| 摘要 |
PROBLEM TO BE SOLVED: To automatically continue normal operation even if a multi-mode fiber is connected to a single mode fiber in error. SOLUTION: An optical attenuator 4 attenuates the level of an optical signal received from an optical fiber 5, an optical switch 3 receives the optical signal from the fiber 5 and an optical signal attenuated by the attenuator 4 and selectively passes either one of these optical signals and a photoelectric converter 2 converts the optical signal passed through the switch 3 into an electric signal 6. A synchronization detector 8 judges the synchronization state of the electric signal 6 inputted from the converter 2 and controls the operation of the switch 3 so that the optical signal from the fiber 5 is passed when the signal 6 is a synchronizing state and the optical signal from the attenuator 4 is passed when the signal 6 is not the synchronizing state. |
