output side. The optical branch 2 consists of a photocoupler or an optical filter which transmits incident light signal, emits it to the optical amplifier 1, and reflects noise light emitted from the optical amplifier to emit it outside. Therefore, the optical branch 2 branches only noise light incident from the optical amplifier 1, so that noise light can be detected easily. In this case, the optical branch 2 can detect only noise light emitted to the input side, but can easily estimate the amount of noise light on the output side from the amount of noise light on the output side by previously detecting the correlation between the input side noise light and the noise light emitted to the emission side. |
