| 摘要 |
PURPOSE:To change easily a branch ratio by making circumferential walls of plural cores adjacent to one another and applying a synthetic resin hardened by light between these adjacent circumferential walls and irradiating the light to this synthetic resin extending over a preliminarily determined length to harden it. CONSTITUTION:Cores 1 and 2 are provided adjacently to each other for the purpose of connecting the light from the upstream side of the core 1 to them and branching and leading a part of this light to the core 2, and the synthetic resin hardened by light is applied between their circumferential walls. This synthetic resin is applied along axial lines of the core 1 and an end part 2a of the core 2 in a range having a length indicated by a line l2. The part having a length l1 corresponding to the branch ratio is exposed, and the left part (=l2-l1) is covered with a mask 4. The light is irradiated in this state to harden the synthetic resin in the part having the length l1, and the part having the length (l2-l1) which is not irradiated with the light has the synthetic resin washed away. It is desirable that the refractive index in the hardened part of the synthetic resin 3 hardened by light is made approximately equal to that of cores. Thus, the branch ratio of a branching circuit is changed easily. |
