| 摘要 |
PURPOSE:To perform controlling and monitor for light exchanger, by picking up the control signal with excellent S/N, through the branch and photo electric conversion for a part of light from communication optical fiber and passing via the narrow band filter. CONSTITUTION:Communication signal and the control signal having the band width sufficiently narrower that of the communication signal are transmitted in one optical fiber 1, and a part of the optical fiber 1 is provided with one or more control signal pick up circuits. The pick up circuit consists of the branch circuit 2 branching only a part of light of the fiber 1, photo detector 3 photo-electric-converting the output, and it picks up the control signal with good S/N, enabling to control and monitor the light exchanger. |
