| 摘要 |
PROBLEM TO BE SOLVED: To provide the optical fiber coupler which demultiplexes and multiplexes light with directivity and its manufacture. SOLUTION: An optical fiber part 28 for a branch line is joined to an optical fiber part 21 for a trunk line with a large-diameter area 24 and the core 28a of the optical fiber part 28 for the branch line is joined directly to the core 24a of the large-diameter area 24, so the light from the optical fiber part 21 for the branch line is guided to the optical fiber part 21 for the trunk line through the large-diameter area 24. Light from a couple of thin-diameter areas 22 of the optical fiber part 21 for the trunk line, on the other hand, is not made incident on the entire area of the core/clad border surface of the large- diameter area 24 because of a decrease in the travel angle in a tapered area 25, so a light leak to the plastic optical fiber part 28 for the branch line can be suppressed. |
