Patent ID: 9647789
Date: 2017-05-09
CPC Classifications: H04J

Claim:
1. An optical transmission system comprising: a first optical transmission device configured to include a splitter that has at least a first port, a second port, and a third port that outputs branched input light, branching ratios of the first port and the second port being variable, and a controller including a processor that reduces an optical level of output light from the first port of the splitter to be monitored so that an alarm for testing of an alarm function is detected at a fourth port coupled to the first port of the splitter via a transmission path and increases an optical level of output light from the second port according to the reduced optical level of output light from the first port of the splitter so as to maintain the optical level of output light from the third port by controlling the branching ratios; and a second optical transmission device coupled to the first optical transmission device via a transmission path, the second optical transmission device including a photo detector that monitors the optical level of output light from the first port and generates an alarm according to the optical level of output light from the first port, wherein the second optical transmission device further includes a switch that selects one of output light from the first port of the first optical transmission device and output light from another optical transmission device, the switch selecting the output light from the other optical transmission device when the photo detector issues the alarm.