OPTICAL TRANSMISSION SYSTEM

摘要

PURPOSE:To form the system with high quality by forming a trunk line system port of an optical branching device with a low loss asymmetrical optical branching device and forming a branch line system port of the optical branching device with a high loss asymmetrical optical branching device to set the share of the loss in response to the light receiving level of the branch system. CONSTITUTION:In the optical transmission system having optical tree structure where optical branching devices are arranged at an optional position of an optical transmission line 61, the optical branching devices are made up of asymmetrical optical branching devices 8-1 to 8-n-1 of a low loss for the trunk line system port and a high loss for the branch system port, and the share of the loss of the optical branching devices is set in response to a light receiving level of the branch system. Then an optical analog video signal sent from the optical transmitter 5 is sent through a trunk line system optical transmitter 61 and branched to a branch system transmission line 62 by the asymmetrical optical branching devices 8-1 to 8-n-1 arranged at an optional location in the trunk line system transmission line 61 and received by optical receivers 7-1 to 7-n. In this case, the low loss asymmetrical optical branching devices 8-1 to 8-n-1 are branched for the trunk line system optical transmitter 61 and the high loss asymmetrical optical branching devices 8-1 to 8-n-1 are branched for the branch line system optical transmitter 62.