| 摘要 |
PROBLEM TO BE SOLVED: To avoid an adverse effect upon the eyes of human being even when an optical fiber is disconnected from an optical transmitter/receiver and to easily discriminate re-mounting. SOLUTION: When an optical fiber is disconnected and no signal arrives from the opposite transmitter/receiver any more, this is discriminated by a regular signal detector 14 and a dummy signal detector 15. As a result, a switch 8 is changed over, a second reference voltage is sent to an automatic optical output control mechanism 7 and the power of a semiconductor laser is reduced. At the same time, a switch 3 supplies a dummy optical signal to a semiconductor laser 5 in place of a regular signal and the dummy optical signal is outputted. At such a time point, the opposite transmitter/receiver outputs a dummy optical signal as well. When the optical fiber is mounted again, the dummy signal is detected and the output of the semiconductor laser 5 becomes a regular great value so that the regular signal can be outputted again. |
