| 摘要 |
PURPOSE:To secure continuance of the repeating action for the transmission line signals through formation of the optical by-pass circuit even when the optical transmitter has some trouble by installing the optical branch part, the optical cut-off part and the optical coupling part each between the transmission lines of the input and output sides. CONSTITUTION:Optical branching unit 12 is provided between the transmission lines of the input and output sides, and input optical signal Si is divided into two parts through branching half-mirror 12b. Thus reflected light Sr of one side is led into optical receiver 14; while transmitted light Sp of the other side is led into shutter 16b of optical breaker 16 each. Light Sr goes up to receiver 14 and then converted into the electric signal to be supplied to the reception circuit, and at the same time converted into the optical signal again at optical transmitter 22 via signal switch gate 21 to be delivered via optical coupler 18. On the other hand, light Sp actuates shutter driving circuit 16c by the optical by-pass command to open shutter 16d to be delivered through coupler 18. Accordingly, the repeating action can be continued for the transmission line signal even when transmitter 1 has some trouble. |
