| 摘要 |
PURPOSE:To produce an optical branching filter in a short period of time by means of an easy general-purpose technique and general-purpose device by stretching a part of the outer circumferential surface of an optical fiber softened by heating. CONSTITUTION:The optical fiber 5 is partly heated by a heater 6 and is worked to a U shape. The end face of the optical fiber 7 which is the same in quality and diameter as the optical fiber 5 is pressed near to the peak of the U-shaped part of the optical fiber 5 and these fibers 5, 7 are welded by heating with a burner 8. While the part near the U-shaped part of the fiber 5 is heated, the fiber 7 is gradually pulled to stretch a part of the outer circumferential surface of the fiber 5 softened by the heating, then the fibers are cooled. The parts 9, 10 which are made into nearly the same outside diameter are cut and the cut pieces are removed. The core part 7a of the fiber 7 and the core part 5a are aligned and reconnected. A piece of the core within a piece of the optical fiber is thereby stretched to form the branch part and, therefore, the excellent branching filter is obtd.
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