| 摘要 |
PURPOSE:To realize the economical and efficient optical communication system in which optical transmitters each employing a semiconductor laser having an optical output for back monitor to output an optical signal are connected in a loop. CONSTITUTION:A back monitor optical output of an LD 4a-1 is given to a standby line 7, a usual optical output is given to a utility line 6 via a spectroscope 4a-2, which extracts part of the usual optical output and it is monitored by an LD monitor circuit 4a-3. |
