| 摘要 |
PURPOSE:To reduce laser outputs from both transmitting/receiving units to low power even when only the optical fibers of one of the units are disconnected. CONSTITUTION:Each of the 1st and 2nd transmitting/receiving units 1, 2 is provided with the 1st and 2nd pilot signal generating parts 9, 11. When none of the 1st and 2nd pilot signals P1, P2 can be detected from the opposite unit 2 or 1, the unit 1 or 2 outputs the 2nd pilot signal P2 and a low power optical, output, and when the 2nd pilot signal P2 is received from the opposite unit 2 or 1, outputs the 1st pilot signal P1 and a low power optical output. When the 1st pilot signal P1 is received from the opposite unit 2 or 1, the unit 1 or 2 outputs the 1st pilot signal P1 and a high power optical output. |
