Optical communication system with two parallel transmission paths

摘要

In an optical communication link a first node ( 30 ) with transmission means ( 50 ) and a second node with receiving means ( 40 ) are connected by at least two optical fiber transmission paths ( 100,200 ). One path serves as the working path, while the remaining path or paths serve as protection paths. The transmission means in the first node is connected to an optical signal power splitter ( 60 ) which couples the signal power from the transmitting means unequally into the different transmission paths. This uneven coupling of signal power imposes greater losses in one path than in the other or others. By arranging the splitter to couple a higher proportion of the transmitted optical power into the path that has the highest inherent losses the additional loss imposed on this path is reduced. Thus the maximum path loss between any two nodes can be minimized. This in turn means that the link length and also the size of the network is virtually unaffected by using the same transmitter.