| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical branching and coupling unit which can prevent light generated owing to difference in numerical aperture from leaking as to optical branching and coupling unit consisting of optical fibers differing in numerical aperture. SOLUTION: A low numerical-aperture optical fiber 10 is provided with optical transmission parts 15 and 15, an optical branching and coupling part 13 which have a smaller diameter than those optical transmission parts 15 and 15, and tapered parts 14 and 14 which are continuous between the branching and coupling part 13 and optical transmission parts 15 and 15 and have the outer peripheral surfaces gradually decreased in diameter toward the branching and coupling part 13, and a high-numerical-aperture optical fiber 20 is connected to the branching and coupling part 13 by fusion splicing. |
