| 摘要 |
PURPOSE:To devise the system to be avoided of any modification for existing nodes or the like when extension of a node is required by adopting the configuration such that a signal transfer coefficient is selected to be zero between an input terminal and an output terminal in pairs to be connected to a same node. CONSTITUTION:Three directional couplers 2, 3, 4 are interconnected in a triangle shape to constitute one star coupler 1. The directional coupler 2 is formed by melting clad layers of two optical fibers to make the core layers of each optical fiber close to each other. Thus, the star coupler in which the diagonal components of a transfer characteristic matrix are all zero is formed. A combined number of nodes connected to the star couplers is increased/decreased by increasing/decreasing number of the star couplers. Thus, the expansion/ reduction of the optical communication network is facilitated. |
